Voice services over Adaptive Multiuser Channels on One Slot (VAMOS) is a technology described in the 3GPP GERAN specification that may double the speech capacity in Global System for Mobile Communications (GSM) systems. VAMOS communications generally involve multiplexing a pair of wireless devices served by the same base station on two sub-channels of a single base station radio resource (i.e., physical channel). Benefits of VAMOS include doubling base station transceiver peak capacity, optimizing spectrum utilization, and reducing base station power consumption.
In particular, use of VAMOS channels enables allocating different power levels to wireless devices experiencing different radio conditions, such as where one device is located farther from the base station than the other. However, extra power assigned to one sub-channel occurs at the expense of the other sub-channel. Therefore, VAMOS pairing is optimal when both wireless devices are moving in the same direction and require similar power levels (i.e., at similar distances from the base station). Determining such optimal pairing requires the base station to perform operations that measure and compare real time radio parameters of candidate VAMOS-capable devices, which uses up additional time and resources on the network.