Physical limits on directional beam performance of 28 GHz links
13 November 2017
Impact of finite coherence in frequency and time on directional beam in a canonical 28 GHz small cell link is assessed. Terminal motion and delay spread are found to limit the maximum achievable directional gain due to the need to measure the channel across time and frequency. It is found that pedestrian speeds (1m/s) still allow 1 Gbps rate at 100 m in Non-Line-of-Sight (25 dB shadow) link using 32 array elements in 300 MHz bandwidth, nearly 10x the rate of a 10 MHz-wide cellular link at 2 GHz. Vehicular speed of 30 m/s requires nearly 2x the element count to reach the same rate.