Analysis of Channel-Averaged SINR for Indoor UWB Rake and Transmitted Reference Systems

s of Forthcoming Manuscripts Analysis of Channel-Averaged SINR for Indoor UWB Rake and Transmitted Reference Systems Tao Jia and Dong In Kim Abstract—In this paper, we derive a closed-form expression for channelaveraged signal-to-interference-plus-noise ratio for ultrawideband (UWB) Rake receiving system in an indoor multiuser communication scenario, given that the interference level is fluctuating due to asynchronous transmissions among the users. The indoor wireless channel model adopted here is a standard one recently released by IEEE 802.15 Study Group 3a. We propose a theoretical framework to derive the channel-averaged SINR, considering the lognormal channel gain distribution and the double independent Poisson arrival distribution of cluster and ray, and show that our analysis is well coincident with the simulation results. With this framework, we demonstrate that our analysis can be applied to theoretically determine the optimum integration interval for a UWB transmitted reference system, even in a multiuser scenario.In this paper, we derive a closed-form expression for channelaveraged signal-to-interference-plus-noise ratio for ultrawideband (UWB) Rake receiving system in an indoor multiuser communication scenario, given that the interference level is fluctuating due to asynchronous transmissions among the users. The indoor wireless channel model adopted here is a standard one recently released by IEEE 802.15 Study Group 3a. We propose a theoretical framework to derive the channel-averaged SINR, considering the lognormal channel gain distribution and the double independent Poisson arrival distribution of cluster and ray, and show that our analysis is well coincident with the simulation results. With this framework, we demonstrate that our analysis can be applied to theoretically determine the optimum integration interval for a UWB transmitted reference system, even in a multiuser scenario. T. Jia is with the Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA 24061-0111 USA. D. I. Kim is with the School of Information and Communication Engineering, Sungkyunkwan University, Suwon 440746, Korea. Digital Object Identifier 10.1109/TCOMM.2007.904350 Capacity Approaching Turbo Coding For Half-Duplex Relaying Zheng Zhang and Tolga M. Duman Abstract—In this paper, we develop capacity approaching turbo coding schemes for half-duplex relay systems as an extension of our previous work on coding for full-duplex relays. We consider the use of specific signal constellations (e.g., binary phase-shift keying) in transmission, develop practical coding schemes to be used at the source and the relay nodes, and describe a suitable information combining technique at the destination node. Unlike the full-duplex relay systems, the destination node does not perform joint decoding of multiple consecutive blocks; instead, it works with one frame at a time. Furthermore, for the half-duplex relaying scheme, the optimization of the length of the listening period for the relay node is an issue. By utilizing the information theoretical tools, we perform this optimization, and use it in our development of capacity approaching coding/decoding schemes. Specifically, when the fraction of time turns out to be less than the transmission rate, the relay node is unable to decode all the information bits transmitted, and a partial decoding approach has to be used. Through a comprehensive set of examples, we observe that the proposed scheme is promising to approach the corresponding information theoretical limits (bounds). In particular, for all the cases studied, we have obtained bit error rates of 10−5 or lower within 1–1.5 dB (in most cases, around within 1.2 dB) of the constrained capacity under a variety of channel conditions. Extensions of the proposed scheme to coded modulation and to multiple-input multiple-output systems are also described.In this paper, we develop capacity approaching turbo coding schemes for half-duplex relay systems as an extension of our previous work on coding for full-duplex relays. We consider the use of specific signal constellations (e.g., binary phase-shift keying) in transmission, develop practical coding schemes to be used at the source and the relay nodes, and describe a suitable information combining technique at the destination node. Unlike the full-duplex relay systems, the destination node does not perform joint decoding of multiple consecutive blocks; instead, it works with one frame at a time. Furthermore, for the half-duplex relaying scheme, the optimization of the length of the listening period for the relay node is an issue. By utilizing the information theoretical tools, we perform this optimization, and use it in our development of capacity approaching coding/decoding schemes. Specifically, when the fraction of time turns out to be less than the transmission rate, the relay node is unable to decode all the information bits transmitted, and a partial decoding approach has to be used. Through a comprehensive set of examples, we observe that the proposed scheme is promising to approach the corresponding information theoretical limits (bounds). In particular, for all the cases studied, we have obtained bit error rates of 10−5 or lower within 1–1.5 dB (in most cases, around within 1.2 dB) of the constrained capacity under a variety of channel conditions. Extensions of the proposed scheme to coded modulation and to multiple-input multiple-output systems are also described. The authors are with the Electrical Engineering Department, Arizona State University, Tempe, AZ 85287-9309 USA. Digital Object Identifier 10.1109/TCOMM.2007.904347 Generalized Quadratic Receivers for Unitary Space–Time Modulation Over Rayleigh Fading Channels Rong Li and Pooi Yuen Kam Abstract—We propose the generalized quadratic receivers (GQRs) for unitary space–time modulation over flat Rayleigh fading channels. The GQRs realize the performance improvement potential, known to be approximately 2–4 dB, between the quadratic receiver (QR) and the coherent receiver (CR), by performing channel estimation without the help of additional training signals that consume additional bandwidth. They are designed for various unitary space–time constellations (USTC) in which signal matrices may or may not contain explicit inherent training blocks, and may be orthogonal or nonorthogonal to one another. As the channel memory span exploited for channel estimation increases, the error probability of the GQRs reduces from that of the QR to that of the CR. The GQRs work well for both slow and fast fading channels, and the performance improvement increases as the channel fade rate decreases. For a class of USTC with the orthogonal design structure, the GQR is simplified to a form whose complexity can be less than the complexity of the QR or even that of the simplified form of the QR.We propose the generalized quadratic receivers (GQRs) for unitary space–time modulation over flat Rayleigh fading channels. The GQRs realize the performance improvement potential, known to be approximately 2–4 dB, between the quadratic receiver (QR) and the coherent receiver (CR), by performing channel estimation without the help of additional training signals that consume additional bandwidth. They are designed for various unitary space–time constellations (USTC) in which signal matrices may or may not contain explicit inherent training blocks, and may be orthogonal or nonorthogonal to one another. As the channel memory span exploited for channel estimation increases, the error probability of the GQRs reduces from that of the QR to that of the CR. The GQRs work well for both slow and fast fading channels, and the performance improvement increases as the channel fade rate decreases. For a class of USTC with the orthogonal design structure, the GQR is simplified to a form whose complexity can be less than the complexity of the QR or even that of the simplified form of the QR. The authors are with the Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576. Digital Object Identifier 10.1109/TCOMM.2007.904351 Approximation for a Sum of On-Off Log-Normal Processes With Wireless Applications C. Fischione, F. Graziosi, and F. Santucci Abstract—In this paper, a log-normal approximation is proposed for the sum of log-normal processes weighted by binary processes. The analytical approach moves from the method earlier proposed by Wilkinson for approximating first-order statistics of the sum of log-normal components, and extends to incorporate second-order statistics and the presence of both time-correlated random binary weights and cross-correlated log-normal components in moments’ matching. Since the sum of weighted log-normal processes models the signal-to-interference-plus-noise ratio of wireless systems, the method can be applied to evaluate in an effective and accurate way the outage occurrence rate and outage duration for different wireless systems of practical interest. In a frequency-reuse-based cellular system, the method is applied to various propagation scenarios, characterized by different shadowing correlation decay distances and correlations among shadowing components. A further case of relevant interest is related to power-controlled wideband wireless systems, where the random weights are binary random variables denoting the activity status of each interfering source. Finally, simulation results are used to confirm the validity of the analysis for the considered cases of practical interest.In this paper, a log-normal approximation is proposed for the sum of log-normal processes weighted by binary processes. The analytical approach moves from the method earlier proposed by Wilkinson for approximating first-order statistics of the sum of log-normal components, and extends to incorporate second-order statistics and the presence of both time-correlated random binary weights and cross-corr