The Experts below are selected from a list of 5583 Experts worldwide ranked by ideXlab platform
T H Meng - One of the best experts on this subject based on the ideXlab platform.
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iterative power control for imperfect Successive Interference Cancellation
IEEE Transactions on Wireless Communications, 2005Co-Authors: A. Agrawal, Jeffrey G Andrews, J M Cioffi, T H MengAbstract:Successive Interference Cancellation (SIC) is a technique for increasing the capacity of cellular code-division multiple-access (CDMA) systems. To be successful, SIC systems require a specific distribution of the users' received powers, especially in the inevitable event of imperfect Interference Cancellation. This apparent complication of standard CDMA power control has been frequently cited as a major drawback of SIC. In this paper, it is shown that surprisingly, these "complications" come with no additional complexity. It is shown that 1-bit UP/DOWN power control-like that used in commercial systems-monotonically converges to the optimal power distribution for SIC with Cancellation error. The convergence is proven to within a discrete step-size in both signal-to-noise plus Interference ratio and power. Additionally, the algorithm is applicable to multipath and fading channels and can overcome channel estimation error with a standard outer power control loop.
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performance of multicarrier cdma with Successive Interference Cancellation in a multipath fading channel
IEEE Transactions on Communications, 2004Co-Authors: Jeffrey G Andrews, T H MengAbstract:A high capacity, low complexity, and robust system design for a Successive Interference Cancellation (SIC) system is developed and analyzed. Multicarrier code-division multiple access (MC-CDMA) is used to suppress multipath and to overcome the multipath channel estimation problem in single-carrier SIC systems. In addition, an optimal power control algorithm for MC-CDMA with SIC is derived, allowing analytical bit-error rate expressions to be found for an uncoded system. Low-rate forward error-correcting codes are then added to the system to achieve robustness. It is found that the capacity of the coded system approaches the additive white Gaussian noise capacity for SIC, even in a fading multipath channel with channel estimation error. This indicates that MC-CDMA is very attractive for systems employing SIC.
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optimum power control for Successive Interference Cancellation with imperfect channel estimation
IEEE Transactions on Wireless Communications, 2003Co-Authors: J G Andrews, T H MengAbstract:Successive Interference Cancellation, in conjunction with orthogonal convolutional codes, has been shown to approach the Shannon capacity for an additive white Gaussian noise channel. However, this requires highly accurate estimates for the amplitude and phase of each user's signal. We derive an optimal power control strategy specifically designed to maximize the overall capacity under the constraint of a high degree of estimation error. This power control strategy presents a general formula of which other power control algorithms are special cases. Even with estimation error as high as 50%, capacity can be approximately doubled relative to not using Interference Cancellation. In addition, when properly applied to multicell mobile networks, this power control scheme can reduce the handset transmit power, and therefore other-cell Interference, by more than an order of magnitude.
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performance of multicarrier cdma with Successive Interference Cancellation with estimation error in a multipath fading channel
International Symposium on Spread Spectrum Techniques and Applications, 2002Co-Authors: J G Andrews, T H MengAbstract:A high-capacity, low-complexity, and robust system design for a Successive. Interference Cancellation (SIC) system is analyzed. Multicarrier CDMA (MC-CDMA) is used to suppress multipath and to overcome the multipath channel estimation problem in SIC systems. An optimal power control algorithm for MC-CDMA with SIC is derived, allowing analytical BER expressions to be found. It is shown that with coding, the capacity of the proposed system approaches the AWGN capacity for SIC even in a fading multipath channel with channel estimation error.
Georgios B Giannakis - One of the best experts on this subject based on the ideXlab platform.
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a robust high throughput tree algorithm using Successive Interference Cancellation
IEEE Transactions on Communications, 2007Co-Authors: Xin Wang, Georgios B GiannakisAbstract:A novel random access protocol combining a tree algorithm (TA) with Successive Interference Cancellation (SIC) has been introduced recently. To mitigate the deadlock problem of SICTA arising in error-prone wireless networks, we put forth a SICTA with first success (SICTA/FS) protocol, which is capable of high throughput while requiring limited-sensing and gaining robustness to errors relative to SICTA.
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high throughput random access using Successive Interference Cancellation in a tree algorithm
IEEE Transactions on Information Theory, 2007Co-Authors: Georgios B GiannakisAbstract:Random access is well motivated and has been widely applied when the network traffic is bursty and the expected throughput is not high. The main reason behind relatively low-throughput expectations is that collided packets are typically discarded. In this paper, we develop a novel protocol exploiting Successive Interference Cancellation (SIC) in a tree algorithm (TA), where collided packets are reserved for reuse. Our SICTA protocol can achieve markedly higher maximum stable throughput relative to existing alternatives. Throughput performance is analyzed for general d-ary SICTA with both gated and window access. It is shown that the throughput for d-ary SICTA with gated access is about (ln d)/(d - 1), and can reach 0.693 for d = 2. This represents a 40% increase over the renowned first-come-first-serve (FCFS) 0.487 tree algorithm. Delay performance is also analyzed for SICTA with gated access, and numerical results are provided.
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a robust high throughput tree algorithm using Successive Interference Cancellation
Global Communications Conference, 2005Co-Authors: Xin Wang, Georgios B GiannakisAbstract:A novel random access protocol combining a tree algorithm (TA) with Successive Interference Cancellation (SIC) has been introduced recently. By migrating physical layer benefits to the medium access control (MAC) through a cross-layer approach, SICTA can afford stable throughput as high as 0.693. However, SICTA may lead to deadlocks caused by channel fading and error propagation in error-prone wireless networks. To mitigate such effects, we put forth a truncated version of SICTA that we term SICTA/FS (SICTA with first success). We establish using analysis and simulations that while providing high throughput, SICTA/FS is robust to errors, it is easy to implement, and can be readily incorporated to existing standards
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sicta a 0 693 contention tree algorithm using Successive Interference Cancellation
International Conference on Computer Communications, 2005Co-Authors: Georgios B GiannakisAbstract:Contention tree algorithms have provable stability properties, and are known to achieve stable throughput as high as 0.487 for the infinite population Poisson model. A common feature in all these random access protocols is that collided packets at the receive-node are always discarded. In this paper, we derive a novel tree algorithm (TA) that we naturally term SICTA because it relies on Successive Interference Cancellation to resolve collided packets. Performance metrics including throughput and delay are analyzed to establish that SICTA outperforms existing contention tree algorithms reaching 0.693 in stable throughput.
J M Holtzman - One of the best experts on this subject based on the ideXlab platform.
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practical implementation of Successive Interference Cancellation in ds cdma systems
IEEE International Conference on Universal Personal Communications, 1996Co-Authors: K I Pedersen, T E Kolding, Ivan Seskar, J M HoltzmanAbstract:This paper addresses the practical implementation of Successive Interference Cancellation (SIC) for DS/CDMA systems. The practical aspects of such an implementation are discussed and an FPGA-based detector employing SIC are presented. An important aspect is the integration of power control and Interference Cancellation which has several benefits.
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effect of tracking error on ds cdma Successive Interference Cancellation
Global Communications Conference, 1994Co-Authors: Fangchen Cheng, J M HoltzmanAbstract:Since the optimal DS/CDMA multiuser detector is too complex, much work is being done in order to see whether a practical version is feasible. Among the issues that need to be addressed are departures from ideal assumptions that may affect the performance. The authors derive results for the performance degradation that a Successive Interference Cancellation scheme experiences due to synchronization tracking error. Results are displayed as a function of the synchronization tracking error, normalized to the chip duration. It is shown that the Interference canceller still retains a performance advantage over the conventional detector.
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ds cdma Successive Interference Cancellation
International Symposium on Spread Spectrum Techniques and Applications, 1994Co-Authors: J M HoltzmanAbstract:Conventional DS/CDMA detectors operate by enhancing a desired user while suppressing other users, considered as Interference (multiple access Interference, MAI) or noise. A different viewpoint is to consider other users not as noise but to jointly detect all users' signals (multiuser detection). This has significant potential of increasing capacity and near/far resistance. Optimal multiuser detection is, however, too complex to implement, thus motivating the search for suboptimal algorithms. Our objective is to underline the need for simplicity and to discuss what is a relatively simple form of multiuser detection (at the base station of a cellular system), Successive Interference Cancellation. The Cancellation scheme uses only components already present in a conventional detector. >
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analysis of a simple Successive Interference Cancellation scheme in a ds cdma system
IEEE Journal on Selected Areas in Communications, 1994Co-Authors: P Patel, J M HoltzmanAbstract:Compensating for near/far effects is critical for satisfactory performance of DS/CDMA systems. So far, practical systems have used power control to overcome fading and near/far effects. Another approach, which has a fundamental potential in not only eliminating near/far effects but also in substantially raising the capacity, is multiuser detection and Interference Cancellation. Various optimal and suboptimal schemes have been investigated. Most of these schemes, however, get too complex even for relatively simple systems and rely on good channel estimates. For Interference Cancellation, estimation of channel parameters (viz. received amplitude and phase) is important. We analyze a simple Successive Interference Cancellation scheme for coherent BPSK modulation, where the parameter estimation is done using the output of a linear correlator. We then extend the analysis for a noncoherent modulation scheme, namely M-ary orthogonal modulation. For the noncoherent case, the needed information on both the amplitude and phase is obtained from the correlator output. The performance of the IC scheme along with multipath diversity combining is studied. >
Jeffrey G Andrews - One of the best experts on this subject based on the ideXlab platform.
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transmission capacity of wireless ad hoc networks with Successive Interference Cancellation
IEEE Transactions on Information Theory, 2007Co-Authors: Steven Weber, Jeffrey G Andrews, Xiangying Yang, G De VecianaAbstract:The transmission capacity (TC) of a wireless ad hoc network is defined as the maximum spatial intensity of successful transmissions such that the outage probability does not exceed some specified threshold. This work studies the improvement in TC obtainable with Successive Interference Cancellation (SIC), an important receiver technique that has been shown to achieve the capacity of several classes of multiuser channels, but has not been carefully evaluated in the context of ad hoc wireless networks. This paper develops closed-form upper bounds and easily computable lower bounds for the TC of ad hoc networks with SIC receivers, for both perfect and imperfect SIC. The analysis applies to any multiuser receiver that cancels the K strongest interfering signals by a factor z isin [0, 1]. In addition to providing the first closed-form capacity results for SIC in ad hoc networks, design-relevant insights are made possible. In particular, it is shown that SIC should be used with direct sequence spread spectrum. Also, any imperfections in the Interference Cancellation rapidly degrade its usefulness. More encouragingly, only a few - often just one - interfering nodes need to be canceled in order to get the vast majority of the available performance gain.
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iterative power control for imperfect Successive Interference Cancellation
IEEE Transactions on Wireless Communications, 2005Co-Authors: A. Agrawal, Jeffrey G Andrews, J M Cioffi, T H MengAbstract:Successive Interference Cancellation (SIC) is a technique for increasing the capacity of cellular code-division multiple-access (CDMA) systems. To be successful, SIC systems require a specific distribution of the users' received powers, especially in the inevitable event of imperfect Interference Cancellation. This apparent complication of standard CDMA power control has been frequently cited as a major drawback of SIC. In this paper, it is shown that surprisingly, these "complications" come with no additional complexity. It is shown that 1-bit UP/DOWN power control-like that used in commercial systems-monotonically converges to the optimal power distribution for SIC with Cancellation error. The convergence is proven to within a discrete step-size in both signal-to-noise plus Interference ratio and power. Additionally, the algorithm is applicable to multipath and fading channels and can overcome channel estimation error with a standard outer power control loop.
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transmission capacity of cdma ad hoc networks employing Successive Interference Cancellation
Global Communications Conference, 2004Co-Authors: Steven Weber, Jeffrey G Andrews, Xiangying Yang, G De VecianaAbstract:Upper and lower bounds on the transmission capacity of direct-sequence CDMA wireless ad hoc networks are derived. The transmission capacity is a stochastic measure of the allowable number of transmissions per unit area, and is a generalization of previous measures of ad hoc network capacity. Successive Interference Cancellation (SIC) is attractive for DS-CDMA ad hoc networks since the dominant nearby interferers can be cancelled. Our closed-form results cleanly summarize the dependence of ad hoc network capacity on pathloss, spreading, outage probability, and Interference Cancellation accuracy. Other multiple access schemes, such as CSMA and DS-CDMA without SIC, are special cases. Perfect Interference Cancellation increases transmission capacity by nearly two orders of magnitude. Furthermore, cancelling just the strongest interferer generally gives the majority of the capacity gain, so the latency and complexity cost of SIC should be negligible.
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performance of multicarrier cdma with Successive Interference Cancellation in a multipath fading channel
IEEE Transactions on Communications, 2004Co-Authors: Jeffrey G Andrews, T H MengAbstract:A high capacity, low complexity, and robust system design for a Successive Interference Cancellation (SIC) system is developed and analyzed. Multicarrier code-division multiple access (MC-CDMA) is used to suppress multipath and to overcome the multipath channel estimation problem in single-carrier SIC systems. In addition, an optimal power control algorithm for MC-CDMA with SIC is derived, allowing analytical bit-error rate expressions to be found for an uncoded system. Low-rate forward error-correcting codes are then added to the system to achieve robustness. It is found that the capacity of the coded system approaches the additive white Gaussian noise capacity for SIC, even in a fading multipath channel with channel estimation error. This indicates that MC-CDMA is very attractive for systems employing SIC.
Jin Young Kim - One of the best experts on this subject based on the ideXlab platform.
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performance of a multicarrier ds cdma system with Successive Interference Cancellation
European Transactions on Telecommunications, 2002Co-Authors: Hoon Huh, Jin Young KimAbstract:In this paper, Successive Interference Cancellation (SIC) scheme is proposed for a multicarrier DS/CDMA system and its performance is analyzed in a Rayleigh fading channel. The SIC scheme is employed to mitigate performance degradation due to multiple access Interference (MAI) coupled with near-far problem. Bit error probability of the proposed system is derived for maximal-ratio and equal-gain combining schemes of subcarrier signals, respectively. From numerical results, it is shown that the proposed system achieves significant performance improvement over a conventional multicarrier DS/CDMA system. The proposed system can find application in multicarrier DS/CDMA systems for high-rate data services.
