Capacity Of60GHz Wireless Communication System And Influence Of Capacity By Directivity Of Antenna

60GHz wireless communication is considered as the most promising wirelesscommunication technology in the next10years because of the7GHz bandwidth usedwithout license,10W transmission power and the high transmission rate about severalGbps.The research about the capacity of60GHz wireless communication just starts andonly the capacity of Additive White Gaussian Noise (AWGN) channel is studied atpresent. There are two aims in this paper. One aim is to explore the capacity of fadingchannels and the other aim is to analyze the influence of capacity caused by thedirectivity of antenna. The influence is firstly introduced by this paper whenanalyzing channel capacity up to now.The Nakagami-m channel model is used to research the channel capacity overfading channels. Firstly, the formula of capacity is deduced. Then the capacity issimulated with Matlab. At last, the capacity over Nakagami-m channel model iscompared with the capacity of AWGN channel model. The simulation result showsthat the achievable data rate is3Gbps for a60GHz wireless communication systemwith6GHz bandwidth at a SNR of0dB for BPSK modulation. Compare to thecapacity over AWGN channels, there is1.5Gbps difference which is brought about bythe fading. It is obvious that the capacity decrease over Nakagami-m fading channelsis much greater than the capacity decrease over AWGN channels. It is also concludedthat the longer the communication range, the lower the channel capacity. The60GHzwireless system is more suitable for short range communications less than1km ratherthan long distance. We assume that the other parameters are kept invariant and get thefollowing conclusion: the bigger the m and L, the better the capacity performancebefore achieving the normalized capacity.The CM1and CM2channel model defined by IEEE802.15.3c Task Group are selected to study the influence of capacity caused by the directivity of antenna. Thehalf power beam width (HPBW) of transmitter (Tx) antenna is fixed and the influenceof capacity is discussed by changing the HPBW of Receiver (Rx) antenna. Thefollowing conclusions are obtained. The CM1represents a residential Light-Of-Sight(LOS) environment and the direct path which takes up the most energy of multi-pathis always received by the receiver no matter how to change the HPBW of Rx. Thus,there is nearly no influence caused by the directivity of antenna over CM1. The CM2represents a residential Non-Light-Of-Sight (NLOS) environment. There is no directpath in this model. So there is an obvious influence caused by the directivity ofantenna. In CM2, the wider the HPBW of Rx, the better the capacity performancebefore achieving the normalized capacity.