Optimizing Zero-Forcing Based Gain Allocation for Wireless Multiuser Networks

Esli, C.; Berger, S.; Wittneben, A.

doi:10.1109/icc.2007.965

Cited by 18 publications

(16 citation statements)

References 9 publications

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“…The additional 4(2) orders of diversity come from the intra cluster gain allocations. This is consistent with the results of [5] presenting that maxmin rate gain allocation maximizes the diversity in MUZFR applications. It is noticable that for 4 clusters with 3 relays, the system offers only 4th order of phase diversity, but no intra cluster diversity.…”

Section: Simulation Resultssupporting

confidence: 92%

“…Fig. 5 presents a comparison between the proposed C-MUR, MUZFR [5] and relaying with only local CSI (RLCSI) at the relays [4]. Both C-MUR and MUZFR use maxmin rate gain allocations.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…A minimum number of relays is needed to achieve this. When there are more relays, the gain factors can be further optimized [5].…”

Section: Introductionmentioning

confidence: 99%

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A Cluster-Based Multiuser Cooperative Network

Esli

Wittneben

2007

IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference

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Abstract-A novel cluster-based coherent multi-user (MU) relaying system is proposed, where a number of source/destination pairs communicate concurrently over the same physical channel and a set of amplify-and-forward relays assist them. A secondary short-range wireless system with single/multi-hop unicast or broadcast ability is considered for the channel state information (CSI) dissemination. To reduce the CSI dissemination overhead, the relays are grouped in several independent clusters. Distributed diversity gain is attained at the destinations by applying phase rotations between clusters. The CSI dissemination is analyzed thoroughly, and compared with that of previous works on MU relaying. It is shown that for a given number of clusters and relays, the most uniform distribution of relays to clusters is optimum to minimize the CSI exchange traffic overhead and transmit energy consumption for CSI dissemination; besides it maximizes the average achievable rate for source/destination links. Furthermore, a new solution for a maxmin fairness based relay gain allocation is proposed and formulated as a semidefinite program.

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Section: Simulation Resultssupporting

confidence: 92%

“…Fig. 5 presents a comparison between the proposed C-MUR, MUZFR [5] and relaying with only local CSI (RLCSI) at the relays [4]. Both C-MUR and MUZFR use maxmin rate gain allocations.…”

Section: Simulation Resultsmentioning

confidence: 99%

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A Cluster-Based Multiuser Cooperative Network

Esli

Wittneben

2007

IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference

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“…For K-user 2-hop networks with L relays, it was shown in [9] that interference can be completely neutralized if K ≥ N (N − 1) + 1, which indicates that for 2 × L × 2 networks interference neutralization can be achieved without channel pairing if L ≥ 3. However, maximizing the achievable sum rate exploiting interference neutralization without channel pairing presented in [32] is non-convex and, as a result, it is unclear how to determine the sum rate gap from the cut-set upper bound. By contrast, we now show that our achievable rate expression from Theorem 1 permits to derive a finite-gap result.…”

Section: B Approximate Capacity As L → ∞mentioning

confidence: 99%

Approximate Ergodic Capacity of a Class of Fading Two-User Two-Hop Networks

Jeon

Wang

Gastpar

2014

IEEE Trans. Inform. Theory

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We consider a fading AWGN 2-user 2-hop network where the channel coefficients are independent and identically distributed (i.i.d.) drawn from a continuous distribution and vary over time. For a broad class of channel distributions, we characterize the ergodic sum capacity to within a constant number of bits/sec/Hz, independent of signal-to-noise ratio. The achievability follows from the analysis of an interference neutralization scheme where the relays are partitioned into M pairs, and interference is neutralized separately by each pair of relays. When M = 1, the proposed ergodic interference neutralization characterizes the ergodic sum capacity to within 4 bits/sec/Hz for i.i.d. uniform phase fading and approximately 4.7 bits/sec/Hz for i.i.d. Rayleigh fading. We further show that this gap can be tightened to 4 log π − 4 bits/sec/Hz (approximately 2.6) for i.i.d. uniform phase fading and 4 − 4 log( Index TermsAmplify-and-forward, approximate capacity, ergodic capacity, fading, interference neutralization, two unicast, two-user two-hop networks.

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“…Assuming that the CSI of both the source-relay and relay-destination channels is known to the relays, then, signal detection and transmission at the relays can be represented by one joint optimization problem, which is referred to as the joint detection/transmission relay optimization. This joint relay optimization problem may be solved in the principles of, such as, MMSE [2][3][4] or ZF [5]. However, this joint detection/transmission relay optimization problem is usually hard to solve.…”

mentioning

confidence: 99%

Spectral-Efficiency of TDD Multiuser Two-Hop MC-CDMA Systems Employing Egocentric-Altruistic Relay Optimization

Liu

Yang

2010

2010 IEEE 71st Vehicular Technology Conference

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Abstract-In this contribution we investigate the spectral-efficiency of a two-hop cooperative network using multicarrier code-division multipleaccess (MC-CDMA) transmission scheme. The two-hop network constitutes K source users transmitting signals to K destinations with the aid of N relays. Our focus is on the relay optimization, when assuming that the N relays cooperate or do not cooperate with each other. Specifically, in this contribution the egocentric-altruistic (E-A) optimization is introduced, which constitutes an E-optimization motivating to suppress the multiuser interference (MUI) of the source-relay channels and an A-optimization aiming to pre-mitigate the potential MUI of the relay-destination channels. Both the minimum mean-square error (MMSE) and zero-forcing (ZF) optimization criteria are considered. Furthermore, the spectral-efficiency performance of the two-hop MC-CDMA systems using the proposed E-A relay optimization is investigated by simulations, when assuming communications over frequency-selective fading channels. I. INTRODUCTIONIn order to increase the link quality, reliability, and data rate of wireless networks, future wireless communication systems are required to be developed for cooperation rather than merely for coexistence [1]. In order to accomplish such cooperation, relay nodes may be deployed to assist the communications between sources and destinations, making the signal processing at sources and destinations simple in addition to the other advantages. Specifically, in a two-hop network operated in time-division duplex (TDD) principles, the main signal processing may be implemented at the relays so that the complexity of source and destination devices is as low as possible.In TDD-based networks, owing to the reciprocal characteristics of the bidirectional communication channels, it is usually convenient for relays to attain the channel state information (CSI) required for carrying out some signal processing. Assuming that the CSI of both the source-relay and relay-destination channels is known to the relays, then, signal detection and transmission at the relays can be represented by one joint optimization problem, which is referred to as the joint detection/transmission relay optimization. This joint relay optimization problem may be solved in the principles of, such as, MMSE [2][3][4] or ZF [5]. However, this joint detection/transmission relay optimization problem is usually hard to solve. Therefore, in this contribution we propose and investigate a relatively simple relay optimization scheme, which is developed based on the concepts of egocentric (E)-optimization and altruistic (A)-optimization [8,9], referred to as the E-A optimization or E-A relay optimization for convenience. As our forthcoming discourse shown, the E-A relay optimization is constituted by an E-optimization resulting in a multiuser detector (MUD) and an A-optimization leading to a multiuser transmitter (MUT). The MUD motivates to suppress the MUI from the source-relay channels and the MUT aims to pre-mitiga...

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Optimizing Zero-Forcing Based Gain Allocation for Wireless Multiuser Networks

Cited by 18 publications

References 9 publications

A Cluster-Based Multiuser Cooperative Network

A Cluster-Based Multiuser Cooperative Network

Approximate Ergodic Capacity of a Class of Fading Two-User Two-Hop Networks

Spectral-Efficiency of TDD Multiuser Two-Hop MC-CDMA Systems Employing Egocentric-Altruistic Relay Optimization

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