Endre søk
Begrens søket
12345 101 - 150 of 201
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 101.
    Liu, Dong
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Wang, Chao
    Tongji Univ, Dept Informat & Commun Engn, Shanghai 201804, Peoples R China.;Univ Exeter, Dept Comp Sci, Exeter EX4 4QF, Devon, England..
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Discontinuous Reception for Multiple-Beam Communication2019Inngår i: IEEE Access, E-ISSN 2169-3536, Vol. 7, s. 46931-46946Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Discontinuous reception (DRX) techniques have successfully been proposed for energy savings in 4G radio access systems, which are deployed on legacy 2GHz spectrum bands with signal features of omnidirectional propagation. In upcoming 5G systems, higher frequency spectrum bands will also be utilized. Unfortunately higher frequency bands encounter more significant path loss, thus requiring directional beamforming to aggregate the radiant signal in a certain direction. We, therefore, propose a DRX scheme for multiple beam (DRXB) communication scenarios. The proposed DRXB scheme is designed to avoid unnecessary energy-and-time-consuming beam-training procedures, which enables longer sleep periods and shorter wake-up latency. We provide an analytical model to investigate the receiver-side energy efficiency and transmission latency of the proposed scheme. Through simulations, our approach is shown to have clear performance improvements over the conventional DRX scheme where beam training is conducted in each DRX cycle.

  • 102.
    Lu, Lu
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Sun, F.
    Xiao, Ming
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kildehöj Rasmussen, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Relay-aided multi-cell broadcasting with random network coding2010Inngår i: 2010 International Symposium on Information Theory and Its Applications, 2010, s. 957-962Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We investigate a relay-aided multi-cell broadcasting system using random network codes, where the focus is on devising efficient scheduling algorithms between relay and base stations. Two scheduling algorithms are proposed based on different feedback strategies; namely, a one-step scheduling algorithm with instantaneous feedback for each redundancy packet; and a multi-step scheduling algorithm with feedback only after multiple redundancy packets. For the latter case, dynamic programming is applied to determine optimal scheduling. Numerical results show that the transmission efficiency of the multi-step algorithm approaches that of the one-step algorithm, but requires significantly less feedback. They both significantly outperform corresponding ARQ and random scheduling approaches.

  • 103.
    Lu, Lu
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Xiao, Ming
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Design and Analysis of Relay-aided Broadcast using Binary Network Codes2011Inngår i: Journal of Communication, ISSN 0021-9916, E-ISSN 1460-2466, Vol. 6, nr 8, s. 610-617Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider a base-station broadcasting a set of order-insensitive packets to a user population over packet-erasure channels. To improve efficiency we propose relay-aided transmission using instantaneously-decodable binary network coding. The proposed coding schemes have the benefits of minimal decoding delay and low complexity. We further analyze the performance of the resulting broadcast schemes, and show that significant improvements in transmission efficiency are obtained as compared to previously proposed ARQ and network-coding-based schemes.

  • 104.
    Lu, Lu
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Xiao, Ming
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Relay-Aided Broadcasting with Instantaneously Decodable Binary Network Codes2011Inngår i: 2011 20TH INTERNATIONAL CONFERENCE ON COMPUTER COMMUNICATIONS AND NETWORKS (ICCCN), IEEE , 2011, s. 1-5Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider a base-station broadcasting a set of order-insensitive packets to a user population over packet-erasure channels. To improve efficiency we propose a relay-aided transmission scheme using instantaneously-decodable binary network coding. Our proposed scheme ensures that a coded packet can be immediately decoded at the user side without delay. Moreover, only binary operations are required in the encoding and decoding processes, which decrease the computational complex. We further analyze the performance of the resulting broadcast scheme, and show that significant improvements in transmission efficiency are obtained as compared to previously proposed ARQ and network-coding-based schemes.

  • 105.
    Lu, Lu
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Xiao, Ming
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Efficient Scheduling for Relay-Aided Broadcasting with Random Network Codes2011Inngår i: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC), New York: IEEE , 2011, s. 1815-1819Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We investigate efficient scheduling algorithms for a relay-aided broadcasting system using random network codes, where our objective is to maximize the transmission efficiency. The broadcast from a base-station (BS) is divided into an information phase and a redundancy phase, where the half-duplex relay assists in the redundancy phase. Time-division transmission is used over packet-erasure channels, where the erasure probabilities of the BS-to-relay and relay-to-user links are lower than the BS-to-user links. Following the information phase, each user provides feedback on the status of received packets to the BS and the relay, which in turn both generate redundancy packets for the redundancy phase. To improve efficiency, we formulate a scheduling problem for the transmissions of redundancy packets from the BS and the relay. We consider two scenarios; namely instantaneous feedback after each redundancy packet, and feedback after multiple redundancy packets. In the first case the schedule is determined using a greedy algorithm, while in the second case the schedule is determined using dynamic programming. To determine the performance with instantaneous feedback, we develop an analytic approach based on a Markov chain. Numerical results show that the transmission efficiency of the dynamic programming algorithm is close to the performance of the greedy algorithm, but requires significantly less feedback.

  • 106.
    Lu, Lu
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Xiao, Ming
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kildehöj Rasmussen, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Wu, G.
    Li, S.
    Efficient network coding for wireless broadcasting2010Inngår i: IEEE Wireless Communications and Networking Conference, WCNC, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    It has been shown in the literature that network coding can improve the transmission efficiency of wireless broadcasting as compared to traditional ARQ schemes. In this paper, we propose an improved network coding scheme that can asymptotically achieve the theoretical lower bound on transmission overhead for a sufficiently large number of information blocks. The proposed scheme makes use of an index allocation algorithm that distributes information blocks that have been erased during transmission into a minimum number of encoding sets , where each set represents the erased blocks to be jointly network encoded and retransmitted. Numerical results show that the proposed scheme enables higher transmission efficiencies than traditional ARQ, and previously proposed networks coding schemes for wireless broadcasting.

  • 107.
    Lu, Lu
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Xiao, Ming
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Wu, G.
    Li, S.
    Efficient wireless broadcasting based on systematic binary deterministic rateless codes2010Inngår i: IEEE International Conference on Communications, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We investigate the design and use of systematic binary deterministic rateless (BDR) codes for information transmission over block-erasure broadcast channels. BDR codes are designed to obtain a level of maximal distance separable (MDS) properties, making these codes ideal for the considered broadcast scenario. For a certain number of encoded redundancy blocks, we derive an expression for the probability that the MDS properties are maintained. Moreover, if limited feedback is available, we extend the BDR coding protocol to further improve the system performance. Numerical results show that for a finite number of source blocks and as the number of users grows the proposed systematic BDR codes performs significantly better than LT codes. The proposed schemes with feedback have better performance than traditional ARQ schemes.

  • 108.
    Milner, Rob
    et al.
    University of South Australia.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    Weighted extrinsic feedback in the iterative multiuser decoding of coded CDMA2006Inngår i: 7th Australian Communications Theory Workshop 2006, Proceedings / [ed] Hanlen, LW; Johnson, SJ; Teal, PD, IEEE , 2006, s. 60-65Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In iterative decoding it is well accepted that extrinsic information is to be exchanged between full-complexity soft-input, soft-output constituent decoder components. It is, however, still an open problem to determine the optimal information for exchange between reduced complexity decoder components that are only approximating posterior probabilities. In this paper we investigate the use of weighted extrinsic feedback in iterative multiuser decoding for coded code-division multiple-access (CDMA) systems. The case of no extrinsic feedback corresponds to the conventional approach of exchanging extrinsic information, while full extrinsic feedback corresponds to exchanging a posteriori information. Weighted extrinsic feedback offers a trade-off between the two extreme cases, which can provide significant improvements. These improvements are demonstrated through simulation of an iterative multiuser decoder using parallel interference cancellation as the soft-input, soft-output multiuser detector.

  • 109.
    Milner, Robert
    et al.
    University of South Australia.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    Brännström, Fredrik
    Chalmers University of Technology.
    Recursive LLR combining in iterative multiuser decoding of coded CDMA2007Inngår i: Australian Communication Theory Workshop, 2007, s. 104-109Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Due to the prohibitive complexity of optimal multiuserdetection, suboptimal structures are commonly suggestedfor use in iterative multiuser decoders. The use of suboptimalcomponents in the iterative structure leads to performance lossesin terms of system load, bit error rate (BER), and convergencespeed. In this paper, we introduce a simple recursive filteringstructure into the iterative multiuser decoder, aimed at improvingthe performance. Optimal filter coefficients are determined basedon the joint likelihood function of the correlated output loglikelihoodratios (LLRs) over iterations. Numerical results showthat iterative multiuser systems with recursive LLR filteringand a posteriori feedback at the single-user decoder stage canachieve superior BER performance, produce convergence infewer iterations, and accommodate an increasing number ofactive users.

  • 110.
    Nemeth, Peter S. A.
    et al.
    Chalmers University of Technology.
    Rasmussen, Lars Kildehöj
    Chalmers University of Technology.
    Aulin, Tor M.
    Chalmers University of Technology.
    Maximum-likelihood detection of block coded CDMA using the A* algorithm2001Inngår i: IEEE International Symposium on Information Theory, 2001, s. 88-88Konferansepaper (Fagfellevurdert)
  • 111. Nguyen, K. D.
    et al.
    Kildehöj Rasmussen, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Guillén i Fàbregas, A.
    Letzepis, N.
    MIMO ARQ with multibit feedback: Outage analysis2012Inngår i: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 58, nr 2, s. 765-779Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper studies the asymptotic outage performance of incremental redundancy automatic-repeat-request (INR-ARQ) transmission over multiple-input multiple-output (MIMO) block-fading channels with discrete input constellations. We first show that transmission with random codes using a discrete signal constellation across all transmit antennas achieves the optimal outage diversity given by the Singleton bound. The optimal SNR-exponent and outage diversity of INR-ARQ transmission over the MIMO block-fading channel are then analysed. We show that a significant gain in outage diversity is obtained by providing more than one bit feedback at each ARQ round. Thus, the outage performance of INR-ARQ transmission can be remarkably improved with minimal additional overhead. A practical feedback-and-power-adaptation rule is proposed for MIMO INR-ARQ, demonstrating the benefits provided by multibit feedback. Although the rule is sub-optimal in terms of outage performance, it achieves the optimal outage diversity.

  • 112. Nguyen, K. D.
    et al.
    Rasmussen, Lars K.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Delay-exponent of decode-forward streaming2013Inngår i: IEEE International Symposium on Information Theory: Proceedings, 2013, s. 2805-2809Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose a decode-forward protocol for streaming over a relay network using sequential random tree codes. An achievable bound on the end-to-end error performance is derived. The bound is parameterised by the number of errors occuring at the relay, which is the sum of correlated Bernoulli processes. The bound is useful for determining the achievable delay-exponent as well as for designing finite-delay relaying schemes. For a wide range of conjectured correlation models, the proposed scheme can achieve the delay-exponent of full source-relay cooperation.

  • 113. Nguyen, K. D.
    et al.
    Timo, R.
    Rasmussen, Lars K.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Causal-CSIT rate adaptation for block-fading channels2015Inngår i: IEEE International Symposium on Information Theory - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 351-355Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose a rate-adaptive error-correction coding framework for transmission over finite-length block-fading channels, with causal channel state information at the transmitter. A dynamic programming optimization approach can be use to obtain the optimal rate adaptation strategy. A suboptimal rate adaptation strategy is developed for sequential random codes. Numerical results show that significant performance gains are achievable with the proposed adaptation scheme. © 2015 IEEE.

  • 114.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Guillen i Fabregas, Albert
    University of Cambridge.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    A tight lower bound to the outage probability of discrete-input block-fading channels2007Inngår i: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 53, nr 11, s. 4314-4322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this correspondence, a tight lower hound to the outage probability of discrete-input Nakagami-m block-fading channels is proposed. The approach permits an efficient method for numerical evaluation of the bound, providing an additional tool for system design. The optimal rate-diversity tradeoff for the Nakagami-m, block-fading channel is also derived and a tight upper bound is obtained for the optimal coding gain constant.

  • 115.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Guillen i Fabregas, Albert
    University of Cambridge.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    Analysis and computation of the outage probability of discrete-input block-fading channels2007Inngår i: 2007 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY PROCEEDINGS, VOLS 1-7, 2007, s. 1196-1200Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    THIS PAPER IS ELIGIBLE FOR THE STUDENT PAPER AWARD. In this paper, we propose a tight lower bound to the outage probability of Nakagami-m block-fading channels. The approach permits an efficient method for numerical evaluation of the bound, providing an additional tool for system design. The optimal rate-diversity trade-off for the Nakagami-m block-fading channel is also derived and a tight upper bound is obtained for the optimal coding gain constant.

  • 116.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Guillen i Fabregas, Albert
    University of Cambridge.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    Asymptotic Outage Performance of Power Allocation in Block-Fading Channels2008Inngår i: 2008 IEEE International Symposium on Information Theory - Proceedings, New York: IEEE , 2008, s. 275-279Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We characterize the asymptotic outage performance of power allocation techniques for systems with average power constraints. We show that the outage diversity of a system with average power constraints can be obtained from the diversity of the corresponding system with peak power constraints. The characterization is therefore useful since the asymptotic performance of systems with peak power constraints is well known in the literature.

  • 117.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Guillen i Fabregas, Albert
    University of Cambridge.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Outage Exponents of Block-Fading Channels With Power Allocation2010Inngår i: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 56, nr 5, s. 2373-2381Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Power allocation is studied for fixed-rate transmission over block-fading channels with arbitrary continuous fading distributions and perfect transmitter and receiver channel state information. Both short-and long-term power constraints for arbitrary input distributions are considered. Optimal power allocation schemes are shown to be direct applications of previous results in the literature. It is shown that the short-and long-term outage exponents for arbitrary input distributions are related through a simple formula. The formula is useful to predict when the delay-limited capacity is positive. Furthermore, this characterization is useful for the design of efficient coding schemes for this relevant channel model.

  • 118.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Guillen i Fabregas, Albert
    University of Cambridge.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Power Allocation for Block-Fading Channels with Arbitrary Input Constellations2009Inngår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 8, nr 5, s. 2514-2523Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider power allocation strategies for arbitrary input channels with peak, average and peak-to-average power ratio (PAPR) constraints. We are focusing on systems with a fixed and finite input constellation, as encountered in most practical systems. Generalizing previous results, we derive the optimal power allocation scheme that minimizes the outage probability of block-fading channels with arbitrary input constellations, subject to PAPR constraints. We further show that the signal-to-noise ratio exponent for any finite peak-to-average power ratio is the same as that of the peak-power limited problem, resulting in an error floor. We also derive the optimal power allocation strategies that maximize the ergodic capacity for arbitrary input channels, subject to average and PAPR constraints. We show that capacities with peak-to-average power ratio constraints, even for small ratios, are close to capacities without peak-power restrictions. For both delay-limited and ergodic block-fading channels, the optimal power allocation strategies rely on the first derivative of the input-output mutual information, which may be computationally prohibitive for efficient practical implementation. To overcome this limitation, we develop suboptimal power allocation schemes that resemble the traditional water-filling technique. The suboptimal power allocation schemes significantly reduce computational and storage requirements, while enjoying minimal performance losses as compared to optimal schemes.

  • 119.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Guillen i Fabregas, Albert
    University of Cambridge.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    Power allocation for discrete-input non-ergodic block-fading channels2007Inngår i: 2007 IEEE INFORMATION THEORY WORKSHOP, VOLS 1 AND 2, 2007, s. 48-53Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We consider power allocation algorithms for fixed-rate transmission over Nakagami-m non-ergodic block-fading channels with perfect transmitter and receiver channel state information and discrete input signal constellations under short-and long-term power constraints. Optimal power allocation schemes are shown to be direct applications of previous results in the literature. We show that the SNR exponent of the optimal short-term scheme is given by the Singleton bound. We also illustrate the significant gains available by employing long-term power constraints. Due to the nature of the expressions involved, the complexity of optimal schemes may be prohibitive for system implementation. We propose simple sub-optimal power allocation schemes whose outage probability performance is very close to the minimum outage probability obtained by optimal schemes.

  • 120.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Guillen i Fabregas, Albert
    University of Cambridge.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    Power Control for Block-Fading Channels with Peak-to-Average Power Constraints2008Inngår i: Information Theory, 2008. ISIT 2008. IEEE International Symposium on, IEEE , 2008, s. 265-269Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Power allocation with peak-to-average power constraints over Nakagami-m block-fading channels with arbitrary input distributions is studied. In particular, we find the solution to the minimum outage power allocation scheme with peak-to-average power constraints and arbitrary input distributions, and show that the signal-to-noise ratio exponent for any systems with a finite peak-to-average power ratio constraint is the same as that of systems with peak-power constraints, resulting in an error floor.

  • 121.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Letzepis, Nick
    University of South Australia.
    Guillen i Fabregas, Albert
    University of Cambridge.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Outage Diversity of MIMO Block-Fading Channels with Causal Channel State Information2010Inngår i: IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, 2010, s. 2168-2172Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We study the outage diversity of the multiple-input multiple-output (MIMO) Rayleigh block-fading channel when causal channel state information (CSI) is available at the transmitter (CSIT). Within this setting, we consider the optimal power allocation for blocks b = 1,..., B given perfect CSIT for blocks 1,..., b - u only, subject to a long-term power constraint. The parameter 0 <= u <= B is a fixed arbitrary integer that determines the delay in acquiring perfect knowledge of the CSI at the transmitter. Without explicitly solving the optimal power allocation problem, we derive the outage diversity of the system. For general 0 <= u <= B, we derive a simple recursive expression for computing the outage diversity. For the special case u = 0, it is shown that the outage diversity is infinite, coinciding with previously known results. For 1 <= u <= = B, the outage diversity becomes finite and for the special case of u = 1, 2 it can be expressed in simple closed form.

  • 122.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Delay-universal decode-and-forward relaying2011Inngår i: Proceedings of the 2011 Australian Communications Theory Workshop, AusCTW 2011, 2011, s. 170-175Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We study delay-universal sequential streaming over discrete memoryless three-terminal relay networks, and propose a decode-and-forward relaying scheme. We derive upper bounds on the error performance of the proposed system, which assists in system design and analysis. The bounds also show that the proposed relaying scheme, and decode-and-forward relaying in general, can achieve the optimal delay exponent under certain channel conditions.

  • 123.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Guillen i Fabregas, Albert
    University of Cambridge.
    Letzepis, Nick
    University of South Australia.
    MIMO ARQ Systems with Multi-Level Feedback2009Inngår i: 2009 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, VOLS 1- 4, 2009, s. 254-258Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider improving the outage performance of incremental-redundancy automatic repeat request (INR-ARQ) transmission over the multiple-input multiple-output (MIMO) block-fading channel by allowing multi-bit receiver feedback. We show that multi-bit feedback offers significant gain in outage diversity when power adaptation is employed. A suboptimal feedback and power adaptation rule is proposed, illustrating the benefits provided by multi-bit feedback.

  • 124.
    Nguyen, Khoa D.
    et al.
    University of South Australia.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Guillen i Fabregas, Albert
    University of Cambridge.
    Letzepis, Nick
    University of South Australia.
    Rate-Diversity-Delay Tradeoff for ARQ Systems over MIMO Block-Fading Channels2009Inngår i: Proceedings of the 2009 Australian Communications Theory Workshop, AusCTW 2009, IEEE , 2009, s. 116-121Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We study the effect of power adaptation on the outage diversity of Incremental-redundancy automatic-repeat-request (INR-ARQ) transmission over the multi-input multi-output (MIMO) block-fading channel. In particular, we derive the optimal outage diversity achieved by power adaptation in INR-ARQ systems, and show that power adaptation provides significant gains in outage diversity. We also prove that the optimal outage diversity is achievable with random coding schemes.

  • 125.
    Ping, He
    et al.
    National University of Singapore.
    Tjhung, T T
    National University of Singapore.
    Rasmussen, Lars Kildehöj
    National University of Singapore.
    Decision-feedback blind adaptive multiuser detector for synchronous CDMA system2000Inngår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 49, nr 1, s. 159-166Artikkel i tidsskrift (Fagfellevurdert)
  • 126.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    A constrained optimization approach to nonlinear interference cancellation2011Inngår i: IEEE Swedish Communication Technologies Workshop (Swe-CTW), 2011, s. 52-57Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Nonlinear interference cancellation has been successful as a low-complexity iterative detection strategy for multiple-input, multiple-output channels. However, such strategies are generally difficult to analyze. Here we develop a connection to constrained optimization through the use of penalty functions. The resulting framework provides a means of analysis, and includes known nonlinear cancellation schemes.

  • 127.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    Iterative detection methods for multi-user direct sequence CDMA systems2003Inngår i: The Wiley Encyclopedia of Telecommunications / [ed] John Proakis, Online: John Wiley & Sons, 2003Kapittel i bok, del av antologi (Fagfellevurdert)
  • 128.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    Linear detection in iterative joint multiuser decoding2008Inngår i: INTERNATIONAL SYMPOSIUM ON COMMUNICATIONS, CONTROL AND SIGNAL PROCESSING, 2008, s. 753-757Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we provide a tutorial-style overview of linear detection in iterative joint multiuser decoding. We show that a generic linear iterative joint multiuser decoder naturally replaces the canonical iterative joint multiuser decoder. The generic linear structure is particularly well-suited for interference cancellation and LMMSE filtering with priors, which incidently is interference cancellation followed by per-user instantaneous LMMSE filtering. A controversial issue for linear iterative joint multiuser decoding is the type of information feedback to the multiuser detector. Here we present numerical results for both the exchange of extrinsic and posterior information and conclude that in terms of spectral efficiency there are only small differences.

  • 129.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    Multiuser detection and antenna arrays: (Chapter 5)2000Inngår i: Space-Time Processing for CDMA Mobile Communications / [ed] Pieter van Rooyen, Michel Lötter, and Danie van Wyk, Kluwer Academic Publishers, 2000, 1Kapittel i bok, del av antologi (Fagfellevurdert)
  • 130.
    Rasmussen, Lars Kildehöj
    Chalmers University of Technology.
    On ping-pong effects in linear interference cancellation for CDMA2000Inngår i: IEEE Sixth International Symposium on Spread Spectrum Techniques and Applications, 2000, s. 348-352Konferansepaper (Fagfellevurdert)
  • 131.
    Rasmussen, Lars Kildehöj
    et al.
    University of South Australia.
    Grant, Alex J.
    University of South Australia.
    Alexander, Paul D.
    University of South Australia.
    An extrinsic Kalman filter for iterative multiuser decoding2004Inngår i: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 50, nr 4, s. 642-648Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One powerful approach for multiuser decoding is to iterate between a linear multiuser filter (which ignores coding constraints) and individual decoders (which ignore multiple-access interference). Subject to clearly formulated statistical assumptions and the history of input signals provided by the outer decoders over all previous iterations, an extrinsic Kalman filter is suggested. This approach is motivated by the recent observation that decoder outputs are loosely correlated during initial iterations. Numerical results show that iterative decoding using this filter provides better performance in terms of the supportable load and convergence speed as compared to previously suggested linear-filter-based iterative decoders.

  • 132.
    Rasmussen, Lars Kildehöj
    et al.
    University of South Australia.
    Grant, Alex J.
    University of South Australia.
    Alexander, Paul D.
    University of South Australia.
    Recursive Bayesian filtering for iterative multiuser decoding2003Inngår i: 3rd International Symposium on Turbo Codes & Related Topics, 2003, s. 187-190Konferansepaper (Fagfellevurdert)
  • 133.
    Rasmussen, Lars Kildehöj
    et al.
    University of South Australia.
    Grant, Alex J.
    University of South Australia.
    Alexander, Paul D.
    University of South Australia.
    Recursive filters for iterative multiuser decoding2002Inngår i: IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, 2002, s. 445-445Konferansepaper (Annet vitenskapelig)
  • 134.
    Rasmussen, Lars Kildehöj
    et al.
    National University of Singapore.
    Lim, Teng Joon
    National University of Singapore.
    Aulin, Tor M.
    Chalmers University of Technology.
    Breadth-first maximum likelihood detection in multiuser CDMA1997Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 45, nr 10, s. 1176-1178Artikkel i tidsskrift (Fagfellevurdert)
  • 135.
    Rasmussen, Lars Kildehöj
    et al.
    National University of Singapore.
    Lim, Teng Joon
    National University of Singapore.
    Johansson, Ann-Louise
    Chalmers University of Technology.
    A matrix-algebraic approach to successive interference cancellation in CDMA2000Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 48, nr 1, s. 145-151Artikkel i tidsskrift (Fagfellevurdert)
  • 136.
    Rasmussen, Lars Kildehöj
    et al.
    Chalmers University of Technology.
    Oppermann, Ian
    Convergence behaviour of linear parallel cancellation in CDMA2001Inngår i: IEEE Global Telecommunications Conference, 2001, s. 3148-3152Konferansepaper (Fagfellevurdert)
  • 137.
    Rasmussen, Lars Kildehöj
    et al.
    University of South Australia.
    Oppermann, Ian J.
    Southern Poro Communications, Australia.
    Ping-pong effects in linear parallel interference cancellation for CDMA2003Inngår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 2, nr 2, s. 357-363Artikkel i tidsskrift (Fagfellevurdert)
  • 138.
    Rasmussen, Lars Kildehöj
    et al.
    University of South Australia.
    Tan, Peng Hui
    Chalmers University of Technology.
    Recursive interference cancellation based on simplified belief propagation2008Inngår i: 2008 AUSTRALIAN COMMUNICATIONS THEORY WORKSHOP, 2008, s. 45-50Konferansepaper (Fagfellevurdert)
    Abstract [en]

    For practical implementation of multiuser detection, interference cancellation schemes of minimal complexity are almost exclusively of interest. In this paper, we derive a recursive cancellation scheme based on simplified belief propagation. The simplifications follow from Gaussian and large-system approximations, and lead to a structure of the same order of complexity as simple parallel cancellation. The resulting scheme can be interpreted as a recursive update of a noise hypothesis, filtered across iterations. The performance of the proposed detector is compared to competing cancellation schemes of the same order of complexity, and improvements are observed for larger system loads.

  • 139.
    Rasmussen, Lars Kildehöj
    et al.
    University of South Australia.
    Uhlemann, Elisabeth
    Halmstad University.
    Brännström, Fredrik
    Chalmers University of Technology.
    Concatenated systems and cross-layer design2006Inngår i: 7th Australian Communications Theory Workshop 2006, Proceedings, 2006, s. 80-86Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With high data rate wireless communications networks, new applications relying on high quality audio, video or control become viable. Examples of such applications are remote tele-medicine, collision avoidance systems, and audio/video entertainment at CD/DVD quality. These applications all demand high data rates, but have different quality-of-service (QGS) requirements in terms of reliability and latency. Currently, mobile communications networks have only limited provisions for QoS implementation and control. The conventional functionality separation in network design may be inhibiting effective implementation of guaranteed QoS. In this paper, we propose and review a system design paradigm based on concatenated system models and iterative signal processing. The novelty of the paradigm is to propagate methodologies of physical layer design across disciplinary boundaries within wireless network design in a bottom-up cross-layer approach. The paper is tutorial in nature, promoting the new view through presenting a series of examples of successful application of concatenated systems design from the physical and link layers. The purpose of the paper is to inspire new research directions.

  • 140.
    Rasmussen, Lars Kildehöj
    et al.
    Georgia Institute of Technology.
    Wicker, Stephen B.
    Georgia Institute of Technology.
    A COMPARISON OF 2 COMBINING TECHNIQUES FOR EQUAL GAIN, TRELLIS-CODED DIVERSITY RECEIVERS1995Inngår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 44, nr 2, s. 291-295Artikkel i tidsskrift (Fagfellevurdert)
  • 141.
    Rasmussen, Lars Kildehöj
    et al.
    Georgia Institute of Technology.
    Wicker, Stephen B.
    Georgia Institute of Technology.
    COMPARISON OF 2 RETRANSMISSION REQUEST MECHANISMS FOR TRELLIS-CODED MODULATION1993Inngår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 29, nr 25, s. 2162-2163Artikkel i tidsskrift (Fagfellevurdert)
  • 142.
    Rasmussen, Lars Kildehöj
    et al.
    Georgia Institute of Technology.
    Wicker, Stephen B.
    Georgia Institute of Technology.
    TRELLIS-CODED, TYPE-I HYBRID-ARQ PROTOCOLS BASED ON CRC ERROR-DETECTING CODES1995Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 43, nr 10, s. 2569-2575Artikkel i tidsskrift (Fagfellevurdert)
  • 143.
    Rasmussen, Lars Kildehöj
    et al.
    Georgia Institute of Technology.
    Wicker, Stephen D.
    Georgia Institute of Technology.
    THE PERFORMANCE OF TYPE-I TRELLIS-CODED HYBRID-ARQ PROTOCOLS OVER AWGN AND SLOWLY FADING CHANNELS1994Inngår i: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 40, nr 2, s. 418-428Artikkel i tidsskrift (Fagfellevurdert)
  • 144.
    Rathi, Vishwambhar
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Aurell, Erik
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsbiologi, CB. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Bounds on Threshold of Regular Random k-SAT2010Inngår i: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 6175, s. 264-277Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider the regular model of formula generation in conjunctive normal form (CNF) introduced by Boufkhad et. al. in [6]. In [6], it was shown that the threshold for regular random 2-SAT is equal to unity. Also, upper and lower bound on the threshold for regular random 3-SAT were derived. Using the first moment method, we derive an upper bound on the threshold for regular random k-SAT for any k >= 3 and show that for large k the threshold is upper bounded by 2(k) ln(2). We also derive upper bounds on the threshold for Not-All-Equal (NAE) satisfiability for k >= 3 and show that for large k, the NAE-satisfiability threshold is upper bounded by 2(k-1) ln(2). For both satisfiability and NAE-satisfiability, the obtained upper bound matches with the corresponding bound for the uniform model of formula generation [9, 1]. For the uniform model, in a series of break through papers Achlioptas, Moore, and Peres showed that a careful application of the second moment method yields a significantly better lower bound on threshold as compared to any rigorously proven algorithmic bound [3, I]. The second moment method shows the existence of a satisfying assignment with uniform positive probability (w.u.p.p.). Thanks to the result of Friedgut for uniform model [ 1 0], existence of a satisfying assignment w.u.p.p. translates to existence of a satisfying assignment with high probability (w.h.p.). Thus, the second moment method gives a lower bound on the threshold. As there is no known Friedgut type result for regular random model, we assume that for regular random model existence of a satisfying assignments w.u.p.p. translates to existence of a satisfying assignments w.h.p. We derive the second moment of the number of satisfying assignments for regular random k-SAT for k >= 3. There are two aspects in deriving the lower bound using the second moment method. The first aspect is given any k, numerically evaluate the lower bound on the threshold. The second aspect is to derive the lower bound as a function of k for large enough k. We address the first aspect and evaluate the lower bound on threshold. The numerical evaluation suggests that as k increases the obtained lower bound on the satisfiability threshold of a regular random formula converges to the lower bound obtained for the uniform model. Similarly, we obtain lower bounds on the NAE-satisfiability threshold of the regular random formulas and observe that the obtained lower bound seems to converge to the corresponding lower bound for the uniform model as k increases.

  • 145.
    Rathi, Vishwambhar
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Aurell, Erik
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsbiologi, CB.
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Bounds on thresholds related to maximum satisfiability of regular random formulas2010Inngår i: 6th International Symposium on Turbo Codes and Iterative Information Processing (ISTC), 2010, s. 107-111Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider the regular balanced model of satisfiability formula generation in conjunctive normal form (CNF), where each literal participates in equal number of clauses and there are k literals participating in a clause. We say that a formula is p-satisfying if there is a truth assignment satisfying 1 - 2-k + p2- fraction of clauses. Using the first moment method we determine upper bound on the threshold clause density such that there are no p-satisfying assignments with high probability above this upper bound. There are two aspects in deriving the lower bound using the second moment method. The first aspect is, given any p ∈ (0,1) and k, evaluate the lower bound on the threshold. This evaluation is numerical in nature. The second aspect is to derive the lower bound as a function of p for large enough k. We address the first aspect and evaluate the lower bound on the p-satisfying threshold using the second moment method. Based on the numerical evaluation, we observe that as k increases the ratio of the lower bound and the upper bound seems to converge to one.

  • 146.
    Schrammar, Nicolas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Farhadi, Hamed
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars K.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Average Throughput in AWGN Cognitive Fading Interference Channel with Multiple Secondary Pairs2012Inngår i: Proceedings of the 2012 7th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCOM 2012, IEEE Computer Society, 2012, s. 158-162Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider the additive white Gaussian noise (AWGN) cognitive fading interference channel consisting of one primary and multiple secondary transmitter-receiver pairs. The secondary transmitters have non-causal knowledge of the primary message. We find a tuple of achievable rates by utilizing the discrete superposition model (DSM), which is a simplified, deterministic channel model. The coding scheme devised for the DSM can be translated into a coding scheme for the AWGN model, where the rate achieved in the AWGN model is at most a constant gap below the rate achieved in the DSM. We then calculate the average throughput of the secondary pairs under the assumption of Rayleigh fading channels. The main result is that our scheme performs well in the weak interference regime. The sum-throughput increases with the number of secondary pairs.

  • 147.
    Schrammar, Nicolas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Wang, Chao
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars Kildehøj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    New Achievable Rates for Gaussian Partially Cognitive Interference Channels With Multiple Cognitive Pairs2014Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 62, nr 6, s. 2051-2060Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper characterizes achievable rate regions for the Gaussian partially cognitive interference channel with multiple cognitive pairs (K-PCIFC), where the cognitive transmitters know one part of the primary transmitter's message. We explore a novel methodology using the deterministic discrete superposition model (DSM). We find codes and their achievable rate regions in the DSM, and we show that they yield achievable rate regions in the Gaussian model. Our coding scheme in the DSM can be applied in general scenarios. We devise an achievable rate region for the K-PCIFC, which is within a constant gap to known outer bounds for K = 2 in the weak interference regime. From our expressions we derive guidelines for designing the cognitive link between the primary transmitter and the cognitive transmitters. Furthermore, we show that the gain from cognition diminishes for increasing K.

  • 148.
    Schrammar, Nicolas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Wang, Chao
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars K.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    On the Discrete Superposition Model of Partially Cognitive Interference Channels2012Inngår i: 2012 Conference Record Of The Forty Sixth Asilomar Conference On Signals, Systems And Computers (Asilomar), IEEE Computer Society, 2012, s. 1813-1817Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We find an achievable rate region for the partially cognitive interference channel in the weak interference regime, where the cognitive transmitter learns the primary message over a noiseless link with finite capacity. The rate region is established in the discrete superposition model, which has the property of approximating the AWGN model within a constant gap. In the high SNR regime our region is close to known outer bounds on the AWGN capacity region, yet its formulation is sufficiently simple to give valuable insights. Interestingly, the cognitive transmitter does not need to learn the complete primary message in order to achieve the rate region of the fully cognitive interference channel. The capacity of the noiseless link between the two transmitters is sufficiently large if it equals the single-user capacity of the cross-link from primary transmitter to secondary receiver.

  • 149.
    Stathakis, Efthymios
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Jalden, Joakim
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Rasmussen, Lars K.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Outage Region Characterization for Beamforming in MISO Interference Networks with Imperfect CSI2015Inngår i: IEEE Signal Processing Letters, ISSN 1070-9908, E-ISSN 1558-2361, Vol. 22, nr 12, s. 2378-2382, artikkel-id 7286738Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider an interference network with independent links, whose multi-Antenna transmitters have access to an imperfect analog estimate of their local channels. Assuming that the receivers treat the interference as noise, we define the outage rate region as the set of rate-Tuples that are achievable with a given probability and we characterize the boundary of the region for transmit beamforming. Our study shows that the Pareto-optimal beamforming vectors judiciously balance the desired signal power and the interference power based on the quality of the estimated channel state. Our analysis further reveals that, in contrast to the well-known results by Jorswieck , for the perfect channel side-information case, transmission at full power is not necessarily Pareto-optimal.

  • 150.
    Stathakis, Efthymios
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Joakim, Jaldén
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars K.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Uniformly Improving Maximum-Likelihood SNR Estimation of Known Signals in Gaussian Channels2014Inngår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 62, nr 1, s. 156-167Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The signal-to-noise ratio (SNR) estimation problem is considered for an amplitude modulated known signal in Gaussian noise. The benchmark method is the maximum-likelihood estimator (MLE), whose merits are well-documented in the literature. In this work, an affinely modified version of the MLE (AMMLE) that uniformly outperforms, over all SNR values, the traditional MLE in terms of the mean-square error (MSE) is obtained in closed-form. However, construction of an AMMLE whose MSE is lower, at every SNR, than the unbiased Cramer-Rao bound (UCRB), is shown to be infeasible. In light of this result, the AMMLE construction rule is modified to provision for an a priori known set, where the SNR lies, and the MSE enhancement target is pursued within. The latter is realized through proper extension of an existing framework, due to Eldar, which settles the design problem by solving a semidefinite program. The analysis is further extended to the general case of vector signal models. Numerical results show that the proposed design demonstrates enhancement of the MSE for all the considered cases.

12345 101 - 150 of 201
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf