TY - JOUR
T1 - Constructions of DMT optimal vector codes for asynchronous cooperative networks using decode-and-forward protocols
AU - Lu, Francis
PY - 2010/7/1
Y1 - 2010/7/1
N2 - An asynchronous cooperative network where different time delays exist among nodes is considered in this paper. Assuming the signals are OFDM modulated, it is first shown that the diversity-multiplexing tradeoff (DMT) achieved by the non-orthogonal selection decode-and-forward (NSDF) protocol for this network is the same as that for the synchronous one. In contrast to the complicated approximately universal "matrix" codes, where each relay uses a different codebook, a systematic construction of an extremely simple "vector" code is proposed. Given the transmitted codeword vector, this vector will be used by all nodes in the network for signal transmission; hence, the proposed coding scheme greatly reduces the complexity of relay deployment and decoding. Furthermore, it is proven that the proposed scheme is optimal in terms of the DMT of the NSDF protocol for this asynchronous network, provided all time delays are distinct. Finally, it is shown that the proposed code design can be extended to the orthogonal selection decode-and-forward protocol and remains to be DMT optimal.
AB - An asynchronous cooperative network where different time delays exist among nodes is considered in this paper. Assuming the signals are OFDM modulated, it is first shown that the diversity-multiplexing tradeoff (DMT) achieved by the non-orthogonal selection decode-and-forward (NSDF) protocol for this network is the same as that for the synchronous one. In contrast to the complicated approximately universal "matrix" codes, where each relay uses a different codebook, a systematic construction of an extremely simple "vector" code is proposed. Given the transmitted codeword vector, this vector will be used by all nodes in the network for signal transmission; hence, the proposed coding scheme greatly reduces the complexity of relay deployment and decoding. Furthermore, it is proven that the proposed scheme is optimal in terms of the DMT of the NSDF protocol for this asynchronous network, provided all time delays are distinct. Finally, it is shown that the proposed code design can be extended to the orthogonal selection decode-and-forward protocol and remains to be DMT optimal.
KW - Asynchronous cooperative network
KW - cyclic division algebra
KW - decode-and-forward protocol
KW - diversity-multiplexing gain tradeoff
KW - multi-block space-time code
UR - http://www.scopus.com/inward/record.url?scp=77954712328&partnerID=8YFLogxK
U2 - 10.1109/TWC.2010.07.100002
DO - 10.1109/TWC.2010.07.100002
M3 - Article
AN - SCOPUS:77954712328
VL - 9
SP - 2392
EP - 2400
JO - IEEE Transactions on Wireless Communications
JF - IEEE Transactions on Wireless Communications
SN - 1536-1276
IS - 7
M1 - 5508989
ER -