User Influence on MIMO Channel Capacity for Handsets in Data Mode Operation

The current paper concerns realistic evaluation of the capacity of the MIMO channel between a BS and handheld device, such as a PDA or smartphone, held in front of the user's body (data mode). The work is based on measurements of the MIMO channel between two widely separated BSs in a micro-cellular setup, and six handsets located in an indoor environment. The measurements are done simultaneously in both the 773.5-778.5 MHz and 2250-2350 MHz bands, and from the two BSs. The handsets are realistic types and were measured both in free space and with twelve different users, using both one and two hands. The random capacities of the channels are evaluated in terms of outage capacity. For an SNR of 10 dB, median capacities in free space of about 4.4-4.7 bit/s/Hz for the low band and about 3.3-3.8 bit/s/Hz for the high band were found. The mean decrease in outage capacity due to the user was found to be up to about 2.2 bit/s/Hz, depending on the band and handset. More results are presented in the paper.