Efficient Broadcasting in Ad Hoc Wireless Networks Using Directional Antennas
IEEE Transactions on Parallel and Distributed Systems
Beam codebook based beamforming protocol for multi-Gbps millimeter-wave WPAN systems
IEEE Journal on Selected Areas in Communications - Special issue on realizing GBPS wireless personal area networks
Ad hoc networking with directional antennas: a complete system solution
IEEE Journal on Selected Areas in Communications
On the potential of fixed-beam 60 GHz network interfaces in mobile devices
PAM'11 Proceedings of the 12th international conference on Passive and active measurement
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A mmWave communication system is equipped with a large number of antennas so as to achieve higher directional gains. Phased array antenna with beam switching is widely-used to minimize the cost of the hardware implementation for the 60 GHz system. An array with beam switching is allowed only to steer at a fixed number of pre-defined angles called beams. However, since devices do not know the locations of other devices a priori, training to obtain the best pair of beams at the transmitter and the receiver is necessary. In this paper, we first present a fast beam training algorithm called beam coding. By coding the beams with directions that are steered simultaneously in a training packet, we are able to obtain the best beam pair out of 32*32 pairs for a 16-antenna system in 2-4 training packets only, independent of traffic load in the network. It outperforms the best existing scheme proposed in IEEE 802.15.3c standard which requires at least 30 packets to complete the full training in a 16-antenna system and is dependent on traffic load. However, two-bit phase quantization is employed in current phase-shifter designs. It distorts the coded beam pattern in our scheme, leading to imprecise beam training in some cases. Enhancements of the scheme can be performed at algorithmic level but increase the burden in the protocol design. Our simulation demonstrates that by implementing 3-bit phase quantization in a 16-antenna system, the SNR loss is reduced from 2 dB to 0.5 dB. In view of this, to support the new protocol, we propose a new approach to architect a higher resolution beamformer. Measurement results show that it can support 7-bit phase quantization level.