Optimized constellations for two-way wireless relaying with physical network coding

We investigate modulation schemes optimized for two-way wireless relaying systems, for which network coding is employed at the physical layer. We consider network coding based on denoise-and-forward (DNF) protocol, which consists of two stages: multiple access (MA) stage, where two terminals transmit simultaneously towards a relay, and broadcast (BC) stage, where the relay transmits towards the both terminals. We introduce a design principle of modulation and network coding, considering the superposed constellations during the MA stage. For the case of QPSK modulations at the MA stage, we show that QPSK constellations with an exclusive-or (XOR) network coding do not always offer the best transmission for the BC stage, and that there are several channel conditions in which unconventional 5-ary constellations lead to a better throughput performance. Through the use of sphere packing, we optimize the constellation for such an irregular network coding. We further discuss the design issue of the modulation in the case when the relay exploits diversity receptions such as multiple-antenna diversity and path diversity in frequency-selective fading. In addition, we apply our design strategy to a relaying system using higher-level modulations of 16QAM in the MA stage. Performance evaluations confirm that the proposed scheme can significantly improve end-to-end throughput for two-way relaying systems.

[1]  Toshiaki Koike-Akino,et al.  Denoising Maps and Constellations for Wireless Network Coding in Two-Way Relaying Systems , 2008, IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference.

[2]  M. Zorzi,et al.  Network Coding meets MIMO , 2008, 2008 Fourth Workshop on Network Coding, Theory and Applications.

[3]  Michael Gastpar,et al.  Computation Over Multiple-Access Channels , 2007, IEEE Transactions on Information Theory.

[4]  RankovBoris,et al.  Spectral efficient protocols for half-duplex fading relay channels , 2007 .

[5]  Soung Chang Liew,et al.  Hot topic: physical-layer network coding , 2006, MobiCom '06.

[6]  Niklas Johansson,et al.  Coded Bi-directional Relaying , 2006, 2006 IEEE 63rd Vehicular Technology Conference.

[7]  Yunnan Wu,et al.  Information Exchange in Wireless Networks with Network Coding and Physical-layer Broadcast , 2004 .

[8]  Patrick Mitran.  The diversity-multiplexing tradeoff for independent parallel MIMO channels , 2008, 2008 IEEE International Symposium on Information Theory.

[9]  Petar Popovski,et al.  Bi-directional Amplification of Throughput in a Wireless Multi-Hop Network , 2006, 2006 IEEE 63rd Vehicular Technology Conference.

[10]  W. Fischer,et al.  Sphere Packings, Lattices and Groups , 1990 .

[11]  Sachin Katti,et al.  Embracing wireless interference: analog network coding , 2007, SIGCOMM '07.

[12]  Thomas M. Cover,et al.  Elements of Information Theory , 2005 .

[13]  Toshiaki Koike-Akino,et al.  Denoising Strategy for Convolutionally-Coded Bidirectional Relaying , 2009, 2009 IEEE International Conference on Communications.

[14]  Sang Joon Kim,et al.  Comparison of bi-directional relaying protocols , 2008, 2008 IEEE Sarnoff Symposium.

[15]  Alexander Sprintson,et al.  Joint Physical Layer Coding and Network Coding for Bidirectional Relaying , 2008, IEEE Transactions on Information Theory.

[16]  Petar Popovski,et al.  The Anti-Packets Can Increase the Achievable Throughput of a Wireless Multi-Hop Network , 2006, 2006 IEEE International Conference on Communications.

[17]  Thomas M. Cover,et al.  Elements of Information Theory: Cover/Elements of Information Theory, Second Edition , 2005 .

[18]  Sachin Katti,et al.  The Importance of Being Opportunistic: Practical Network Coding for Wireless Environments , 2005 .

[19]  Armin Wittneben,et al.  Spectral efficient protocols for half-duplex fading relay channels , 2007, IEEE Journal on Selected Areas in Communications.

[20]  Petar Popovski,et al.  Physical Network Coding in Two-Way Wireless Relay Channels , 2007, 2007 IEEE International Conference on Communications.

[21]  Tobias J. Oechtering,et al.  Broadcast Capacity Region of Two-Phase Bidirectional Relaying , 2007, IEEE Transactions on Information Theory.

[22]  Armin Wittneben,et al.  Achievable Rate Regions for the Two-way Relay Channel , 2006, 2006 IEEE International Symposium on Information Theory.

[23]  Patrick Mitran,et al.  Performance Bounds for Bidirectional Coded Cooperation Protocols , 2007, IEEE Transactions on Information Theory.

[24]  Rudolf Ahlswede,et al.  Network information flow , 2000, IEEE Trans. Inf. Theory.

[25]  Soung Chang Liew,et al.  > Replace This Line with Your Paper Identification Number (double-click Here to Edit) < 1 , 2022 .

[26]  Muriel Médard,et al.  XORs in the Air: Practical Wireless Network Coding , 2006, IEEE/ACM Transactions on Networking.