Software radio architecture with smart antennas: A tutorial on algorithms and complexity

Recently, there has been considerable interest in using antenna arrays in w ireless communication networks to increase the capacity and decrease the co channel interference. Adaptive beamforming with smart antennas at the recei ver increases the carrier-to-interference ratio (CIR) in a wireless link, T his paper considers a wireless network with beamforming capabilities at the receiver which allows two or more transmitters to share the same channel t o communicate with the base station. The concrete computational complexity and algorithm structure of a base station are considered in terms of a soft ware radio system model, initially with an omnidirectional antenna. The sof tware radio computational model is then expanded to characterize a network with smart antennas, The application of the software radio smart antenna is demonstrated through two examples. First, traffic improvement in a network with a smart antenna is considered, and the implementation of a hand-off a lgorithm in the software radio is presented. The blocking probabilities of the calls and total carried traffic in the system under different traffic p olicies are derived. The analytical and numerical results show that adaptiv e beamforming at the receiver reduces the probability of blocking and force d termination of the calls and increases the total carried traffic in the s ystem. Then, a joint beamforming and power control algorithm is implemented in a software radio smart antenna in a CDMA network. This shows that, by u sing smart antennas, each user can transmit with much lower power, and ther efore the system capacity increases significantly.