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Non-Uniform 2-Slot Constellations for Relaying in Butterfly network with Imperfect Side Information

IEEE COMMUNICATIONS LETTERS 2012年第9期16卷 1369-1372页

作者： Uricar, Tomas Sykora, Jan Czech Tech Univ Fac Elect Engn Dept Radio Engn Prague Czech Republic

There are two key aspects affecting the performance of butterfly network with wireless network-coded relaying. The first one is the amount of Complementary Side Information (C-SI) at destinations and the second is given by a parametric Multiple-Access channel performance of source constellation alphabets. In this paper we show that the Non-uniform 2-slot (NuT) constellations, proposed originally for bi-directional relaying in the 2-Way Relay Channel (2-WRC), are suitable also for the butterfly network, combining the favorable parametric channel performance with the potential to increase the reliability of required C-SI (necessary for successful decoding at the final destination). Possessing both these qualities, the NuT alphabets surpass again the conventional linear modulation schemes, extending further the scope of their potential application.

关键词： Butterfly network imperfect side information non-uniform 2-slot constellations wireless network coding

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wireless network coding by amplify-and-forward for bi-directional traffic flows

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IEEE COMMUNICATIONS LETTERS 2007年第1期11卷 16-18页

作者： Popovski, Petar Yomo, Hiroyuki Univ Aalborg Dept Elect Syst DK-9220 Aalborg Denmark

This paper introduces and analyzes relaying techniques that increase the achievable throughput in multi-hop wireless networks by applying network coding over bi-directional traffic flows. We term each such technique as Bi-directional Amplification of Throughput (BAT)-relaying. While network coding is normally performed by combining decoded packets, here we introduce a relaying method based on Amplify-and-Forward (AF), where the relay node utilizes the inherent combining of packets provided by simultaneous transmissions over a multiple access channel. Under low noise levels, AF BAT-relaying offers a superior throughput performance. The unconventionality of AF BAT relaying opens many possibilities for further research.

关键词： wireless network coding wireless relay bidirectional communication amplify-and-forward decode-and-forward

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A network coding based interference cancelation scheme for wireless ad hoc networks

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wireless COMMUNICATIONS & MOBILE COMPUTING 2010年第8期10卷 1017-1032页

作者： Chen, Chen Bai, Lin Cai, Kai He, Jianhua Xiang, Haige Swansea Univ Inst Adv Telecommun Swansea SA2 8PP W Glam Wales Peking Univ Sch Elect Engn & Comp Sci Beijing 100871 Peoples R China Chinese Acad Sci Inst Comp Technol Beijing Peoples R China

The performance of wireless networks is limited by multiple access interference (MA!) in the traditional communication approach where the interfered signals of the concurrent transmissions are treated as noise. In this paper, we treat the interfered signals from a new perspective on the basis of additive electromagnetic (EM) waves and propose a network coding based interference cancelation (NCIC) scheme In the proposed scheme, adjacent nodes can transmit simultaneously with careful scheduling;therefore, network performance will not be limited by the MAI. Additionally we design a space segmentation method for general wireless ad hoc networks, which organizes network into clusters with regular shapes (e.g., square and hexagon) to reduce the number of relay nodes. The segmentation method works with the scheduling scheme and can help achieve better scalability and reduced complexity. We derive accurate analytic models for the probability of connectivity between two adjacent cluster heads which is important for successful information relay. We proved that with the proposed NCIC scheme, the transmission efficiency can be improved by at least 50% for general wireless networks as compared to the traditional interference avoidance schemes. Numeric results also show the space segmentation is feasible and effective Finally we propose and discuss a method to implement the NCIC scheme in a practical orthogonal frequency division multiplexing (OFDM) communications networks. Copyright (C) 2009 John Wiley & Sons, Ltd.

关键词： wireless ad hoc networks wireless network coding interference cancelation cross-layer design

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PIE: Cooperative Peer-to-Peer Information Exchange in network coding Enabled wireless networks

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IEEE TRANSACTIONS ON wireless COMMUNICATIONS 2010年第3期9卷 945-950页

作者： Fan, Yanfei Jiang, Yixin Zhu, Haojin Shen, Xuemin (Sherman) Univ Waterloo Dept Elect & Comp Engn Waterloo ON N2L 3G1 Canada Tsinghua Univ Dept Comp Sci & Technol Beijing 100084 Peoples R China Shanghai Jiao Tong Univ Dept Comp Sci & Engn Shanghai 200030 Peoples R China

In this paper, we study the issue of scheduling transmission opportunities among nodes (peers) to achieve higher network throughput and lower transmission delay for network coding enabled wireless networks. By conducting an in-depth investigation on the scheduling principles, we propose a cooperative Peer-to-peer Information Exchange (PIE) scheme with an efficient and light-weight scheduling algorithm. PIE can not only fully exploit the broadcast nature of wireless channels, but also take advantage of cooperative peer-to-peer information exchange. Qualitative analysis and extensive simulations demonstrate the effectiveness and efficiency of PIE.

关键词： cooperative peer-to-peer wireless network coding scheduling

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Opportunistic scheduling for wireless network coding

Opportunistic scheduling for wireless network coding

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IEEE International Conference on Communications (ICC 2007)

作者： Yomo, Hiroyuki Popovski, Petar Aalborg Univ Ctr TeleInfrastruct CTIF Dept Elect Syst DK-9220 Aalborg Denmark

ISBN: (纸本)9781424403523

This paper addresses a scheduling problem for wireless network coding which has been recently proposed as a novel method to enhance the throughput in wireless networks. The wireless network coding involves broadcast transmission of a network-coded packet which contains unicast data to several receiving nodes. These receiving nodes have time-varying fading links to the transmitting node, which can generate different instantaneous conditions for different links. In this paper, we introduce an opportunistic scheduling for such a wireless network coding, which selects a set of nodes whose packets are network-coded as well as the data rate for the broadcast transmission according to the instantaneous link conditions. We analyze the average capacity of such a scheduling, and discuss the impact of different parameters on the average capacity. We show that the opportunistic scheduling can maximize the average capacity by choosing the appropriate set of network-coded nodes according to the instantaneous link conditions. We also discuss the practical factors which can additionally affect the best scheduling strategy for wireless network coding.

关键词： wireless network coding time-varying fading rate adaptation opportunistic scheduling

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Non-Uniform 2-Slot Constellations for Bidirectional Relaying in Fading Channels

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IEEE COMMUNICATIONS LETTERS 2011年第8期15卷 795-797页

作者： Uricar, Tomas Sykora, Jan Czech Tech Univ Fac Elect Engn Dept Radioengn CR-16635 Prague Czech Republic

In this paper we introduce the constellation alphabets suitable for bidirectional relaying in parametric wireless channels. Based on the analysis of hierarchical minimum distance, we present a simple design algorithm for the non-uniform 2-slot constellation alphabets. These novel constellation alphabets outperform traditional linear modulation schemes in Hierarchical-Decode-and-Forward and Denoise-and-Forward relaying strategies in fading channels without sacrificing the overall system throughput.

关键词： Bidirectional relaying hierarchical-decode-and-forward wireless network coding

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Layered Design of Hierarchical Exclusive Codebook and Its Capacity Regions for HDF Strategy in Parametric wireless 2-WRC

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2011年第7期60卷 3241-3252页

作者： Sykora, Jan Burr, Alister Czech Tech Univ Fac Elect Engn Prague 16636 Czech Republic Univ York York YO10 5DD N Yorkshire England

This paper addresses a hierarchical decode-and-forward (HDF) strategy in the wireless two-way relay channel (2-WRC). This strategy uses a Hierarchical eXclusive Code (HXC) that allows full decoding of the hierarchical symbols at the relay. The HXC represents two data sources only through the exclusive law and requires side information on the complementary data at the destination (which naturally holds for the 2-WRC). The HDF strategy has the advantage over classical medium-access control (MAC) stage relaying with joint decoding in that its rate region extends beyond the classical MAC region. We present a layered design of the HXC codebook, which uses an arbitrary outer state-of-the-art capacity-approaching code [e.g., low density parity check (LDPC)] and an inner layer with an exclusive symbol alphabet. We provide basic theorems, showing that this scheme forms an HXC, and we also evaluate its alphabet-constrained rate regions. The rate regions depend on the relative channel phase parameters. Some channel rotation leads to catastrophic violation of the exclusive law. However, these values appear only in a limited range of phases and have only a mild impact on the mean capacity for some component symbol constellations.

关键词： Capacity region network coded modulation two-way relay channel wireless network coding

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On Performance of Bi-directional Cognitive Radio networks

On Performance of Bi-directional Cognitive Radio Networks

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17th Asia-Pacific Conference on Communications (APCC)

作者： Ligata, Amir Gacanin, Haris Adachi, Fumiyuki IPSA Inst Dept Commun Sarajevo Bosnia & Herceg Alcatel Lucent Bell NV Mot Div Antwerp Belgium Tohoku Univ Grad Sch Engn Sendai Miyagi Japan

ISBN: (纸本)9781457703881;9781457703898

Future wireless Internet services require a broadband frequency spectrum with high data rates. Cognitive radio (CR) concept is a novel approach to improve the spectrum efficiency. The CR is based on the opportunistic usage of frequency spectrum, which is not occupied by the primary users. Conventional multi-user access in bi-directional CR network may be done by using either time division multiple access (TDMA), frequency division multiple access (FDMA) or code division multiple access (CDMA). Without adaptive or dynamic frequency reuse, TDMA and FDMA have lower spectrum efficiency in comparison with CDMA. However, the problem of CDMA in a multipath channel is a multi-user interference (MUI). In this paper, we present a bi-directional CR network with wireless network coding (WNC) in a multipath channel. Unlike the conventional multi-user bi-directional CR network, where the users access the spectrum holes in different time-slot or frequency, the proposed method allows secondary users (SUs) to access the spectrum holes simultaneously. The performance of bi-directional CR network with WNC is theoretically analyzed in terms of spectrum efficiency and the maximum number of SUs. The numerical results show that the spectrum efficiency and the maximum number of SUs of the proposed method increases in comparison with conventional CR network.

关键词： Cognitive radio wireless network coding NC-OFDM spectrum efficiency

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On the Complementary Index coding Problem

On the Complementary Index Coding Problem

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IEEE International Symposium on Information Theory (ISIT)

作者： Chaudhry, M. A. R. Asad, Z. Sprintson, A. Langberg, M. Texas A&M Univ Dept Elect & Comp Engn College Stn TX 77843 USA Open Univ Israel Div Comp Sci Raanana Israel

ISBN: (纸本)9781457705953

The Index coding problem is one of the basic problems in wireless network coding. In this problem, a server needs to deliver a set P of packets to several clients through a noiseless broadcast channel. Each client needs to obtain a certain subset of P and has prior side information about a different subset of P. The objective is to satisfy the requirements of all clients with the minimum number of transmissions. Recently, it was shown that the Index coding problem is NP-hard. Furthermore, this problem was shown to be hard to approximate under a widely accepted complexity assumption. In this paper, we consider a complementary problem whose goal is to maximize the number of saved transmissions, i.e., the number of transmissions that are saved by combining packets compared to the solution that does not involve coding. We refer to this problem as the the Complementary Index coding problem. It turns out that the complementary problem can be approximated in certain cases of practical importance. We consider the multiple unicast and multiple multicast scenarios. In the multiple unicast scenario, each packet is requested by a single client;while in the multiple multicast scenario, each packet can be requested by several clients. For the multiple unicast scenario, we present approximation algorithms for finding scalar and vector linear solutions. For the multiple multicast scenario, we show that finding an approximation solution is NP-hard.

关键词： Approximation algorithms Approximation methods Encoding Indexes NP-hard problem Servers Unicast Vectors approximation algorithms approximation theory broadcast channels channel coding complementary index coding problem computational complexity multicast communication multiple multicast scenario multiple unicast scenario network coding noiseless broadcast channel radio networks wireless network coding

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Physical Layer network coding for wireless Cooperative Multicast Flows

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IEICE TRANSACTIONS ON COMMUNICATIONS 2009年第8期E92B卷 2559-2567页

作者： Li, Jun Chen, Wen Shanghai Jiao Tong Univ Dept Elect Engn Shanghai 200240 Peoples R China

It has been proved that wireless network coding can increase the throughput of multi-access system [2] and bi-directional system [5] by taking the advantage of the broadcast nature of electromagnetic waves. In this paper, we introduce the wireless network coding to cooperative multicast system. We establish a basic 2-source and 2-destination cooperative system model with arbitrary number of relays (2 - N - 2 system). Then two regenerative network coding (RNC) protocols are designed to execute the basic idea of network coding in complex field (RCNC) and Galois field (RGNC) respectively. We illuminate how network coding can enhance the throughput distinctly in cooperative multicast system. Power allocation schemes as well as precoder design are also carefully studied to improve the system performance in terms of system frame error probability (SFEP).

关键词： wireless network coding multicast systems system frame error probability power allocation precoder design

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