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Virtual Resource Allocation in Virtualized Small Cell networks with physical-layer network coding Aided Self-Backhauls

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KSII TRANSACTIONS ON INTERNET AND INFORMATION SYSTEMS 2017年第8期11卷 3841-3861页

作者： Cheng, Yulun Yang, Longxiang Zhu, Hongbo Nanjing Univ Posts & Telecommun Jiangsu Key Lab Wireless Commun Nanjing 210003 Jiangsu Peoples R China

Virtualized small cell network is a promising architecture which can realize efficient utilization of the network resource. However, conventional full duplex self-backhauls lead to residual self-interference, which limits the network performance. To handle this issue, this paper proposes a virtual resource allocation, in which the residual self-interference is fully exploited by employing a physical-layer network coding (PNC) aided self-backhaul scheme. We formulate the features of PNC as time slot and information rate constraints, and based on that, the virtual resource allocation is formulated as a mixed combinatorial optimization problem. To solve the problem efficiently, it is decomposed into two sub problems, and a two-phase iteration algorithm is developed accordingly. In the algorithm, the first sub problem is approximated and transferred into a convex problem by utilizing the upper bound of the PNC rate constraint. On the basis of that, the convexity of the second sub problem is also proved. Simulation results show the advantages of the proposed scheme over conventional solution in both the profits of self-backhauls and utility of the network resource.

关键词： Virtual resource allocation wireless virtualization small cell wireless self-backhauls physical-layer network coding

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Amplitude variation phenomenon in optical physical-layer network coding with direct detection

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OPTICS COMMUNICATIONS 2022年 505卷 127579-127579页

作者： Xiong, Jian Lu, Lu Sun, Qifu Tyler Long, Keping Univ Sci & Technol Beijing Sch Comp & Commun Engn Beijing Peoples R China Univ Chinese Acad Sci Beijing Peoples R China Chinese Acad Sci Technol & Engn Ctr Space Utilizat Key Lab Space Utilizat Beijing Peoples R China

This paper studies the amplitude variation phenomenon in optical physical-layer network coding (OPNC) with intensity modulation and direct detection (IM/DD). Although PNC has been studied thoroughly in wireless communications, the application of PNC to optical communication networks is still challenging. In OPNC, two optical signals are transmitted simultaneously, and the received signals are overlapped in the optical field and then detected by a photo-detector (PD). Previous works assumed the OPNC signal and its electrical signal converted by a PD are linearly related. We find that the relationship is not the case. To fill this gap, we theoretically analyze OPNC and discover that an interference signal is generated when an OPNC signal is converted to its corresponding electrical PNC signal in most conditions. Besides, we implement the simulation and experiment to validate the theoretical analysis. The results coincide with our analysis and indicate that the PNC system does not work when the signal is severely damaged by the interference signal. However, we can recover the PNC signal by filtering the interference signal when their frequency spectrums are not aliasing. We further evaluate the BER performance in the simulation and experiment and found that when the frequency spectrum of the PNC signal is not aliased with the interference signal, using a low-pass filter can improve the BER performance by approximately 12 dB.

关键词： physical-layer network coding Optical communications Intensity modulation Direct detection Amplitude variation

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Short Packet physical-layer network coding with Mismatched Channel State Information

Short Packet Physical-layer Network Coding with Mismatched C...

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IEEE Wireless Communications and networking Conference (WCNC)

作者： Ullah, Shakeel Salamat Liva, Gianluigi Liew, Soung Chang Chinese Univ Hong Kong Dept Informat Engn Hong Kong Hong Kong Peoples R China German Aerosp Ctr DER Inst Commun & Networking Wessling Germany

ISBN: (纸本)9781538617342

Future multi-terminal communication networks such as machine-to-machine, telecommand and remote control communication systems will be based on short-packet transmissions. physical-layer network coding (PNC) in such multi-terminal communication systems can potentially enhance network throughput and reduce communication latency. For practical PNC systems, preambles are contained in transmissions for accurate estimation of the channel-state-information (CSI). Identifying good preamble-length regimes, however, is critical for good performance of short-packet PNC systems. Long preambles for short packets reduce spectral efficiency. On the other hand, short preambles compromise accuracy of estimated CSI, leading to sub-par packet error rate (PER) performance. This paper studies the impact of preamble length on the performance of short-packet PNC systems. Specifically, we use random coding bound to quantify PER of channel-coded mismatched-CSI PNC systems and identify the preamble-length regime that achieves the target PER with minimum E-b/N-o. As an example, we consider a simple yet practically relevant setup of a BPSK modulated PNC system in a two-way relay channel operating with short packets of 128 symbols. Our results show that a preamble of 20 to 30 symbols provides the minimum PER for a wide range of E-b/N-o and achieves a target PER of 10(-3) with minimum E-b/N-o.

关键词： Short packet mismatched decoding physical-layer network coding random coding bound channel-state-information

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A New LDPC coded Scheme for Two-user Multiple-Access Channels aided with physical-layer network coding

A New LDPC coded Scheme for Two-user Multiple-Access Channel...

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36th IEEE Global Communications Conference (IEEE GLOBECOM)

作者： Du, Junyi Zhou, Liang He, Xuan Peng, Shenglong Univ Elect Sci & Technol China Natl Key Lab Sci & Technol Commun Chengdu Sichuan Peoples R China

ISBN: (纸本)9781538639207

In this paper, we aim to design a new low-density parity-check (LDPC) coded scheme for two-user Gaussian multiple access channel aided with physical-layer network coding (PNC). The two users have equal transmission rate and employ the same LDPC code. We allocate the two users with unequal modulation power levels. Without loss of generality, we modulate User A's codeword and User B's codeword by the higher and lower power level signals, respectively. Since the PNC coded bits are the exclusive-OR (XOR) of User A's codeword and User B's codeword, the PNC coded bits are also a codeword of the employed LDPC code. At the receiver, the decoder estimates User A's codeword and the PNC codeword with conventional message passing algorithm separately, rather than decoding User A's and User B's codewords directly with the joint decoding algorithm. Then User B's codeword is estimated by the XOR of the decoding results of User A's codeword and the PNC codeword. We optimize the power ratio between the two power levels to minimize the required SNR for a scheme with a given rate. Numerical result shows that our proposed scheme has a better bit error rate performance and a lower decoding complexity, compared to the state-of-the-art scheme.

关键词： Low-density parity-check code physical-layer network coding multiple access channel

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Implementation of physical-layer network coding

Implementation of Physical-layer Network Coding

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IEEE International Conference on Communications (ICC)

作者： Lu, Lu Wang, Taotao Liew, Soung Chang Zhang, Shengli Chinese Univ Hong Kong Dept Informat Engn Hong Kong Hong Kong Peoples R China

ISBN: (纸本)9781457720536

This paper presents the first implementation of a two-way relay network based on the principle of physical-layer network coding. To date, only a simplified version of physical-layer network coding (PNC), called analog network coding (ANC), has been successfully implemented. The advantage of ANC is that it is simple to implement;the disadvantage, on the other hand, is that the relay amplifies the noise along with the signal before forwarding the signal. PNC systems in which the relay performs XOR or other denoising PNC mappings of the received signal have the potential for significantly better performance. However, their implementation also poses many challenges. For example, the relay must be able to deal with symbol and carrier-phase asynchronies of the simultaneous signals received from the two end nodes, and the relay must perform channel estimation before decoding. We investigate a PNC implementation in the frequency domain, referred to as FPNC, to tackle these challenges. FPNC is based on OFDM. In FPNC, XOR mapping is performed on the OFDM samples in each subcarrier rather than on the samples in the time domain. We implement FPNC on the universal soft radio peripheral (USRP) platform. Our implementation requires only moderate modifications of the packet preamble design of 802.11a/g OFDM PHY. With the help of the cyclic prefix (CP) in OFDM, symbol asynchrony and the multi-path fading effects can be dealt with simultaneously in a similar fashion. Our experimental results show that symbol-synchronous and symbol-asynchronous FPNC have essentially the same BER performance, for both channel-coded and unchannel-coded FPNC.

关键词： physical-layer network coding network coding implementation software radio

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Practical physical layer network coding for Two-Way Relay Channels: Performance Analysis and Comparison

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2010年第2期9卷 764-777页

作者： Louie, Raymond H. Y. Li, Yonghui Vucetic, Branka Univ Sydney Sch Elect & Informat Engn Telecommun Lab Sydney NSW 2006 Australia

This paper investigates the performance of practical physical-layer network coding (PNC) schemes for two-way relay channels. We first consider a network consisting of two source nodes and a single relay node, which is used to aid communication between the two source nodes. For this scenario, we investigate transmission over two, three or four time slots. We show that the two time slot PNC scheme offers a higher maximum sum-rate, but a lower sum-bit error rate (BER) than the four time slot transmission scheme for a number of practical scenarios. We also show that the three time slot PNC scheme offers a good compromise between the two and four time slot transmission schemes, and also achieves the best maximum sum-rate and/or sum-BER in certain practical scenarios. To facilitate comparison, we derive new closed-form expressions for the outage probability, maximum sum-rate and sum-BER. We also consider an opportunistic relaying scheme for a network with multiple relay nodes, where a single relay is chosen to maximize either the maximum sum-rate or minimize the sum-BER. Our results indicate that the opportunistic relaying scheme can significantly improve system performance, compared to a single relay network.

关键词： Two-way relaying physical-layer network coding

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Apply Uniquely-decodable Codes to Multiuser physical-layer network coding Based on Amplify-and-Forward Criterion

Apply Uniquely-decodable Codes to Multiuser Physical-layer N...

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IEEE Global Communications Conference

作者： Ya-Tian Li Qi-Yue Yu Kai He Wei Xiang Communications Research Center Harbin Institute of Technology School of Electronic and Information Engineering Xi'an Jiaotong University School of Mechanical and Electrical Engineering University of Southern Queensland

ISBN: (纸本)9781479959532

The physical-layer network coding (PNC) becomes a popular research topic, and the multiuser PNC network is still an open issue. This paper investigates the uniquely-decodable codes (UDC) by using Iterative construction algorithm, and applies the generated UDC to the multiuser PNC network that based on amplify-and-forward (AF) criterion. Due to the attractive features of UDC, the sum data rate can increase with the number of users log-linearly. Moreover, only two time slots are needed for any user node to obtain the data sequences transmitted by an arbitrary user, no matter of the users' number. It is also illustrated that the theoretical bit error rate (BER) of the proposed scheme, which can compare with the traditional PNC scheme in both simulated and theoretical results.

关键词： physical-layer network coding Multiuser network Uniquely-decodable codes Amplify-and-forward PNC hierarchical network physical layer network coding data sequence Bit error rate Codes Consumers

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Analysis of physical-layer network coding over Asymmetric Two-way Relay Channel with Carrier Frequency Offset

Analysis of Physical-layer Network Coding over Asymmetric Tw...

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IEEE/CIC International Conference on Communications in China

作者： Shouxin Zong Shaoshuai Gao School of Electronic Electrical and Communication Engineering University of Chinese Academy of Sciences Beijing China

ISBN: (纸本)9781509002443

The physical-layer network coding (PNC) can greatly improve the throughput of wireless network communications. However, critical synchronization in both time domain and frequency domain is required. Orthogonal frequency division multiplexing (OFDM) solves the problem of the synchronization in time domain while more critical synchronization in frequency domain is required. In this paper, we investigate the inter-channel interference (ICI) issue for OFDM-based physical-layer network coding (FPNC) over the two-way relay channel (TWRC). An approximate formula that calculates the ICI is derived. The compensation frequency, used by intermediate node to obtain minimal ICI power, has also been calculated. We find that average compensation is the optimal compensation method in the symmetric TWRC system while a different compensation method should be adopted in the asymmetric TWRC system. In addition, it is observed that bit error rate (BER) performance is not only decided by the power of the ICI but also by the distribution of it. At last, numerical results indicate that our approximate formula is accurate enough to calculate the ICI and can be applied to other OFDM systems.

关键词： physical-layer network coding carrier frequency offset inter-channel interference two-way relay channel carrier frequency offset Interchannel interference relay channel compensation method hierarchical network ICI physical layer approximate formula network coding TIME-DOMAIN Frequency-domain analysis Orthogonal frequency division multiplexing two-way channel intermediate node

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New evolution in two-way relay networks based on physical layer network coding

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TELECOMMUNICATION SYSTEMS 2019年第2期71卷 181-190页

作者： Dosaranian-Moghadam, Mohamad Mirrezaei, Seyed Masoud Yazdanpanahei, Maryam Islamic Azad Univ Qazvin Branch Fac Elect Biomed & Mechatron Engn Qazvin Iran Shahrood Univ Technol Dept Elect & Robot Engn Shahrood Iran Amirkabir Univ Technol Dept Elect Engn Hafez Ave Tehran Iran

In this paper, a physical-layer network coding (PNC) method is offered for a two-way relay network with spatial modulation (SM) for source node and relay node. For this purpose, we consider a two-way relay network consists of a single relay node and two source nodes both equipped with multiple antennas. It includes two source nods for transferring the data through SM and also, the relay node for decrypting coded packet network (through the XOR) of two packets received from the source node. In the proposed method, the signal detection approach with maximum-likelihood for the PNC with SM modulation is used for relay nodes. The simulation results show that the bit error rate (BER) in the relay node of the proposed method is significantly improved compared to the conventional method PNC;while the data rate is based on the same BER. It is worth mentioning that the performance of the proposed method, when the number of antenna nodes rises, is significant. And it leads to increase in the data rate which indicates that the proposed method will be much convenient for the next generation of wireless communication systems, especially the fifth generation. It should also be said that the suggested SM-based PNC method, does not need channel state information at transmitter. So it can be easily implemented in practice.

关键词： Wireless communications physical-layer network coding Multiple antennas Spatial modulation Maximum likelihood detection Channel coding

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Wireless Broadcast with physical-layer network coding

Wireless Broadcast with Physical-Layer Network Coding

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IEEE Global Communications Conference

作者： Shen Feng Soung C. Liew Dept. of Information Engineering The Chinese University of Hong Kong

ISBN: (纸本)9781479913510

This work investigates the maximum broadcast throughput and its achievability in multi-hop wireless networks with half-duplex node constraint. We allow the use of physical-layer network coding (PNC). Although the use of PNC for unicast has been extensively studied, there has been little prior work on PNC for broadcast. Our specific results are as follows: 1) For single-source broadcast, the theoretical throughput upper bound is n/(n+1), where n is the "min vertex-cut" size of the network. 2) In general, the throughput upper bound is not always achievable. 3) For grid and many other networks, the throughput upper bound n/(n+1) is achievable. Our work can be considered as an attempt to understand the relationship between max-flow and min-cut in half-duplex broadcast networks with cycles (there has been prior work on networks with cycles, but not half-duplex broadcast networks).

关键词： Wireless broadcast physical-layer network coding

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