Many antennas


Many antennas is a smart antenna technique which overcomes the performance limitation of single user multiple-input multiple-output techniques. In cellular communication, the maximum number of considered antennas for downlink is 2 and 4 to support 3GPP Long Term Evolution and IMT Advanced requirements, respectively. Since the available spectrum band will probably be limited while the data rate requirement will continuously increase beyond IMT-A to support the mobile multimedia services, it is highly probable that the number of transmit antennas at the base station must be increased to 8–64 or more. The installation of many antennas at single base stations introduced many challenges and required development of several high technologies: a new SDMA engine, a new beamforming algorithm and a new antenna array.
The table summarizes the recent history of multiple antenna techniques in cellular communications. The table includes the future prediction as well for IMT-A and beyond.
StandardsWCDMAHSDPALTEIMT Advanced
Deployment2003200620122015
Peak rate 384 k14 M100–320 M1 G
Bandwidth 552040–100
Tx antennas in a macro-cell222–44–8
ParadigmReliabilityData ratePeak rateAverage rate
Spatial processingSpatial diversity: circuitSpatial diversity: packetSpatial multiplexing Spatial division