802.11b wireless LAN enhancement using space-time transmitter beamforming

This paper proposes a method to increase network throughput of the IEEE 802.11b wireless LAN via space-time beamforming at the access point (AP). The physical layer (PHY) design of the mobiles, which are assumed to have single element antennas, is not altered. Based on the Lagrange multiplier interpretation in E. Visotsky et al. (May 1999) of the iterative solution proposed by Rashid-Farrokhi et al. for optimal transmitter beamforming of phase modulated signals (F. Rashid-Farrokhi et al., Oct 1998), a simpler algorithm is obtained by separating the update of the feasible Lagrange multipliers and the corresponding optimal downlink transmit power vector. The algorithm is extended and applied to complementary code keying (CCK), where the information is carried by both phase and (nearly) orthogonal modulation.