Abstract
A general framework is developed for multi-source cooperation (MSC) protocols to improve diversity and spectral efficiency relative to repetition based alternatives that rely on single-source cooperation. The novel protocols are flexible to balance tradeoffs among diversity, spectral efficiency and decoding-complexity. Users are grouped in clusters and follow a two-phase MSC protocol which involves time division multiple access (TDMA) to separate users within a cluster, and code division multiple access (CDMA) used to separate clusters. An attractive protocol under the general MSC framework relies on distributed complex field coding (DCFC) to enable diversity order equal to the number of users per cluster. Cluster separation based on orthonormal spreading sequences leads to spectral efficiency 1/2. When the number of clusters exceeds the amount of spreading, spectral efficiency can be enhanced without sacrificing diversity, at the expense of controllable increase in complexity. Simulations corroborate our analytical claims.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 415-425 |
| Number of pages | 11 |
| Journal | IEEE Journal on Selected Areas in Communications |
| Volume | 25 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 2007 |
Bibliographical note
Funding Information:Manuscript received February 6, 2006; revised July 12, 2006. Part of the results in this paper appeared in [10]. This work was prepared through collaborative participation in the Communications and Networks Consortium sponsored by the U. S. Army Research Laboratory under the Collaborative Technology Alliance Program, Cooperative Agreement DAAD19-01-2-0011. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon.
Keywords
- Complex field coding
- Diversity methods
- Multiaccess communication
- User cooperation