Capacity of Two-Way Relay Channel

Zhang, Shengli; Liew, Soung Chang; Wang, Hui; Lin, Xiaohui

doi:10.1007/978-3-642-11664-3_17

Cited by 22 publications

(24 citation statements)

References 16 publications

(29 reference statements)

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“…After that, the relay maps r to 1 2 x x ⊕ according to the PNC mapping in [2]. As a result, in this new scheme, the relay can obtain 1 2 x x ⊕ with almost full rate [8][9][10]. This example shows that the proposed scheme may outperform the MIMO NC scheme significantly.…”

Section: B Illustrating Examplementioning

confidence: 99%

Physical Layer Network Coding with Multiple Antennas

Zhang

Liew

2010

2010 IEEE Wireless Communication and Networking Conference

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The two-phase MIMO NC (network coding) scheme can be used to boost the throughput in a two-way relay channel in which nodes are equipped with multiple antennas. The obvious strategy is for the relay node to extract the individual packets from the two end nodes and mix the two packets to form a network-coded packet. In this paper, we propose a new scheme called MIMO PNC (physical network coding), in which the relay extracts the summation and difference of the two end packets and then converts them to the network-coded form. MIMO PNC is a natural combination of the single-antenna PNC scheme and the linear MIMO detection scheme. The advantages of MIMO PNC are many. First, it removes the stringent carrier-phase requirement in single-antenna PNC. Second, it is linear in complexity with respect to the constellation size and the number of simultaneous data streams in MIMO. Simulation shows that MIMO PNC outperforms the straightforward MIMO NC significantly under random Rayleigh fading channel. Based on our analysis, we further conjecture that MIMO PNC outperforms MIMO NC under all possible realizations of the channel. I. INTRODUCIONIn wireless networks, the use of relay has many advantages. It can lead to better coverage and connectivity. With a smaller distance for node-to-node transmissions, the power consumption can be reduced. At the same time, the detrimental effects of the interferences from other transmissions can be alleviated, leading to higher capacity per unit area.Consider the simple two-way relay channel (TWRC) shown in Fig. 1. In [1], the authors introduced network coding into TWRC: the two end nodes transmit their packets to the relay in two different time slots; the relay then forms a network-coded packet out of the two packets and broadcast it to the end nodes. The number of time slots needed to exchange one packet is 3. Subsequent to [1], we proposed physical layer network coding (PNC) [2]. PNC allows the two end nodes to transmit their packets in the same time slot. The superimposed packets received simultaneously are then directly transformed to a network-coded packet at the physical layer of the relay. As a result, the number of time slots needed to exchange one packet is reduced to 2.PNC is attracting increasing attention. At the communication level, variants of PNC have been proposed [3,4,5] to improve performance or to ease implementation. At the network level, PNC has also been shown to be able to increase network capacity by a fixed factor [6,7]. In addition, information-theoretic studies indicate that PNC can allow the capacity of TWRC to be approached in both low SNR and high SNR regions [8,9,10].

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Section: B Illustrating Examplementioning

confidence: 99%

Physical Layer Network Coding with Multiple Antennas

Zhang

Liew

2010

2010 IEEE Wireless Communication and Networking Conference

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“…In Two-Way Relay Channel (TWRC), physical layer network coding (PNC) [1] is an attractive transmission scheme that can approach the TWRC capacity in theory under perfect synchronization [2], [3] and can boost the wireless system performance in practice under non-perfect synchronization [4], [5]. In PNC, the transmission can be divided into uplink phase and downlink phase.…”

Section: Introductionmentioning

confidence: 99%

Channel quantization based physical-layer network coding

Zhang

Zhou

Kai

et al. 2013

2013 IEEE International Conference on Communications (ICC)

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This paper studies a MIMO Two-Way Relay Channel (TWRC) where two single-antenna nodes communicate with each other through a K-antenna relay. In the uplink phase, the two end nodes send their respective information simultaneously to the relay, and it is usually regarded as a virtual MIMO system. With traditional VBLAST MIMO detection, the maximum achievable diversity is K − 1. By noting that only the network coded packet, rather than the two individual packets, is needed at the relay node in TWRC, we propose a channel quantized physical-layer network coding (CQ-PNC) scheme based on VBLAST to achieve the full diversity K. Specifically, relay first uses QR decomposition to convert the K received signals into two valid signals, the first signal is a weighted summation of the two end nodes' symbols and the second signal is a scaled version of one end node's symbol. The relay first quantizes the first signal with the channel coefficient of one node and estimate the Gaussian integer summation of the two end nodes' information. At the same time, the quantization error is further canceled with the help of the second signal. After that, we adaptively map the Gaussian integer weighted summation to the network coding form. Moreover, we theoretically prove that our CQ-PNC can achieve the maximum diversity K. Finally, the numerical simulation shows that CQ-PNC performs within 2dB gap from the theoretical bound.

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“…PLNC can further be classed into two categories -PNCF (PNC over finite field) and PNCI (PNC over infinite field) -according to whether the network coding field adopted is finite or infinite [3]. The capacity of TWRC with PLNC is higher than the traditional communication strategies [4,5]. The design of modulation suited for TWRC with PLNC can be BPSK or QPSK [6], and an unconventional 5-ary modulation which is optimized according to the channel condition [7].…”

Section: Introductionmentioning

confidence: 99%

A novel design of physical layer network coding in strong asymmetric two-way relay channels

Wei

Zheng

2013

J Wireless Com Network

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The quality of two-way links is always asymmetric in practical two-way relay channels (TWRC) and therefore, the capacity of TWRC will be limited by the weaker link. An asymmetric modulation scheme, with physical layer network coding, was presented in order to improve the transmission reliability in TWRC. This makes full use of the stronger link to improve the overall transmission rate and also ensures the reliability of the weaker link. The simulation results show that the proposed asymmetric modulation scheme in the case of strongly asymmetric channels, compared to the symmetric transmission, enhances the system capacity significantly and also guarantees the system reliability.

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Capacity of Two-Way Relay Channel

Cited by 22 publications

References 16 publications

Physical Layer Network Coding with Multiple Antennas

Physical Layer Network Coding with Multiple Antennas

Channel quantization based physical-layer network coding

A novel design of physical layer network coding in strong asymmetric two-way relay channels

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