A merger of antenna array beam pattern scanning (BPS) and OFDM: achieving directionality and transmit diversity

In this paper, we introduce a novel merger of antenna arrays with moving beam patterns and orthogonal frequency division multiplexing (OFDM) systems. Here, we apply controlled time varying phase shifts to the antenna array elements mounted at the base station. This creates a small movement in the antenna beam pattern that is directed toward the desired user. This beam pattern movement creates a time varying environment and in rich scattering area leads to time diversity exploitable at the receiver. We call this technique beam pattern scanning (BPS) that may create a high probability-of-error performance at the receiver. In this paper, we apply OFDM signals to BPS antenna arrays, and we achieve: 1) directionality, which supports space division multiple access (SDMA); and 2) a time diversity gain, which leads to a high performance. We discuss the structure of the base station antenna array and the OFDM receiver that exploits time diversity and we run probability-of-error performance simulations. These simulations show that a high performance is achievable via BPS/OFDM scheme comparing to traditional OFDM. Simulations with coded OFDM (COFDM) also reveal similar performance improvement through BPS scheme.