Robust wireless video multicast using distributed antennas-based IEEE 802.11n infrastructure

Abstract

Wireless Video Multicast is prone to suffer from frequent packet losses, resulting from the fact that the IEEE 802.11 standard does not use any mechanisms such as Acknowledgements and retransmissions, to combat the errors that are common in the dynamic wireless medium. However this paper shows that the infrastructure can be adapted to reduce the wireless errors, by using spatial diversity and spatial expansion to combat the wireless medium's random nature. This is obtained by adding a number of antennas placed equidistantly at the edge of the coverage area, using the same total transmit power that would be used with one transmit antenna. Moreover, this paper shows that since the IEEE 802.11n, the standard which facilitates the use of multiple antennas, states that the maximum number of antennas at any transceiver is four, two Access Points can be used to transmit the same data packet in orthogonal time slots to transmit good quality H.264 video resulting in all nodes experiencing an average Peak Signal to Noise Ratio greater than 36dB for MCS-5 and MCS-6 for a coverage area having radius of 60m. Since only two time slots are used, these results are obtained with a ½ code rate which is an improvement to the code rate used in current cooperative schemes.