Software radio architecture with smart antennas: a tutorial onalgorithms and complexity

摘要

There has been considerable interest in using antenna arrays innwireless communication networks to increase the capacity and decreasenthe cochannel interference. Adaptive beamforming with smart antennas atnthe receiver increases the carrier-to-interference ratio (CIR) in anwireless link. This paper considers a wireless network with beamformingncapabilities at the receiver which allows two or more transmitters tonshare the same channel to communicate with the base station. Thenconcrete computational complexity and algorithm structure of a basenstation are considered in terms of a software radio system model,ninitially with an omnidirectional antenna. The software radioncomputational model is then expanded to characterize a network withnsmart antennas. The application of the software radio smart antenna isndemonstrated through two examples. First, traffic improvement in annetwork with a smart antenna is considered, and the implementation of anhand-off algorithm in the software radio is presented. The blockingnprobabilities of the calls and total carried traffic in the system underndifferent traffic policies are derived. The analytical and numericalnresults show that adaptive beamforming at the receiver reduces thenprobability of blocking and forced termination of the calls andnincreases the total carried traffic in the system. Then, a jointnbeamforming and power control algorithm is implemented in a softwarenradio smart antenna in a CDMA network. This shows that, by using smartnantennas, each user can transmit with much lower power, and thereforenthe system capacity increases significantly