Optimal transmission scheme for a distributed antenna in CDMA system

F Tong, I A Glover, S R Pennock, P R Shepherd

Research output: Contribution to conferencePaper


Distributed antenna diversity employs separately installed, but cooperating, antennas within a single base-station; it has been proved that the uplink capacity (per cell) in terms of maximum achievable SIR (signal-to-interference ratio) is linear with the number of deployed antenna units. While in the downlink, because of the multiple-to-one propagation topology, equal power (transmission power at each antenna) allocation (providing equal SIR) in the base-station results in fixed SIR at the mobile terminal, irrespective of the number of base-station antennas used. A transmission scheme, using optimal power allocation and SIR-balanced power control, is proposed to increase the SIR by exploiting multiple base-station antennas. The downlink diversity (called antenna-multipath diversity) transfers the antenna diversity to multipath diversity by utilizing the spread-spectrum signal property. If optimal, rather than equal, power allocation is employed with antenna-multipath diversity, the SDMA advantage can be exploited. The optimisation result shows that, for a particular user, transmitting a signal from one antenna, instead of all base-station antennas, gives better SIR performance. The SIR CDF has been examined by simulation to verify this scheme. Compared to sending from all antennas, the result shows, that for 8 users, this scheme yields improved SIR by 3 dB with 5 antennas. The SIR advantage increases with increasing numbers of antennas and decreases, however, with increasing numbers of users in the cell.
Original languageEnglish
Number of pages4
Publication statusPublished - 2004
Event5th IEE International Conference on 3G Mobile Communication Technologies (3G 2004) - London
Duration: 18 Oct 200420 Oct 2004


Conference5th IEE International Conference on 3G Mobile Communication Technologies (3G 2004)


  • spread spectrum communication
  • equal power allocation
  • downlink diversity
  • multipath channels
  • diversity reception
  • telecommunication control
  • SIR-balanced power control
  • antenna-multipath diversity
  • SDMA
  • uplink capacity
  • spread-spectrum signal
  • multiple base-station antennas
  • signal-to-interference ratio
  • distributed antenna diversity
  • mobile radio
  • power control
  • code division multiple access
  • CDMA


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