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  • 1.
    Ahmed, Ashraf
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Yang, Yanpeng
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Won Sung, Ki
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Markendahl, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    On the Engineering Value of Spectrum in Dense Mobile Network Deployment Scenarios2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    the continuing growth in the mobile data traffic magnifies the challenges for the design and deployment of scalable high-capacity mobile networks that can meet the future demand at reasonable cost levels. In order to meet the future traffic demand, an operator should invest on both infrastructure, i.e. densification of base stations, and more radio spectrum. Knowing the effectiveness of each element is thus of utmost importance for minimizing the investment cost. In this paper, we study the economic substitutability between spectrum and densification. For this, we measure the engineering value of spectrum, which refers to the potential saving in the total cost of ownership (TCO) as result of acquiring additional spectrum resources. Two countries are considered to represent different market situations: India with dense population and high spectrum price and Sweden with moderate population density and low spectrum fee. Numerical results indicate that additional amount of spectrum substantially relieves the need for densifying radio base stations, particularly for providing high user data rate in dense India. Nonetheless, the engineering value of spectrum is low in India (i.e. spectrum acquisition has less cost benefit) under the high spectrum price of today, whereas spectrum is instrumental in lowering the total cost of ownership in Sweden. Our finding highlights the importance of affordable and sufficient spectrum resources for future mobile broadband provisioning.

  • 2.
    Kim, Donggu
    et al.
    Korea Adv Inst Sci & Technol, Sch Elect Engn, Daejeon 34141, South Korea..
    Yang, Yanpeng
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Sung, Ki Won
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Kang, Joonhyuk
    Korea Adv Inst Sci & Technol, Sch Elect Engn, Daejeon 34141, South Korea..
    Cooperation Strategies for Partly Wireless C-RAN2018Ingår i: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 22, nr 6, s. 1248-1251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This letter presents a variant of cloud radio access network (C-RAN) architecture, which we term partly wireless C-RAN (PW-CRAN). It is characterized by extra radio nodes connected through the existing remote radio heads. Because of the newly connected nodes and the consequent additional delay, the operation of PW-CRAN requires different approaches compared with that of the typical C-RAN. Specifically, the effect of delayed channel state information on the suitability of network cooperation should be identified. To tackle this problem, we introduce two representative cooperation strategies and evaluate the performance with regard to the delay via simulations. Numerical results suggest that it is better to exclude the extra nodes from cooperation if they incur excess delay. Furthermore, whether the delay is deemed excessive depends on the interference environment. Hence, we provide quantified guidelines on the cooperation strategy of PW-CRAN.

  • 3.
    Shokri-Ghadikolaei, Hossein
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Yang, Yanpeng
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Petrova, Marina
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Sung, Ki Won
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Fast and Reliable Initial Cell-search for mmWave Networks2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    In millimeter-wave wireless networks, the use of narrow beams, required to compensate for the severe path-loss, complicates the cell-discovery and initial access. In this paper, we investigate the feasibility of random beam forming and enhanced exhaustive search for cell-discovery by analyzing the latency and detection failure probability in the control-plane and the user throughput in the data-plane. We show that, under realistic propagation model and antenna patterns, both approaches are suitable for 3GPP New Radio cellular networks. The performance gain, compared to the heavily used exhaustive and iterative search schemes, is more prominent in dense networks and large antenna regimes and can be further improved by optimizing the beam forming code-books.

  • 4.
    Yang, Yanpeng
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    A study on the deployment and cooperative operation of ultra-dense networks2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The traffic volume in wireless communication has grown dramatically in the last decade and is predicted to keep increasing in the future. In this thesis, we focus on the densification dimension for capacity improvement, which has been proved to be the most effective in the past. The current gain of network densification mainly comes from cell splitting, thereby serving more user equipments (UEs) simultaneously. This trend will decelerate as base station (BS) density gets closer to or even surpass UE density which forms an ultra-dense network (UDN). Thus, it is crucial to understand the behavior of ultra-densification for future network provisioning.

     

    We start from comparing the effectiveness of densification with spectrum expansion and multi-antenna systems. Our findings show that deploying more BSs provides a substantial gain in sparse network but the gain decreases progressively in a UDN. The diminishing gain appears in a UDN make us curious to know if there exists a terminal on the way of densification. Such uncertainty leads to the study on the asymptotic behavior of densification. We incorporate a sophisticated bounded dual-slope path loss model and practical UE densities in our analysis. By using stochastic geometry, we derive the expressions and prove the convergence of the coverage probability of a typical UE and network area spectral efficiency (ASE). Considering the large portion of dormant BSs in a UDN, it is an interesting question whether we can utilize these dormant BSs to improve system performance is an interesting question. To this end, we employ joint transmission (JT) techniques into a UDN. Two types of cooperation schemes are investigated: non-coherent JT and coherent JT depending on the availability of channel state information (CSI). Our results reveal that non-coherent JT is not beneficial in a UDN while coherent JT are able to increase UE spectral efficiency (SE) depending on the environmental parameters.

  • 5.
    Yang, Yanpeng
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Ultra-Densification for Future Cellular Networks: Performance Analysis and Design Insights2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The traffic volume in wireless communication has grown dramatically in the lastdecade. Recent predictions indicate such data storm will be even more violent in theshort run. Potential solutions for accommodating the rapid traffic growth can besummed up into three categories: broadening the available bandwidth, improvingthe spectral efficiency, and densifying the infrastructure. In this thesis, we focuson the densification dimension which has been proven to be the most effectiveone in the past. The current gain of network densification mainly comes from cellsplitting, thereby serving more user equipment (UE) simultaneously. This trendwill decelerate as the base station (BS) density gets closer to or even surpassesthe UE density which forms an ultra-dense network (UDN). Thus, it is crucialto understand the behavior and design operations of ultra-densification in futurenetworks.

    An important question for future system design and operating strategy is whichelement is more effective than others. To this end, we start from comparing the effectivenessof densification with spectrum expansion and multi-antenna systems interms of meeting certain traffic demand. Our findings show that deploying more BSsprovides a substantial gain in sparse network but the gain decreases progressively ina UDN. Meanwhile, even with the same area throughput, different combinations ofindividual throughput and UE density lead to different requirements for resources.The diminishing gain appearing in UDNs makes us curious to know if there existsa terminal on the way of densification. Such uncertainty leads to the study onthe asymptotic behavior of densification. By incorporating a sophisticated boundeddual-slope path loss model and practical UE densities in our analysis, we present theasymptotic behavior of ultra-densification: the coverage probability and area spectralefficiency (ASE) have non-zero convergences in asymptotic regions unless theUE density goes to infinity (full load). Our results suggest that network densificationcannot always improve the UE performance or boost the network throughput.

    Next, we shift our focus to the operations of UDNs. We first study BS cooperationsin two UDN scenarios: homogeneous and heterogeneous UDNs which aredistinguished by BS types. In both cases, the cooperation rules become more complicatedthan those in traditional networks. Either channel state information (CSI) orextra delay information needs to be acquired in order to obtain cooperation gains.At last, we investigate the feasibility of applying random beamforming to initialaccess in millimeter-wave (mmWave) UDNs. To our surprise, the simple methodcan provide sufficient performance in both control and data plane, comparing withthe existing schemes. Therefore, it may be unnecessary to develop complex algorithmsfor initial access in future dense mmWave networks. The findings indicatethat UDN may complicate network operations while it may also facilitate the use ofsimple schemes. Our work provides insights into the understanding of the networkdensification and thus paves the way for the operational design of future UDNs.

  • 6.
    Yang, Yanpeng
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Park, Jihong
    Sung, Ki Won
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    On the Asymptotic Behavior of Ultra-Densificationunder a Bounded Dual-Slope Path Loss ModelManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In this paper, we investigate the impact of networkdensification on the performance in terms of downlink signal-tointerference(SIR) coverage probability and network area spectralefficiency (ASE). A sophisticated bounded dual-slope path lossmodel and practical UE densities are incorporated in the analysis.By using stochastic geometry, we derive an integral expressionalong with closed-form bounds of the coverage probability andASE, validated by simulation results. Through these, we providethe asymptotic behavior of ultra-densification. The coverageprobability and ASE have non-zero convergence in asymptoticregions unless UE density goes to infinity (full load). Meanwhile,the effect of UE density on the coverage probability is analyzed.The coverage probability will suffer from decreasing with largeUE densities due to interference fall into the near-field, but it willkeep increasing with lower UE densites. Furthermore, we showthe performance is overestimated without applying the boundeddual-slope path loss model. Our study can give insights on efficientnetwork provisioning in the future.

  • 7.
    Yang, Yanpeng
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Shi, Lei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Zander, Jens
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    On the Capacity of Wi-Fi System in TV White Space with Aggregate Interference Constraint2013Ingår i: Proceedings of the 2013 8th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCOM 2013, IEEE conference proceedings, 2013, s. 123-128Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we present a quantitative assessmentof the performance of a Wi-Fi like system in TV white space andcompare it with the traditional Wi-Fi system in the ISM band.Particular emphasis is given to the constraint on the aggregatesecondary interference on TV reception, which is regarded as thepremise of the link throughput analysis that followed. Numericalevaluation is performed over different scenarios where the TVreceive signal strength, number of unoccupied TV channels, userdensity are varied. Our results show that the primary interferenceconstraint has only significant impact on the secondary systemperformance in rural scenario with low TV receive signalstrength. In other cases, where higher transmit power does notguarantee better performance, the capacity of the system islimited by the secondary self-interference or collisions rather thanthe interference constraint. Therefore, efficient TV White Spaceutilization can be achieved by properly setting the secondarytransmit power adaptive to different environments.

  • 8.
    Yang, Yanpeng
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Sung, Ki Won
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Technical rate of substitution of spectrum in future mobile broadband provisioning2015Ingår i: 2015 IEEE International Symposium on Dynamic Spectrum Access Networks, DySPAN 2015, IEEE conference proceedings, 2015, s. 297-300Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dense deployment of base stations (BSs) and multi-antenna techniques are considered as key enablers for future mobile networks. Meanwhile, spectrum sharing techniques and utilization of higher frequency bands make more bandwidth available. An important question for future system design is which element is more effective than others. In this paper, we introduce the concept of technical rate of substitution (TRS) from microeconomics and study the TRS of spectrum in terms of BS density and antenna number per BS. Numerical results show that TRS becomes higher with increasing user data rate requirement, suggesting that spectrum is the most effective means of provisioning extremely fast mobile broadband.

  • 9.
    Yang, Yanpeng
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Sung, Ki Won
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Tradeoff between spectrum and densification for achieving target user throughput2015Ingår i: IEEE Vehicular Technology Conference, IEEE , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dense deployment which brings small base stations (BS) closer to mobile devices is considered as a promising solution to the booming traffic demand. Meanwhile, the utilization of new frequency bands and spectrum aggregation techniques provide more options for spectrum choice.Whether to increase BS density or to acquire more spectrum is a key strategic question for mobile operators. In this paper, we investigate the relationship between BS density and spectrum with regard to individual user throughput target. Our work takes into account load-dependent interference model and various traffic demands. Numerical results show that densification is more effective in sparse networks than in already dense networks. In sparse networks, doubling BS density results in almost twofold throughput increase. However, in dense networks where BSs outnumber users, more than 10 times of BS density is needed to double user throughput. Meanwhile, spectrum has a linear relationship with user throughput for a given BS density. The impact of traffic types is also discussed. Even with the same area throughput requirement, different combination of user density and individual traffic amount leads to different needs for BS density and spectrum.

  • 10.
    Yang, Yanpeng
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Sung, Ki Won
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Park, J.
    Kim, S. -L
    Kim, K. S.
    Cooperative transmissions in ultra-dense networks under a bounded dual-slope path loss model2017Ingår i: 2017 European Conference on Networks and Communications (EuCNC), Institute of Electrical and Electronics Engineers (IEEE), 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    In an ultra-dense network (UDN) where there are more base stations (BSs) than active users, it is possible that many BSs are instantaneously left idle. Thus, how to utilize these dormant BSs by means of cooperative transmission is an interesting question. In this paper, we investigate the performance of a UDN with two types of cooperation schemes: Non-coherent joint transmission (JT) without channel state information (CSI) and coherent JT with full CSI knowledge. We consider a bounded dual-slope path loss model to describe UDN environments where a user has several BSs in the near-field and the rest in the far-field. Numerical results show that non-coherent JT cannot improve the user spectral efficiency (SE) due to the simultaneous increment in signal and interference powers. For coherent JT, the achievable SE gain depends on the range of near-field, the relative densities of BSs and users, and the CSI accuracy. Finally, we assess the energy efficiency (EE) of cooperation in UDN. Despite costing extra energy consumption, cooperation can still improve EE under certain conditions.

  • 11.
    Yang, Yanpeng
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Sung, Ki Won
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Park, Jihong
    Kim, Seong-Lyun
    Kim, Kwang Soon
    Cooperative Transmissions in Ultra-Dense Networks under a Bounded Dual-Slope Path Loss ModelManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In an Ultra-dense network (UDN) where there aremore base stations (BSs) than active users, it is possible thatmany BSs are instantaneously left idle. Thus, how to utilizethese dormant BSs by means of cooperative transmission is aninteresting question. In this paper, we investigate the performanceof a UDN with two types of cooperation schemes: non-coherentjoint transmission (JT) without channel state information (CSI)and coherent JT with full CSI knowledge. We consider a boundeddual-slope path loss model to describe UDN environments wherea user has several BSs in the near-field and the rest in thefar-field. Numerical results show that non-coherent JT cannotimprove the user spectral efficiency (SE) due to the simultaneousincrement in signal and interference powers. For coherent JT, theachievable SE gain depends on the range of near-field, the relativedensities of BSs and users, and the CSI accuracy. Finally, weassess the energy efficiency (EE) of cooperation in UDN. Despitecosting extra energy consumption, cooperation can still improveEE under certain conditions.

  • 12.
    Yang, Yanpeng
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Sung, Ki Won
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Hybrid Fiber and Microwave Protection for Mobile Backhauling2014Ingår i: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 6, nr 10, s. 869-878Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Several studies have shown that optical-fiber-based backhauling offers a future proof solution to handle rapidly increasing traffic in wireless access networks and outperforms other existing backhauling technologies, such as microwave and copper, in terms of capacity, scalability, and sustainability. However, the deployment cost of fiber infrastructure is relatively high and it may be difficult to provide a cost efficient and flexible protection strategy for a fiber backhauling network. Considering that protection is very important to avoid service interruption in a high-capacity mobile backhauling network, in this paper we propose a hybrid fiber and microwave protection scheme for mobile backhauling based on a passive optical network (PON). The proposed reliable architecture is compatible with any wavelength division multiplexing (WDM)based PON, e. g., pure WDM PON and a hybrid time and wavelength division multiplexing (TWDM) PON, offering high flexibility and relatively low deployment cost. The backup for the feeder fiber is provided by dual homing, while the protection of the distribution section can be established via a microwave connection between two base stations in case high reliability performance is required, e. g., for macrocells covering large service areas. We have carried out an extensive assessment of our approach in terms of connection availability, failure impact, complexity, and flexibility in providing resiliency. We also show a comparison with other existing solutions. The evaluation results confirm that our scheme can achieve relatively high flexibility and reliability performance while maintaining low complexity compared with the existing approaches.

1 - 12 av 12
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  • modern-language-association-8th-edition
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  • en-GB
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  • nn-NB
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  • html
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