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  • 51.
    Ileri, Ömer
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS.
    Broker Coordination in Demand Responsive Dynamic Spectrum Access Settings2009In: 2009 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-8, 2009, p. 2781-2786Conference paper (Refereed)
    Abstract [en]

    In this paper we propose cooperative/noncooperative operation models for revenue seeking spectrum brokers who coordinate to manage access to the same spectrum bands in adjacent areas. We consider a setting where users of spectrum are involved in peer-to-peer links with QoS requirements. Each wireless transmission (link) is priced collectively by all revenue seeking brokers whose responsibility areas are affected by the transmission (via interference). We propose a two-level coordination mechanism. At the pricing-level, the brokers affected by a given link collectively determine prices. At the admission level, all brokers potentially affected by all transmissions collectively determine the set of link requests that are to be permitted. The links are modeled as price sensitive users who may or may not form connections, based on the total price asked. Experimental results show that cooperation significantly increases both the number of active links and broker revenues. Relative gains achieved by pricing level cooperation alone or admission level cooperation alone depend on price sensitivity parameters for the links as well as the total number of link formation requests.

  • 52. Janssen, G. J. M.
    et al.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Capacity assessment of a cellular radio system using a narrowband multiuser detector2003In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 2, no 4, p. 703-713Article in journal (Refereed)
    Abstract [en]

    With a narrowband multiuser detector (MUD), multiple users can simultaneously share the same channel without using a bandwidth-expanding signature code when sufficient power differences at the receiver are maintained. In this paper, we assess the capacity gain that can be achieved in a hypothetical cellular system with centralized power control, using a narrowband MUD based on successive cancellation. The power-control algorithm is adapted to multiple users per channel in a cell. Simulation results are presented for two heuristic carrier-to-interference ratio-based channel-assignment schemes. The MUD allows for a substantial capacity gain due to a tighter packing of users in a channel. The observed gain compared with a conventional single user-per-channel system, ranges from 1.4 to 5 for cluster sizes C = 1 and 7, respectively.

  • 53.
    Janssen, Gerard J. M.
    et al.
    Telecommunication and Traffic-Control Systems Group, Department of Information Technology and Systems, Delft University of Technology, 2600 GA Delft, The Netherlands.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Capacity of a Cellular Radio System Using a Narrowband Multiuser Detector2002Conference paper (Refereed)
    Abstract [en]

    With a narrowband multiuser detector (MUD), multiple users can simultaneously share the same chan- nel without using a bandwidth expanding signature code when suficient power differences at the receiver are main- tained. In this paper we assess the capacity gain that can be achieved in a hypothetical cellular system with centralized power control, using a narrowband MUD based on succes- sive cancellation. The power control algorithm is adapted to multiple users per channel in a cell. Simulation results are presented for two heuristic CIR based channel assign- ment schemes. The MUD allows for a substantial capacity gain due to a tighter packing of users in a channel. The observed gain compared to a conventional single user per channel system, ranges from 1.4 to 5 for cluster sizes C = 1 and 7, respectively.

  • 54.
    Janssen, Gerard J. M.
    et al.
    Telecommunication and Traffic-Control Systems Group, Department of Information Technology and Systems, Delft University of Technology, 2600 GA Delft, The Netherlands.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Power Control and Stepwise Removal Algorithms for a Narrowband Multiuser Detector in a Cellular System2002In: 2002 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-5, CONFERENCE PROCEEDINGS, New York: IEEE , 2002, p. 345-350Conference paper (Refereed)
    Abstract [en]

    With a narrowband multiuser detector (MUD), multiple users can simultaneously share the same channel without using a bandwidth expanding signature code when sufficient power differences at the receiver are maintained. In this paper, we estimate the capacity that can be achieved in a hypothetical cellular system with centralized power control, using a narrowband MUD based on successive cancellation. The power control algorithm is adapted to multiple users per channel in a cell.Capacity results from simulations based on user removal are presented for three removal algorithms. It is shown that the narrowband MUD has a significant potential for capacity gain due to a tighter packing of users in a channel.

  • 55.
    Johansson, Klas
    et al.
    KTH, Superseded Departments, Wireless at KTH.
    Furuskär, Anders
    Karlsson, Peter
    Zander, Jens
    KTH, Superseded Departments, Wireless at KTH.
    Relation between base station characteristics and cost structure in cellular systems2004In: 2004 IEEE 15TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-4, PROCEEDINGS, NEW YORK: IEEE , 2004, p. 2627-2631Conference paper (Refereed)
    Abstract [en]

    A simple method for estimating the costs of building and operating a cellular mobile network is proposed. Using empirical data from a third generation mobile system (WCDMA) it is shown that the cost is driven by different factors depending on the characteristics of the base stations deployed. When site density increase, operational and transmission costs tend to dominate rather than radio equipment and site costs. The results also show how, for different capacity requirements, the costs can be minimized by a proper selection of for example macro, micro and pico base stations. In many scenarios the macro base stations yield the lowest cost, indicating that coverage (cell range) is an important parameter when designing wireless systems.

  • 56.
    Johansson, Klas
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Furuskär, Anders
    Ericsson AB, SE-164 80 Stockholm, Sweden.
    Cost Efficient Deployment of Heterogeneous Wireless Access Networks2007In: 2007 IEEE 65th Vehicular Technology Conference, Vols 1-6, 2007, p. 3200-3204Conference paper (Refereed)
    Abstract [en]

    As data applications become more popular in mobile networks, usage patterns will be different from mobile telephony. Demand for higher bit rates is found in certain areas ("hot spots"), whereas the requirement for wide area coverage remains. Previous work has shown that using classical cellular hot-spot techniques (e.g., micro-cells) with a single radio access technology imply high-cost solutions. Instead, combining several, carefully chosen, access technologies in an efficient manner, leads to reduced infrastructure related costs while retaining a sufficient quality of service. In this paper, we estimate the user data rates achievable by complementing an urban macro cellular high speed packet access (HSPA) system with different hot spot solutions. When deployed at comparable cost levels, "dense macro", micro, and pico HSPA base stations yield a similar performance in downlink. Thanks to more spectrum bandwidth, IEEE 802.11a WLAN supports higher data rates in downlink both on average and for the lower percentiles of users. For the uplink, which in principal is noise limited already with a few hot spots deployed, indoor (pico and WLAN) base stations outperform outdoor systems, which are subject to severe propagation losses for indoor users.

  • 57.
    Johansson, Klas
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Furuskär, Anders
    Ericsson AB, SE-164 80 Stockholm, Sweden.
    Modelling the cost of heterogeneous wireless access networks2007In: International Journal of Mobile Network Design and Innovation, ISSN 1744-2869, Vol. 2, no 1, p. 58-66Article in journal (Refereed)
    Abstract [en]

    Heterogeneous wireless access networks are today considered to be a key enabler for affordable wireless access to the internet. Thanks to the diverse usage patterns and quality of service requirements for mobile and wireless data services, operators may reduce their costs significantly by exploiting different radio access technologies. These are then accessed via 'multiradio' terminals that automatically select between available systems. As a means to identify efficient combinations of radio access technologies, we propose a methodology to estimate the total infrastructure cost for non-uniform traffic distributions. With a few numerical examples including the packet data optimised evolutions of third generation mobile systems (3G) as well as Wireless Local Area Network (WLAN) technology, the model is used to quantify the average total cost of different system configurations. The methodology should prove useful as a basis for more specific analysis of the economics of heterogeneous wireless access networks.

  • 58.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Han, Sang-Wook
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Competitive Network Power Control between Operators in Shared SpectrumManuscript (preprint) (Other academic)
  • 59.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Li, Zhe
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Luo, Qiuchan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Fathali, Farnaz
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Vizcaino, Alexandre
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Impact of asymmetric transmission power on operator competition in shared spectrum2012In: Communication Technologies Workshop (Swe-CTW), 2012 Swedish, IEEE , 2012, p. 25-29Conference paper (Refereed)
    Abstract [en]

    To maintain affordable access for the rapidly increasing mobile traffic, base station deployment has to be tailored to hot-spot areas and primarily indoors where facility owners, e.g., shopping malls or hotels, mostly provide wireless service. Since such local access providers (LAPs) do not have access to exclusive spectrum, one proposed option is sharing spectrum with other nearby LAPs, e.g. unlicensed or secondary spectrum. Due to limited or no coordination between the LAPs, they selfishly access the spectrum, causing harmful interference to the neighboring networks. Especially by increasing transmission power, one operator may attempt to improve its own throughput at the expense of its neighbors. In this paper, we explore the impact of power asymmetry on competition between LAPs. We model the competition between two networks with different maximum power constraints as a network-wide power control game. By analyzing the pure Nash equilibria, we find that a lower power (LP) network becomes more aggressive to overcome the inter-network interference. Due to the aggressive behavior, sharing spectrum can out-perform fixed spectrum split even for the LP network, provided that the power asymmetry is below a certain limit. On the other hand, a higher power (HP) network is mainly affected by its own 'self-interference' so that it has little incentive to employ complicated inter-operator interference management schemes. In addition, we demonstrate that the power asymmetry limit strongly depends on the inter-network propagation conditions, e.g., inter-building distance or building penetration loss.

  • 60.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Jens, Zander
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    The Validity of Unlicensed Spectrum for Future Local Highcapacity Services2013Conference paper (Refereed)
    Abstract [en]

    Unlicensed spectrum indeed initiates high-data rate wireless services with the combination of the great success of Wi-Fi technology. Interestingly, the local high data rate services are deployed and invested by non-traditional local actors, e.g., facility owners who have local fixed line infrastructure. Motivated by the great success of the Wi-Fi eco-system, there are growing interests from various regulatory initiatives on short-range indoor shared spectrum access to continuously foster new business innovations and local investment by new players. Despite of flexible spectrum access and almost no regulatory management overhead, it is still not so clear that the traditional unlicensed approach can work for future high-capacity services where require extremely denser deployment than today. In this paper, we aim to discuss the validity of the traditional unlicensed approach for the new local operators in an economic aspect. We evaluate the required deployment cost of conventional Wi-Fi system and compare it with a hypothetical cellular-like system with marginal regulatory coordination. We found that the traditional node-level etiquettes in unlicensed band work as system design constraints, leading to too conservative full distributed systems. Although the current unlicensed band approach is the lowest cost solution for relatively low-capacity services, it may not be work at future high-capacity provisioning. Thus, regulations need to be designed to allow more coordinated systems such as cellular-like technologies with certain inter-network regulation.

  • 61.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Attainable User Throughput by Dense Wi-FiDeployment at 5 GHz2013In: 2013 IEEE 24th International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), IEEE conference proceedings, 2013, p. 3418-3422Conference paper (Refereed)
    Abstract [en]

    Most of currently deployed Wi-Fi networks use the IEEE 802.11b/g standard and operate in 2.4 GHz ISMband. As mobile traffic demand rapidly increases, significant Wi-Fi deployment in the still very lightly used 5 GHz band is anticipated. In combination with the recent PHY amendments, e.g., 802.11ac, such Wi-Fi in many settings emerges as a strong competitor to small cellular deployment. In this paper, we aim to quantify what total capacity and which data rates per user can be supported by high-density, the state-of-the-art 5 GHz Wi-Fi deployment. Unlike previous studies, we consider the effect of densification by explicitly modeling the different level of interference among access points for office-type scenarios with various internal wall losses. Although abundant spectrum availability at 5 GHz may compensate for system inefficiency caused by carrier sensing and contention, we find that there is a capacity limit. This capacity limit depends on propagation environments and is especially low in 'open' environments or environments with low wall losses. To operate at capacities above this limit, cellular systems with their more advanced interference mitigation techniques are required.

  • 62.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cooperation and Competition between Wireless Networks in Shared Spectrum2011In: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC), New York: IEEE , 2011, p. 284-288Conference paper (Refereed)
    Abstract [en]

    As the regulation in wireless communications is moving toward a more flexible and efficient way of managing radio spectrum, it is envisaged that multiple small-sized cellular networks owned by different operators will operate in close vicinity on shared spectrum. This brings a new interference environment where a cell is interfered by not only base stations in own network but also those in other networks. These networks may compete for their own utilities in a selfish manner or cooperate in order to minimize the mutual interference. Since a cooperation between the networks requires a business-wise agreement or extra infrastructure cost, the operators have to identify how much they will benefit from the cooperation. In this paper, we compare the effects of competition and cooperation between the cellular networks. The competition and cooperation are modeled as a transmit power control in downlink. It is observed that the cooperation in an average sense gives better network utility. However, as the network size increases, the cooperation gain diminishes significantly. Furthermore, the marginal separation of network deployments, e.g., indoor deployments in adjacent buildings, can notably shrink the cooperation incentive.

  • 63.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cost and Feasibility Analysis of Self-deployed Cellular Networks2011In: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC), New York: IEEE , 2011, p. 248-252Conference paper (Refereed)
    Abstract [en]

    A self-deployed network is considered to be one of cost-efficient deployment solutions by skipping an expensive network planning process. However, it may result in the serious degradation of capacity or the infeasibility of coverage constraint due to the rise of interference although radio adaptation techniques are employed. Therefore, deployment decision makers, e.g., operators, need to identify when and where the self-deployed network is feasible and economical compared with the planned network. For this, we estimate the average network throughput of the self-deployed network subject to a coverage constraint and compare it with the planned network. Three distinct regions of self-deployment are identified where different deployment strategies are required: infeasible, cost-effective, and uneconomical. We evaluate how the regions alter according to different channel environments and make suggestions for economical deployment.

  • 64.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cost saving of DynamicCoordination using Best-effortBackhaulManuscript (preprint) (Other academic)
  • 65.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Economic Hotspot Deployment Strategy: Denser Wi-Fior Coordinated Pico-cellular?Article in journal (Other academic)
    Abstract [en]

    Rapidly increasing traffic demand has forced indoor operators to deploy more and more Wi-Fi access points (APs). As AP density increases, inter-AP interference rises and may limit the capacity. Alternatively, cellular technologies using centralize dinterference coordination can provide the same capacity with the fewer number of APs at the price of more expensive equipment and installation cost. It is still not obvious at what demand level more sophisticated coordination pays off in terms of total system cost. To make this comparison, we assess the required AP density of three candidate systems for a given average demand: a Wi-Fi network, a conventional pico-cellular network with frequency planning, and an advanced system employing multi-cell joint processing. Numerical results show that dense Wi-Fi is the cheapest solution at a relatively low demand level. However, the AP density grows quickly at a critical demand level regardless of propagation conditions. Beyond this “Wi-Fi network limit”, the conventional pico-cellular network works and is cheaper than the joint processing in obstructed environments, e.g., furnished offices with walls. In line of sight condition such as stadiums, the joint processing becomes the most viable solution. The drawback is that extremely accurate channel state information at transmitters is needed.

  • 66.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Economic Spectrum Reuse between Inbuilding Wireless Access NetworksManuscript (preprint) (Other academic)
  • 67.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    High capacity indoor and hotspot wireless systems in shared spectrum: A techno-economic analysis2013In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 51, no 12, p. 102-109Article in journal (Refereed)
    Abstract [en]

    Predictions for wireless and mobile Internet access suggest an exponential traffic increase, particularly in in-building environments. Non-traditional actors such as facility owners have a growing interest in deploying and operating their own indoor networks to fulfill the capacity demand. Such local operators will need spectrum sharing with neighboring networks because they are not likely to have their own dedicated spectrum. Management of internetwork interference then becomes a key issue for high capacity provision. Tight operator-wise cooperation provides superior performance, but at the expense of high infrastructure cost and business-related impairments. Limited coordination, on the other hand, causes harmful interference between operators, which in turn will require even denser networks. In this article, we propose a techno-economic analysis framework for investigating and comparing indoor operator strategies. We refine a traditional network cost model by introducing new inter-operator cost factors. Then we present a numerical example to demonstrate how the proposed framework can help us to compare different operator strategies. Finally, we suggest areas for future research.

  • 68.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Is Multicell Interference Coordination Worthwhile in Indoor Wireless Broadband Systems?2012In: 2012 IEEE Global Communications Conference (GLOBECOM), IEEE , 2012, p. 4255-4260Conference paper (Refereed)
    Abstract [en]

    The rapid growth in demand for mobile and nomadic wireless access forces the use of more and more base stations (BSs). In such dense networks, various techniques for multicell interference coordination have been investigated. However, whether or not the interference coordination provides cost benefit compared with a loosely coordinated system is not obvious because the tight coordination at PHY-layer is likely to need an expensive high-speed backbone infrastructure. In this paper, we assess the worthiness of the tight interference coordination, referred to as coordination gain, in various indoor environments. We compare a hypothetical interference-free system as an upper bound with a simple interference-limited system opportunistically avoiding interference. The range of possible coordination gain is examined for various wall losses, path loss exponents, building shapes, and deployment density. Results show that substantial gain can be achieved in dense deployment at open areas with low path loss exponent, e.g., lightly furnished offices partitioned with soft walls. Nevertheless, the coordination gain significantly drops in the presence of marginal wall loss regardless of the other environmental factors.

  • 69.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Operator competition with asymmetric strategies in shared spectrum2012In: 2012 IEEE Wireless Communications and Networking Conference, WCNC, IEEE Communications Society, 2012, p. 3183-3187Conference paper (Refereed)
    Abstract [en]

    As the regulation in wireless communications is moving toward a more flexible and efficient way of managing radio spectrum, it is envisaged that multiple small-sized cellular networks owned by different operators, e.g., facility owners or local operators, will operate in close vicinity on shared spectrum. In this environment, the networks may compete for their own utilities in a selfish manner with giving harmful internetwork interference to competitors. In practice, it is not so unusual that each operator has different fairness criteria or quality of service (QoS) strategies by employing distinct objective functions from competitors. Particularly, we in this paper study power control competition between two networks with the sum of rates (SR) and the minimum rate (MR) as their objective functions, respectively. By exploring Nash equilibria, we identify that the MR network benefits from the objective asymmetry thanks to the adaptability of its competitor, i.e., no constraint in the SR objective. On the other hand, the SR network takes disadvantage due to the fairness requirement reflected in the MR objective of its competitor. However, such asymmetry effects in competition becomes negligible with marginal network separation, e.g., indoor deployment in adjacent buildings. Additionally, we identify cooperation potential with the proper choice of a common objective function although the asymmetric objectives are difficult to be aligned.

  • 70.
    Karlsson, Robert S.
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Hierarchical Cell Structure for FRAMES Wideband Wireless Access1996In: Conf. Proc. ACTS Mobile Telecommunications Summit 96, 1996, p. 785-791Conference paper (Refereed)
    Abstract [en]

    To provide sufficient capacity in traffic hot spots, small micro cells are needed to complement macro cells providing low cost large area coverage. These problems can be solved by using a mixed cell structure with macro cells for coverage and micro cells for capacity. Such a scenario, where coverage is provided from both macro and micro cells in a large part of the service area, is often referred to as an HCS (Hierarchical Cell Structure). One common way to provide radio resource management in an HCS scenario is to divide the available spectrum between the two cell layers into one macro cell band and one micro cell band. The key problem in these scenarios is that due to the large dynamic range of received signals, the suppression of inter-band interference may not be sufficient to provide adequate Signal-to-interference ratios at all times. The unwanted radiation of high power macro cell terminals into the micro cell band may cause severe difficulties to the micro cell base station receivers, tuned to the low power micro cell terminals. In the paper, three candidate multi-access schemes proposed in the ACTS FRAMES project were studied using a simple macro/micro cell scenario in order to assess the width of these problems. Results indicate that there are no major performance differences between the different schemes for the up-link scenario. The down-link scenario was shown to yield much worse results than the up-link scenario and only the CATS2 and the narrowband SMA1 schemes were achieving acceptable performance at a very low noise floor.

  • 71.
    Karlsson, Robert S.
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Hierarchical Cell Structures for Future Wideband Wireless Access1997Conference paper (Refereed)
    Abstract [en]

    To provide sufficient capacity in traffic hot spots, small micro cells are needed to complement macro cells providing low cost large area coverage. These problems can be solved by using a mixed cell structure with macro cells for coverage and micro cells for capacity. Such a scenario, where coverage is provided from both macro and micro cells in a large part of the service area, is often referred to as an HCS (Hierarchical Cell Structure). One common way to provide radio resource management in an HCS scenario is to divide the available spectrum between the two cell layers into one macro cell band and one micro cell band. The key problem in these scenarios is that due to the large dynamic range of received signals, the suppression of inter-band interference may not be sufficient to provide adequate Signal-to-interference ratios at all times. The unwanted radiation of high power macro cell terminals into the micro cell band may cause severe difficulties to the micro cell base station receivers, tuned to the low power micro cell terminals. In the paper, three candidate multi-access schemes proposed for the third generation systems in the ACTS FRAMES project were studied using a simple macro/micro cell scenario in order to assess the width of these problems. Results indicate that there are no major performance differences between the different schemes for the up-link scenario. The down-link scenario was shown to yield much worse results than the up-link scenario and only the CATS2 and the narrow band SMA1 schemes were achieving acceptable performance at a very low noise floor. The power control scheme is very important for the performance. When using SIR balanced power control the outage caused by external interference is gradually increasing as the interference increases. If constant received power control is used the system will work as long as the external interference is below a certain level and when interference increases above this level the outage will increase rapidly.

  • 72.
    Khamit, Saltanat M.
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Competitive Spectrum Allocation in Heterogeneous Coverage Areas2011In: 17th European Wireless Conference 2011, EW 2011, VDE Verlag GmbH, 2011, p. 313-318Conference paper (Refereed)
    Abstract [en]

    It could be costly to deploy a full coverage mobile broadband service with high bandwidth for a single operator. The development of low cost radio network equipment for short range coverage could trigger off a new scenario. Some providers may invest heavily to provide coverage in a wide area, while other providers would invest considerably less to provide coverage in a "hotspot" (small area). There exist two business models; in the first, the providers share their networks explicitly in a cooperative manner. In the second model, the providers compete with each other for users. This paper studies the competitive case, where providers have heterogeneous (partially overlapping) coverage. We analyse which service provisioning conditions are viable to the hotspot provider. The obtained results highlight the importance of infrastructure investments that characterized by degree of competition in the market. The system performance is also affected by the choice of sensitivity towards price and QoS. The results indicate that the hotspot provider could have a profit under given spectrum access mechanism and competition setting, which both would affect the level of the its profitability.

  • 73.
    Khamit, Saltanat
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Towards Open Mobile Broadband Market with Energy-Efficient Deployment2011In: Proceedings of the 10th Scandinavian Workshop on Wireless Ad-hoc Networks (ADHOC'11): Wireless Architectures for the Internet Things, 2011Conference paper (Other academic)
    Abstract [en]

    A growing demand for mobile broadband services will, sooner or later, cause a service provider to face problems in terms of network capacity. The pressurizing situation is more noticeable in a highly competitive environment. It is challenging for a new service provider to maximize the profitability while, at the same time, maintain high quality services. For virtually any network deployment strategy, the service provider will need to look at ways to reduce capital expenses (CAPEX) to decrease the cost per service. A better energy utilization is believed to have the potential to lower the network operation expenses (OPEX) and to balance network coverage versus user traffic. A cost structure and energy-efficiency in the mobile broadband network is crucial for success. In this paper, we consider a competition between incumbent and entrant providers, where the entrant chooses a suitable deployment strategy at the market entry. Both providers are profit- maximizers. We propose two competitive deployment strategies (“Cost Leadership” and “Differential Pricing” strategy) with an energy consumption constraint. The system performance is evaluated in terms of network size (market share), transmitted power, antenna height and user preference. The simplistic model used in this paper gives a clear understanding of investment needed for the expected coverage and capacity of the network. A provider who chooses to deploy a radio access technology smartly, focusing primarily on business strategy and cost efficiency, would benefit greatly.

  • 74.
    Kim, Seong-Lyun
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Rosberg, Zvi
    IBM, Haifa Research Laboratory.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Combined power control and transmission rate selection in cellular networks1999In: Vehicular Technology Conference, 1999. VTC 1999 - Fall. IEEE VTS 50th, New York: IEEE , 1999, p. 1653-1657Conference paper (Refereed)
    Abstract [en]

    Emerging multimedia services in cellular radio systems introduce a variable transmission rate, which raises the problem of controlling transmission rates in a spectrally efficient way. We formulate the problem into a combined power and rate control, for which we suggest two different algorithms. In the first one, we derive an algorithm applying the Lagrangian relaxation technique. In the other method, called selective power control we extend a fixed rate power control algorithm to solve the problem. Computational experiments carried out on a CDMA system indicate that the proposed algorithms give satisfying performance in terms of system throughput, outage probability and transmission power consumption.

  • 75.
    Koo, Insoo
    et al.
    Dept. of Infor. and Comm., Gwang-Ju Institute of Science and Technology, 1 Oryong-dong, Puk-gu, Gwangju, 500-712, Korea.
    Furuskär, Anders
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Zander, Jens
    KTH, Superseded Departments, Wireless at KTH.
    Kim, Kiseon
    Dept. of Infor. and Comm., Gwang-Ju Institute of Science and Technology, 1 Oryong-dong, Puk-gu, Gwangju, 500-712, Korea.
    Erlang Capacity Analysis of Multi-access Systems Supporting Voice and Data Services2004In: PERSONAL WIRELESS COMMUNICATIONS, PROCEEDINGS, Berlin: Springer , 2004, p. 643-645Conference paper (Refereed)
    Abstract [en]

    In this paper, we analyze and compare the Erlang capacity ofmulti-access systems supporting several different radio access technologies according to two different operation methods: separate and common operation methods. In the common operation, any terminal can connect to any sub-system while each terminal in the separate operation only can connect to its designated sub-system. In a numerical example withGSM/EDGE-like and WCDMA-like sub-systems, it is shown that wecan get up to 60% Erlang capacity improvement through the common operation method when using a near optimum so-called service-based user assignment scheme. Even with the worst-case assignment scheme, we can still get about 15% capacity improvement over the separate operation method.

  • 76.
    Koo, Insoo
    et al.
    Dept. of Infor. and Comm., Gwang-Ju Institute of Science and Technology, 1 Oryong-dong, Puk-gu, Gwangju, 500-712, Korea.
    Furuskär, Anders
    KTH, Superseded Departments, Wireless at KTH.
    Zander, Jens
    KTH, Superseded Departments, Wireless at KTH.
    Kim, Kiseon
    Dept. of Infor. and Comm., Gwang-Ju Institute of Science and Technology, 1 Oryong-dong, Puk-gu, Gwangju, 500-712, Korea.
    Erlang Capacity of Multi-Access Systems with Service-based Access Selection2004In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 8, no 11, p. 662-664Article in journal (Refereed)
    Abstract [en]

    In this letter, we provide the lower and upper bounds of Erlang capacity of multi-access systems supporting several different radio access technologies in the multi-service scenario, by considering two extreme operation methods; separate and common operation. In a numerical example with GSM/EDGE-like and WCDMA-like sub-systems, it is shown that the common operation method can provide up to 60% Erlang capacity improvement over the separate operation method when using a near optimum so-called service-based user assignment scheme, with the combined effects of the assignment and the trunking gains. Even in the worst-case, the common operation method still can provide about 15% capacity improvement over the separate operation method, which mainly comes from the trunking gain.

  • 77.
    Ligeti, Agnes
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Cost Coverage Planning for Single Frequency Networks1999In: IEEE transactions on broadcasting, ISSN 0018-9316, E-ISSN 1557-9611, Vol. 45, no 1, p. 78-87Article in journal (Refereed)
    Abstract [en]

    OFDM based single frequency networks (SFNs) have been standardized for terrestrial broadcasting systems, for digital audio broadcasting (DAB) as well as for digital video broadcasting (DVB). Due to the multipath tolerance of the OFDM scheme, the receiver is able to combine signals coming from several transmitters, despite of the varying propagation delays, i.e., heavy artificial multipath propagation. In order to take full advantage of the diversity gain provided by the SFN architecture, proper network design is required. We focus on the cost efficient design of an SFN providing broadcasting services over a predefined service area with requirements both on the received signal quality and on the allowable interference level experienced by existing services in the same spectrum. We formulate the problem as a discrete optimization problem, where the network design parameters such as power, antenna heights and transmitter locations are the decision variables. The general stochastic optimisation algorithm simulated annealing has been adapted for solving the above problem. The novelty of our method is that cost factors and interference constraints are embedded in the optimisation procedure. Through numerical examples we demonstrate that significant reduction in network cost can be achieved by our approach.

  • 78.
    Lindström, Magnus
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Badia, L.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zorzi, N.
    Speculative resource allocation for packet-switched wireless networks2005In: VTC2005-SPRING: 2005 IEEE 61ST VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, PROCEEDINGS, 2005, p. 1451-1455Conference paper (Refereed)
    Abstract [en]

    In this paper we study benefits of speculative scheduling in wireless networks with elastic services. Common goals of Radio Resource Management (RRM) have traditionally been maximisation of throughput and provisioning of QoS guarantees. Providers of wireless access, however, need to acquire adequate revenue to sustain their business. While throughput maximisation and QoS guarantees increase the quantity or quality, respectively, of the chargeable goods, it has also been shown that by accounting for users' perceptions of what is acceptable from QoS and pricing perspective, provider revenue may increase. We propose and evaluate a packet scheduler for realtime streaming services with the aim to maximise user satisfaction and, thus, improve operator revenue. We also extend an existing service acceptance probability model with a service continuation probability model. The proposed scheduling scheme is compared to a proportional fair scheduler. Preliminary results show that revenue can be increased significantly, while keeping user satisfaction approximately constant. Alternatively, the user satisfaction can be correspondingly improved for fixed revenue.

  • 79.
    Lindström, Magnus
    et al.
    KTH, School of Electrical Engineering (EES).
    Badia, Leonardo
    University of Ferrara.
    Zander, Jens
    KTH, School of Electrical Engineering (EES).
    Zorzi, Michele
    University of Ferrara.
    Spececulative Admission Control and Scheduling for Packet-Switched Wireless Networks2005In: IEEE Journal on Special Areas in Communications, Special issue: Price-Based Access Control and Economics for Communication NetworksArticle in journal (Refereed)
  • 80.
    Lindström, Magnus
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Dynamic link asymmetry in `bunched' wireless networks.1999In: Vehicular Technology Conference, 1999. VTC 1999 - Fall. IEEE VTS 50th, 1999, p. 352-356Conference paper (Refereed)
    Abstract [en]

    In most future wireless applications an increasing fraction of the total offered traffic is expected to appear in the downlink (fixed-to-mobile) segment of the system. This requirement matches rather poorly with the system design and spectrum allocation for current and future systems which employ symmetric frequency division duplex (FDD). In contrast, TDMA/TDD systems, at least in principle, allow for a more flexible resource allocation by moving the boundary between uplink and downlink time-slots, the switching point. The key problem caused by moving the switching point; is interference between mobiles and base stations. In the paper, some algorithms to select and adapt the switching point in a `bunched' cellular environment are investigated. A simple scheme using a `soft' switching point, is shown to provide a capacity, while not as high as a fully dynamic scheme, still considerably higher than the capacity of a traditional fixed switching point scheme. Further, the `soft' scheme is also adaptive, in the sense that it tracks varying traffic asymmetry ratios.

  • 81. Lou, Jiang
    et al.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Performance analysis in HF-communication Networks using Packet switching1992In: Nordic Shortwave Conference Hf-92, 1992Conference paper (Refereed)
  • 82.
    Lungaro, Pietro
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    ActiveCast - a network and user aware mobile content delivery system2010In: Ubiquitous and Future Networks (ICUFN), 2010 Second International Conference on, IEEE , 2010, p. 309-313Conference paper (Refereed)
    Abstract [en]

    Most of the currently deployed networks are typically dimensioned considering the "peak hour" traffic demand. Opportunistically utilizing these "excess" resources might be an effective way for improving utilization and lowering the "production" costs. This paper is proposing and evaluating a novel concept, called ActiveCast, and the corresponding architecture for a network and user behavior aware mobile content delivery system. When considering real traffic measurements in urban scenarios we showed that the concept improves the resource utilization and allows serving significantly more users in a pre-existing network. Even with moderate amounts of reliable context information, ActiveCast have been shown to drastically improving both user quality of experience perception and network efficiency, as compared to conventional on-demand content delivery schemes.

  • 83.
    Lungaro, Pietro
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Context-aware RRM for opportunistic content delivery in cellular networks2010In: 3rd Int. Conf. on Communication Theory, Reliability, and Quality of Service, CTRQ 2010, Includes MOPAS 2010: 1st Int. Conf. on Models and Ontology-Based Design of Protocols, Architecture and Services, 2010, p. 175-180Conference paper (Refereed)
    Abstract [en]

    To opportunistically exploit excess resources avail-able at different times and locations we propose in this paperto include context aware information in the RRM schemesadopted in cellular networks. Both an user and a network centricapproaches to content pre-fetching are described and evaluatedfor different network dimensioning and service scenarios. Theobtained results show that for different levels of accuracyin predicting future content requests, operator controlled pre-fetching outperforms the user controlled approach, and that theformer can also bring robustness and significant cost reductionas compared to “classical” RRM schemes: the achieved level ofperformances can be mapped into a tri-dimensional gain regionwhere fewer BSs are needed, or more users can be served, orlarger files delivered per user, while maintaining a given levelof user-perceived service quality. Finally, considering also thedeployment of content caches at the BSs we show that the impactof backhaul limitations on experienced delays can be furthermitigated, when there are similar content interests among users.

  • 84.
    Lungaro, Pietro
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    ContextShift: a Model for EfficientDelivery of Content in MobileNetworks2010In: Wireless Communications & Networking Conference, 2010Conference paper (Refereed)
    Abstract [en]

    A context aware model for delivery of content inmobile networks is introduced and studied through simulation.The model is based on predictive knowledge of mobile userand mobile group behavior. The predictive behavior is relatedto consumption of mobile content on smart mobile terminals.The model proposes to change the time and the location ofthe delivery of predicted content consumption to optimize thewireless network utilization and to improve the user experience.Different content delivery strategies, considering pre-fetchingat the user terminals, caching at the base stations and multi-cast wireless transmissions are proposed and investigated. Thesimulation results show substantial gains in the content deliveryefficiency of cellular networks and improved user perceivedquality for a number of realistic network operation regimes.

  • 85.
    Lungaro, Pietro
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Predictive and Context-based Multimedia Content Delivery inFuture Cellular Networks2010In: 2010 IEEE 71ST VEHICULAR TECHNOLOGY CONFERENCE, 2010Conference paper (Refereed)
    Abstract [en]

    A context aware model for the delivery of contentin mobile networks is presented and studied through simulation.The proposed model is based on predictive knowledge of mobileuser behavior related to consumption of content on smartterminals. Content prediction is here exploited to change the timeand the location of content delivery, opportunistically utilizing theinstantaneously available excess of resources in the network. Thisis anticipated both to increase network utilization and to enhanceuser perceived service quality. However, since the accuracy of thecontext information, and associated content predictions, mighthave a significant impact on performances, our investigationshave been accounting for different content prediction capabilitiesas well as for various degrees of similarity in users’ contentrequests. The obtained results show that substantial gains bothin terms of wireless network efficiency and improved user serviceperception can be achieved, as compared to classical contentdelivery methods, for a number of realistic scenarios.

  • 86.
    Maguire Jr., Gerald Q.
    et al.
    KTH, Superseded Departments, Teleinformatics.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Tenhunen, Hannu
    KTH, Superseded Departments, Electronic Systems Design.
    Zander, Jens
    KTH, Superseded Departments, Teleinformatics.
    Future Wireless Computing & Communications1994In: NRS-Seminarium Radiokommunikationsnät Konferensdokumentation, 1994, p. 57-61Conference paper (Refereed)
    Abstract [en]

    With the advent of mass produced cellular telephony, wireless communication is about to revolutionize the way we think about information systems. In the near future it is generally believed that entertainment, personal computing and communication industries will merge and that the organizations and consumers will demand their services `on the move´. This paper will address how new technologies will enable future mobile distributed computing and communication systems and discuss what their impact may be on the behavior of users and their organizations. We will focus on some important trends in future mobile[21] and wearable/implantable computing[10]. Some of the limiting factors and key research and engineering problems are outlined. This paper demonstrates that future wireless applications and systems have to cope with a wide variety of heterogenous infrastructures ranging from short range local area high speed (100Mbit/s) systems to low speed long range and wide area satellite based systems.

  • 87.
    Miao, Guowang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Slimane, Slimane Ben
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Fundamentals of Mobile Data Networks2016Book (Other academic)
    Abstract [en]

    This unique text provides a comprehensive and systematic introduction to the theory and practice of mobile data networks. Covering basic design principles as well as analytical tools for network performance evaluation, and with a focus on system-level resource management, you will learn how state-of-the-art network design can enable you flexibly and efficiently to manage and trade-off various resources such as spectrum, energy, and infrastructure investments. Topics covered range from traditional elements such as medium access, cell deployment, capacity, handover, and interference management, to more recent cutting-edge topics such as heterogeneous networks, energy and cost-efficient network design, and a detailed introduction to LTE (4G). Numerous worked examples and exercises illustrate the key theoretical concepts and help you put your knowledge into practice, making this an essential resource whether you are a student, researcher, or practicing engineer.

  • 88.
    Monti, Paolo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tombaz, Sibel
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Mobile backhaul in heterogeneous network deployments: Technology options and power consumption2012In: 14th International Conference on Transparent Optical Networks, 2012, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Mobile communication networks account for 0.5% of the global energy consumption, a value that is expected to double within the next five years. For this reason, means of reducing the energy consumption in cellular mobile radio networks has recently gained great interest within the research community. In mobile networks the backhaul contribution to the total power consumption is usually neglected because of its limited impact compared to that of the radio base stations. However, meeting the almost exponential increase in mobile data traffic requires a large number of (mainly small) base stations. This means that backhaul networks will take a significant share of the cost and the energy consumption in future systems. Their actual contribution to the energy consumption will depend on the radio base station deployment scenario as well as on the technology and topology choices for the backhaul itself. This paper presents an initial assessment of the power consumption of two established backhaul technologies, i.e., fiber and microwave. For the microwave case, three backhaul topologies are considered, i.e., tree, ring and star, while for the fiber case only one topology is analysed, i.e., a dedicated point-to-point star. The presented results, assuming off-the-shelf products and based on todays network capacity levels, confirm the importance of considering the backhaul when minimizing the total power consumption in heterogeneous network scenarios. They also show the impact of the basic technology and topology choices of the backhaul for minimizing total power consumption.

  • 89.
    Niebert, Norbert
    et al.
    Department Manager, Ericsson Research, Germany.
    Schieder, Andreas
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Hancock, Robert
    Ambient Networks: Co-Operative Mobile Networking for the Wireless World2007Book (Refereed)
    Abstract [en]

    Ambient Networks defines a new kind of network architecture, which embeds support for co operation and competition between diverse network types within a common control layer. This unified networking concept can adapt to the heterogeneous environments of different radio technologies and service and network environments. Special focus is placed on facilitating both competition and co-operation of various market players, by defining interfaces which allow the instant negotiation of cooperation agreements. The Ambient Networking concept has been developed in the framework of the Ambient Networks project, which is co-sponsored by the European Union under the Information Society Technology (IST) priority of the 6th Framework Programme. The Ambient Networks project mobilised the work of researchers from over forty different organisations, both major industrial corporations and leading academic institutions, from Europe and worldwide. This book offers a complete and detailed overview of the Ambient Networking concept and its core technologies. The authors explain the problems with current mobile IP networks and the need for a new mobility-aware IP-based control architecture, before presenting the Ambient Networking concept itself and the business opportunities that it offers. The architecture, components, features and challenges of Ambient Networking are covered in depth, with comprehensive discussions of multi-radio access, generic Ambient Network signalling, mobility support, context and network management and built-in media delivery overlay control. Ambient Networks: Co-operative Mobile Networking for the Wireless World Explains the need for Ambient Networking, discussing the limitations of today's proposed architectures, and explaining the business potential of edge networks and network co-operation. Describes Ambient Networking technology in detail, and addresses the technical challenges for implementation. Includes practical user scenarios which are fully analysed and assessed through simulation studies. Including a complete examination of the research and technologies arising from the Ambient Networks concept, Ambient Networks will be invaluable for research and development teams in networking and communications technology, as well as advanced students in electrical engineering and computer science faculties. Standardisation specialists, research departments, and telecommunications analysts will also find this a helpful resource.

  • 90.
    Obayashi, Shuishi
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    A deterministic man-made shadowing model for indoor radio communication environment1996In: Antennas and Propagation Society International Symposium, 1996. AP-S. Digest, 1996, p. 433-436Conference paper (Refereed)
    Abstract [en]

    A new man-made shadowing model was proposed. This model enables us to estimate deterministically the man-made shadowing effects, which are one of the dominant factors with indoor radio communication. The model can be used with the numerous propagation prediction methods based on ray prediction. Moreover, it allows the selection of appropriate locations and antenna characteristics for macroscopic diversity branches for the base station. The increase in loss due to man-made shadowing is a function of frequency, polarization, antenna height, etc.

  • 91.
    Obregon, Evanny Carol
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Is spectrum sharing in the radar bands commercially attractive?: -a regulatory and business overview2016In: European transactions on telecommunications, ISSN 1124-318X, E-ISSN 2161-3915, Vol. 27, no 3, p. 428-438Article in journal (Refereed)
    Abstract [en]

    The need to meet users' expectations in the 'mobile data avalanche' represents a significant challenge for mobile network operators. More spectrum is a natural way to meet these requirements in a cost and time-efficient way, but new, exclusively licenced spectrum is increasingly hard to come by. Instead, vertical spectrum sharing has been discussed as a potential solution for finding additional spectrum. In this paper, we focus on vertical spectrum sharing in the radar bands for providing short-range wireless access, for example, indoors and in hotspots that 'offload' traffic demand. We propose a methodology for analysing the technical, regulatory and business aspects of deploying large-scale wireless networks. Then, we identify the following criteria for achieving business success: spectrum availability, availability of low-cost end-user devices, system scalability in terms of number of concurrently used devices and finally the ability to guarantee a quality of service for the users. Our technical availability assessment has identified geo-location database as the necessary technical enabler and detect-and-avoid mechanism as an auxiliary enabler for improving sharing conditions. Moreover, licenced shared access was found to be the suitable regulatory framework to support the proposed sharing mechanism and regulatory policies in real-life implementation. Our business feasibility assessment concludes that there is enough spectrum available for indoor and hotspots communication in urban areas in the radar bands to make a large-scale system commercially viable. Service quality can be guaranteed, and there is a strong potential to construct low-cost devices. Uncertainties do, however, remain regarding the spectrum access cost.

  • 92.
    Obregon, Evanny
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Shi, Lei
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Ferrer Coll, Javier
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    A model for Aggregate Adjacent Channel Interference in TV White Space2011In: IEEE Vehicular Technology Conference, 2011, p. 1-5Conference paper (Refereed)
    Abstract [en]

    The presence of white spaces and spectrum holes in the TV bands represents potential opportunities for alleviating the apparent spectrum scarcity. Opportunistic spectrum access (OSA) has been proposed for the secondary user's operation and the main concern is the harmful interference that secondary systems could cause to the primary receivers. Existing studies have focused on establishing the limits for co-channel and adjacent channel interference when only one adjacent channel is used by a single secondary user. This paper presents a characterization of the aggregate adjacent channel interference (AACI) when different adjacent channels are simultaneously accessed by multiple secondary users or white space devices (WSDs). An analytical expression is proposed to approximate the limits of the tolerable AACI. Our model states that not only the interference received in each adjacent channel should stay below the corresponding threshold for that particular channel, but also the weighted sum of the total adjacent channel interference power should be kept below a certain threshold. Measurement campaigns show the cumulative effect of the adjacent channel interference (ACI) when multiple WSDs access multiple adjacent channels at the same time. The proposed analytical expression for AACI closely matches the measurement results.

  • 93.
    Obregon, Evanny
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Shi, Lei
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Ferrer Coll, Javier
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Experimental Verification of Indoor TV White Space Opportunity Prediction Model2010In: 2010 5th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCom 2010, 2010Conference paper (Refereed)
    Abstract [en]

    Recent work has demonstrated that the underutilized spectrum in the Digital Television Bands, commonly referred to as TV White Space (TVWS), is a prime candidate for opportunistic spectrum access (OSA). However, a systematic assessment of the availability of this spectrum for secondary transmission was, until very recently, lacking. In a TVWS opportunity prediction model to estimate indoor secondary usage probability was proposed. In this paper we aim at verifying this model by means of measurement campaigns in both laboratory and real indoor environments. The match between the predictions from the simulation models in and measurement results suggest that the model provides a realistic evaluation of the opportunities in TVWS for low power indoor secondary usage.

  • 94.
    Obregon, Evanny
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Availability Assessment of Secondary Usage in Aeronautical Spectrum2013In: 2013 IEEE Wireless Communications and Networking Conference (WCNC), IEEE Communications Society, 2013, p. 4510-4515Conference paper (Refereed)
    Abstract [en]

    In this paper, we provide a quantitative assessment of the available spectrum for massive indoor broadband secondary access in the 960-1215 MHz band, primarily allocated to the distance measuring equipment (DME) systems. We employ a practical sharing scheme where the secondary users share the DME spectrum via geo-location database and spectrum sensing. Since the DME system performs a safety-of-life functionality, protection from harmful interference becomes extremely critical. A DME channel is considered available in a certain time and location if the secondary users, under the applied sharing scheme, are able to successfully access the channel without violating the primary protection criteria. We analyze the impact of the secondary system parameters and the potential uncertainties in the applied sharing mechanism on the availability in the DME band. Numerical results show that at least 30% of the total DME band (57 MHz out of 190 MHz) can be available for a dense low-power indoor secondary network, even if conservative primary system protection criteria and high levels of uncertainty are considered.

  • 95.
    Obregon, Evanny
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Is Spectrum Sharing in the Radar Bands Commercially Attractive?: A Regulatory and Business OverviewIn: Telecommunications Policy, ISSN 0308-5961, E-ISSN 1879-3258Article in journal (Other academic)
    Abstract [en]

    The need to meet users’ expectations in the ”mobile data avalanche” represents a significant challenge for mobile networks operators (MNOs). More spectrum is a natural way to meet these requirements in a cost and time-efficient way; but new, exclusively licensed, spectrum is increasingly hard to come by. Instead, vertical spectrum sharing has been discussed as a potential solution for finding additional spectrum for mobile communications. In this paper, we focus on vertical spectrum sharing in the radar bands for providing short-range wireless access, e.g. indoors and in ”hotspots” that ”offload” mobile traffic demand. We propose a methodology for dealing with the technical, regulatory and business aspects of deploying large-scale wireless networks. Moreover, we identify the following criteria for achieving business success: spectrum availability, availability of low-cost end user devices, system scalability in terms of number of concurrently used devices and finally, the ability to guarantee a quality of service for the users.

    Our technical availability assessment has identified geo-location database support as necessary technical enabler and detect-and-avoid mechanism as a beneficial technical enabler for improving sharing conditions. Therefore, we propose a sharing mechanism based on three components: a central spectrum manager witha geo-location database controlling the aggregate interference, a spectrum sensing mechanism and a fast feedback between the radars and the central spectrum manager. Moreover, Licensed Shared Access (LSA) was found to be the suitable regulatory framework to support the proposed sharing mechanism and regulatory policies in real-life implementation. Our business feasibility assessment concludes that there is enough spectrum available for indoor and hotspots communication in urban areas in the radar bandsto make a large scale system commercially viable. Service quality can be guaranteedand there is a strong potential to construct low-cost devices. Uncertainties do, however, remain regarding the spectrum access cost.

  • 96.
    Obregon, Evanny
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    On the Feasibility of Indoor BroadbandSecondary Access to the 960-1215 MHz Aeronautical Spectrum2013In: Transactions on Emerging Telecommunications Technologies, ISSN 2161-3915, Vol. 24, no 7-8, p. 724-733Article in journal (Refereed)
    Abstract [en]

    In this paper, we analyse the feasibility of indoor broadband service provisioning using secondary spectrum access to the 960–1215 MHz band, primarily allocated to the distance measuring equipment (DME) system for aeronautical navigation. We propose a practical secondary sharing scheme customised to the characteristics of the DME. Because the primary system performs a safety-of-life functionality, protection from harmful interference becomes extremely critical. The proposed scheme controls aggregate interference by imposing an individual interference threshold on the secondary users. We examine the feasibility of large scale secondary access in terms of the transmission probability of the secondary users that keeps the probability of harmful interference below a given limit. Uncertainties in the estimation of propagation loss and DME location affect the feasibility of the secondary access. Numerical results show that a large number of secondary users are able to operate in adjacent DME channels without harming the primary system even with limited accuracy on the estimation of the propagation loss.

  • 97.
    Obregon, Evanny
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    On the Sharing Opportunities for Ultra-Dense Networks in the Radar Bands2014In: 2014 IEEE International Symposium on Dynamic Spectrum Access Networks, DYSPAN 2014, IEEE Computer Society, 2014, p. 215-223Conference paper (Refereed)
    Abstract [en]

    Finding additional spectrum for indoor networks with very high capacity (ultra-dense networks, UDN) is a prime concern on the road to 5G wireless systems. Spectrum below or around 10 GHz has attractive propagation properties and previous work has indicated that vertical spectrum sharing between indoor users and outdoor wide-area services is feasible. In this paper, we focus on spectrum sharing between UDNs and radar systems. We propose and evaluate regulatory policies that improve sharing conditions/opportunities in areas with large demand (i.e. hot-spots and urban areas). We consider three regulatory policies: area power regulation, deployment location regulation and the combination of these. We address the scenario where secondary users can reliably exploit time and space domain sharing opportunities in the S- and Ku-Bands by means of geo-location databases and spectrum sensing. We evaluate these opportunities in terms of the required time-averaged separation distance between the radar system and the UDN that both protects the radar system as well as guarantees a minimum secondary transmission probability. Our results show that there are ample adjacent channel sharing opportunities for indoor usage in both the S- and Ku-Bands. In the Ku-Band, even outdoor hot-spot use is feasible with very relaxed restrictions. Co-channel usage in the S-band requires large separation distances that makes it practically unfeasible in cities with nearby radar sites. Overall, deployment location regulation seems to be the most effective means to limit interference to the radar system and improve sharing opportunities. 

  • 98.
    Obregon, Evanny
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Secondary Access to the Radar Spectrum Bands: Regulatory and Business Implications2013Conference paper (Refereed)
    Abstract [en]

    The large expected increase in the capacity requirements raises not only technical issues but also regulatory and business challenges. One of the key methods to increase the capacity of mobile networks in a cost efficient way is to find additional frequency spectrum. However, it is a difficult task since most of the spectrum is already allocated in long-term basis. Therefore, innovation in the technical and regulatory domain is needed to make additional spectrum available for mobile communications that not only improve spectrum utilization but also to make long-term investments feasible. Secondary spectrum access was proposed as a technical solution to improve spectrum utilization. However, uncertainties on the regulatory regime have been the main “show-stopper” for long-term investments.  This paper has devised techno-regulatory conditions for making large-scale secondary access to the "radar bands" an attractive business scenario from the MNO's perspective. Our numerical results showed that applying regulation on the deployment of secondary users can significantly improve sharing opportunities, especially in lower frequency bands (S-band) where the impact of interference aggregation is higher. We also identified Licensed Shared Access (LSA) as suitable authorization model for secondary access to the "radar bands" since it provides the level of reliability on the protection against harmful interference and it could also motivate long-term investments. Finally, establishing the right spectrum access cost or license fee for secondary access to the "radar bands" is crucial for achieving competitive edge over alternatives indoor solutions.

  • 99.
    Obregon, Evanny
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Short Range White Space Utilization in Broadcast Systems for Indoor Environments2010In: IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN), IEEE , 2010Conference paper (Refereed)
    Abstract [en]

    As Digital Television Broadcasting spreads over theworld, existing (and more) TV channels can be distributed in lessspectrum in the spectrum traditionally allocated to TVbroadcasting. This freed spectrum is also referred to as the "DigitalDividend" and its use has been debated around the world. Inaddition, there is also a debate about the potential use of the “whitespace” within the TV-bands. This is due to the sparse frequencyplanning with large interference margins, which is typical in widearea broadcasting. Various technical approaches using Opportunistic Spectrum Access(OSA) have been proposed for unlicensed “white space” access tothe TV bands. Most of previous studies have focused on spectrumsensing, i.e. detecting “free channels”, where secondary users,utilizing White Space Devices (WSD) could avoid causing harmfulinterference to the TV receivers. However, interference caused byWSD is not only limited to co-channel interference. In particular, inshort-range scenarios, the adjacent channel interference is anequally severe problem. Assessing the feasibility of WSDs in shortrangeindoor scenarios, taking more interference mechanisms intoaccount is the objective of this paper. An Indoor home scenariowith Cable, Rooftop antenna and Set-top antenna reception ofDVB-T, has been analyzed. The spectrum reuse opportunities forWSDs have been determined, using the number of channels whereit is possible to transmit without causing harmful interference toDVB-T receivers as performance measure. Simulation results showthat the number of available channels for indoor unlicensed whitespace transmission appears to be significant in most of the studiedscenarios.

  • 100.
    Ozyagci, Ali
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    An empirical aggregate throughput model for dense WLANsManuscript (preprint) (Other academic)
    Abstract [en]

    Due to the popularity of WLANs based on the IEEE 802.11 standard, these WLANs are being deployed in close proximity of each other in urban office and residential environments. This dense deployment of WLANs, in combination with the complex indoor propagation environment created by walls, make the performance analysis of such a system of WLANs difficult. Existing WLAN throughput models cannot accurately represent the aggregate throughput performance of these systems. Performing a packet-level analysis of each system of WLANs would be accurate but costly in time and computational resources. In this work, we propose an empirical aggregate throughput model for a system of densely deployed WLANs based on a comprehensive simulation analysis of such WLANs using OPNET. Our proposed model can estimate the throughput performance of a system of WLANs with fairly good accuracy in a range of propagation environments, deployment densities, deployment and association types.

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