In a bi-directional relay channel, two nodes wish to exchange independent messages over a shared wireless half-duplex channel with the help of relays. Recent work has considered information theoretic limits of the bi-directional relay channel with a single relay. In this work we consider bi-directional relaying with multiple relays. We derive achievable rate regions and outer bounds for half-duplex protocols with multiple decode and forward relays and compare these to the same protocols with amplify and forward relays in an additive white Gaussian noise channel. We consider three novel classes of half-duplex protocols: the (m,2) 2 phase protocol with m relays, the (m,3) 3 phase protocol with m relays, and general (m, t) Multiple Hops and Multiple Relays (MHMR) protocols, where m is the total number of relays and 3<t< m+3 is the number of temporal phases in the protocol. The (m,2) and (m,3) protocols extend previous bi-directional relaying protocols for a single m=1 relay, while the new (m,t) protocol efficiently combines multi-hop routing with message-level network coding. Finally, we provide a comprehensive treatment of the MHMR protocols with decode and forward relaying and amplify and forward relaying in the Gaussian noise, obtaining their respective achievable rate regions, outer bounds and relative performance under different SNRs and relay geometries, including an analytical comparison on the protocols at low and high SNR.
This letter analyzes and compares the performance of full-duplex relaying (FDR) and half-duplex relaying (HDR) for ultra-reliable short-packet communications. Specifically, we derive both approximate and asymptotic closed-form expressions of the block error rate (BLER) for FDR and HDR using short packets with finite blocklength codes. We define and attain a closed-form expression of a critical BLER, which can be used to efficiently determine the optimal duplex mode for ultra-reliable low latency communication scenarios. Our results unveil that FDR is more appealing to the system with relativel…
The hybrid half-duplex/full-duplex (HD/FD) relaying scheme is an effective paradigm to overcome the negative effects of the self-interference incurred by the full-duplex (FD) mode. However, traditional hybrid HD/FD scheme does not consider the diversity gain incurred by the multiple antennas of the FD node when the system works in the HD mode, leading to the waste of the system resources. In this paper, we propose a new hybrid HD/FD relaying scheme, which utilizes both the antennas of the FD relay node for reception and transmission when the system works in the HD mode. With multiple antennas,…
Full-Duplex Relay with Jamming Protocol for Improving Physical-Layer Security
该文提出了一种基于全双工中继的联合协作中继和干扰协议,以提高不同类型窃听者存在时的源-目的保密率。在这种所谓的\textit{FD-Relay with jamming (FDJ)}协议中,首先,FD中继器同时接收数据并向窃听者发送干扰,然后,转发数据,而源对窃听者进行干扰。在存在不同窃听者类型和自干扰(SI)的情况下,导出了建议FDJ的可扩展保密率,并与传统的半双工(HD)中继进行了比较。提出的FDJ和HD中继器在多载波情况下的保密率最大化的自适应功率分配制定为一个非凸优化问题和相应的迭代求解算法开发使用的两个凹函数(DC)的差异规划技术。仿真结果证实,FDJ提供了显着的改进,在保密率超过HD中继。
Full-duplex (FD) communication has received great interest in recent years due to the potential of doubling the spectral efficiency. However, how to alleviate the detrimental effects of the residual self-interference (RSI) incurred by the FD mode is still a challenging problem. In this paper, focusing on the statistical throughput maximization, we propose an optimal hybrid FD/half-duplex (HD) scheme for the one-way FD buffer aided relay system. To solve this problem, we divide the system into four different transmission modes and formulate the problem as a binary integer programming problem. B…
In order to satisfy the delay requirements of telecommunication systems, in this paper, we present a cooperative network with the short packet transmission in the Rayleigh fading channel. The desired relay can be implemented as a two-way half-duplex (HD) or a two-way full-duplex (FD). Also, for more accurate satisfaction and reduction of communication delays, sending and receiving with short packets is considered. Effective capacity appropriately measures the transmission rate under the delay constraint. Therefore, it is considered as a performance evaluation criterion here. With a two-way rel…
Cooperative Strategies for the Half-Duplex Gaussian Parallel Relay Channel: Simultaneous Relaying versus Successive Relaying
研究了在加性高斯白噪声环境下,两个半双工并联继电器组成的网络的通信问题。两个协议,即,提出了与两种可能的中继排序相关联的\emph{Simultaneous}和\emph{Successive}中继。同时中继协议基于\emph{Dynamic Decode and Forward (DDF)}方案。对于连续中继协议:(i)考虑基于\emph{Dirty Paper Coding (DPC)}的\emph{Non-Cooperative}方案,以及(ii)考虑基于\emph{Block Markov Encoding (BME)}的\emph{Cooperative}方案。此外,与\emph{Cooperative}方案相比,在一个中继器处采用BME而在另一个中继器处采用DPC的复合方案总是实现更好的速率。还提出了一种\emph{"Simultaneous-Successive Relaying based on Dirty paper coding scheme" (SSRD)}。中继的最佳顺序,从而在低和高的信号噪声比(SNR)的情况下,半双工高斯并行中继信道的容量推导。在低信噪比的情况下,它揭示了在一定的条件下的信道系数,基于DDF的同时中继的可达速率的割集界的比值趋于1。另一方面,当信噪比趋于无穷大时,证明了基于DPC的连续中继渐近地达到网络的容量。
Robust transceiver design against unresolvable system uncertainties is of crucial importance for reliable communication. For instance, full-duplex communication suffers from such uncertainties when canceling the self-interference, since the residual self-interference (RSI) remains uncanceled due to imperfect channel knowledge. We consider a MIMO multi-hop system, where the source, the relay and the destination are equipped with multiple antennas. We allow multi-stream beamforming granted by MIMO technique, without restricting the transmissions to single streaming. The relay can operate in eith…
This paper considers Gaussian half-duplex diamond $n$-relay networks, where a source communicates with a destination by hopping information through one layer of $n$ non-communicating relays that operate in half-duplex. The main focus consists of investigating the following question: What is the contribution of a single relay on the approximate capacity of the entire network? In particular, approximate capacity refers to a quantity that approximates the Shannon capacity within an additive gap which only depends on $n$, and is independent of the channel parameters. This paper answers the above q…
We consider a multi-pair two-way amplify-and-forward massive multi-input multi-output (MIMO) hybrid relay with MIMO user-pairs. A hybrid relay has lesser number of radio frequency (RF) chains than the antennas, which significantly reduces the implementation cost. We employ block-diagonalization-based baseband processing at the hybrid relay to cancel the inter user-pair interference and equal-gain-combining-based RF processing to maximize the beamforming gain. We also use an algebraic norm maximizing relay transmit strategy to maximize the spectral efficiency (SE) of each user-pair. We numerica…
In this paper, a symbol-level selective transmission for full-duplex (FD) relaying networks is proposed to mitigate error propagation effects and improve system spectral efficiency. The idea is to allow the FD relay node to predict the correctly decoded symbols of each frame, based on the generalized square deviation method, and discard the erroneously decoded symbols, resulting in fewer errors being forwarded to the destination node. Using the capability for simultaneous transmission and reception at the FD relay node, our proposed strategy can improve the transmission efficiency without extr…
We investigate physical-layer security of the full-duplex (FD) amplify-and-forward (AF) relay channel. We provide a new perspective on the problem and show that the processing time (delay) at the relay can be exploited to improve the system's security. We show that the FD AF relay channel can be seen as an intersymbol-interference (ISI) channel, hence, the discrete-Fourier transform (DFT) can be used for data modulation and demodulation to convert the frequency-selective channel into flat-fading channel per sub-channel/sub-carrier. By exploiting the fact that the channel memory needs to be cle…