Subchannel assignment in OFDM relay nodes

Hottinen, A.; Heikkinen, Tiina

doi:10.1109/ciss.2006.286667

Cited by 61 publications

(55 citation statements)

References 4 publications

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“…The exact optimal subcarrier assignment scheme considered in this paper was first introduced by Hottinen et al in [2]. Slightly later the scheme was independently discussed by Hammerström et al in [3], and Herdin proposed [4] a chunk-based pairing strategy that creates significantly less overhead when signaling subcarrier pair mapping to a single destination.…”

Section: Introductionmentioning

confidence: 99%

Analysis of subcarrier pairing in a cellular OFDMA relay link

Riihonen¹,

Wichman²,

Hämäläinen³

et al. 2008

2008 International ITG Workshop on Smart Antennas

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We consider a cellular OFDMA relay link consisting of a base station (BS), an infrastructure-based amplify-and-forward relay node (RN) and N active mobile user equipments (UEs). We study how to optimally pair the BS-RN subcarriers with the RN-UE subcarriers when the K subcarriers in the RN-UE channel are assigned for the UEs using round robin scheduling. The main contribution is to analyze the performance of the system by deriving closed-form expressions for average end-to-end SNR and capacity. The calculated measures facilitate performance evaluation that illustrates the benefit of channel-adaptive subcarrier pairing over fixed pairing.

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Section: Introductionmentioning

confidence: 99%

Analysis of subcarrier pairing in a cellular OFDMA relay link

Riihonen¹,

Wichman²,

Hämäläinen³

et al. 2008

2008 International ITG Workshop on Smart Antennas

Self Cite

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“…proposed [3], [4], where a different subchannel may be used over the second hop for signal relaying. This technique was actively studied recently in a few specific relay models [5], [7], [8], [10] for improving the end-to-end data rate.…”

Section: Achievable Ratementioning

confidence: 99%

“…It was first proposed independently in [3] and [4] for an amplified-and-forward (AF) dual-hop OFDM relay system. This has sparked interests in finding optimal channel pairing schemes [5]- [10].…”

Section: Introductionmentioning

confidence: 99%

Optimal Fixed Gain Linear Processing for Amplify-and-Forward Multichannel Relaying

Dong

Hajiaghayi

Liang

2012

IEEE Trans. Signal Process.

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In this paper, we consider the problem of linear processing design at the relay for amplified-andforward relaying in a multichannel system. Assuming a fixed-gain power amplification at the relay, we study the linear processing structure to maximize the end-to-end achievable rate. For both the cases of relaying with or without direct path, we show that the optimal unitary processing matrix is of permutation structure, i.e., channel pairing is optimal. Furthermore, in each case, the explicit optimal channel pairing strategy is obtained based on sorting certain function of received SNR over the incoming and outgoing subchannels. This result is especially noticeable for the case with direct path, where the optimal linear processing was not known before under any power allocation. Specifically, we show that the pairing is according to the ordering of the relative SNR ratio on a subchannel over first hop to its direct path, and that of SNR strengths on subchannels over the second hop. Simulation results are presented to demonstrate the achievable gain of optimal channel pairing over non-optimal linear processing or nopairing cases. It is also shown that the performance of channel pairing under the simple fixed-gain power allocation outperforms that under the traditional uniform power allocation.

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“…For an OFDM system as a typical example of multi-channel systems, the concept of CP was first introduced independently in [5] and [6] for a dual-hop AF relaying system where heuristic algorithms for pairing based on the order of channel quality were proposed. For relaying without the direct source-destination link available, [5] used integer programming to find the optimal pairing that maximizes the sum SNR.…”

Section: B Related Workmentioning

confidence: 99%

“…For relaying without the direct source-destination link available, [5] used integer programming to find the optimal pairing that maximizes the sum SNR. From a system-design perspective, the sorted-SNR CP scheme was proposed in [6] and was shown optimal for the noise-free relaying case, under the assumption of uniform power allocation.…”

Section: B Related Workmentioning

confidence: 99%

Optimal Channel Pairing and Power Allocation for Multi-channel Multi-hop Relay Networks

Hajiaghayi

Dong

Liang

2012

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering

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We study the problem of channel pairing and power allocation in a multi-channel multi-hop relay network to enhance the end-to-end data rate. Both amplify-and-forward (AF) and decode-and-forward (DF) relaying strategies are considered. Given fixed power allocation to the channels, we show that channel pairing over multiple hops can be decomposed into independent pairing problems at each relay, and a sorted-SNR channel pairing strategy is sum-rate optimal, where each relay pairs its incoming and outgoing channels by their SNR order. For the joint optimization of channel pairing and power allocation under both total and individual power constraints, we show that the problem can be decoupled into two subproblems solved separately. This separation principle is established by observing the equivalence between sorting SNRs and sorting channel gains in the jointly optimal solution. It significantly reduces the computational complexity in finding the jointly optimal solution. It follows that the channel pairing problem in joint optimization can be again decomposed into independent pairing problems at each relay based on sorted channel gains. The solution for optimizing power allocation for DF relaying is also provided, as well as an asymptotically optimal solution for AF relaying. Numerical results are provided to demonstrate substantial performance gain of the jointly optimal solution over some suboptimal alternatives. It is also observed that more gain is obtained from optimal channel pairing than optimal power allocation through judiciously exploiting the variation among multiple channels.Impact of the variation of channel gain, the number of channels, and the number of hops on the performance gain is also studied through numerical examples.

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Subchannel assignment in OFDM relay nodes

Cited by 61 publications

References 4 publications

Analysis of subcarrier pairing in a cellular OFDMA relay link

Analysis of subcarrier pairing in a cellular OFDMA relay link

Optimal Fixed Gain Linear Processing for Amplify-and-Forward Multichannel Relaying

Optimal Channel Pairing and Power Allocation for Multi-channel Multi-hop Relay Networks

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