MERGING OSCILLATING-BEAM SMART ANTENNA ARRAYS AND WIDEBAND MULTI-CARRIER CDMA: EXPLOITING TRANSMIT DIVERSITY, FREQUENCY DIVERSITY AND DIRECTIONALITY

摘要

In this paper, a novel merger of wideband MC-CDMA (multi-carrier code division multiple access) and smart antenna arrays is introduced. Here, each group of Q carriers in the MC-CDMA system is applied to its own M-element smart antenna array at the base station (BS). The smart antennas are located in close proximity to one another. We generate a transmit diversity gain at the receiver by carefully moving (oscillating) the antenna array's pattern. This is achieved by applying appropriate time-varying phases to array elements of each smart antenna. The beam pattern oscillation generates a mainlobe at the position of the intended user and small oscillations in the beam pattern. This beam pattern oscillation leads to a time varying channel with a controllable coherence time; hence, a transmit diversity benefit, in the form of a time diversity benefit, is available at the receiver. Employing MC-CDMA with the proposed smart antenna at the BS, we achieve: 1) directionality which creates high network capacity via space division multiple access (SDMA); 2) a transmit diversity gain which supports high performance at the receiver in the mobile unit; and 3) increased capacity and performance via MC-CDMA's ability to support both code division multiple access and frequency diversity benefits respectively.