LTE Advanced: 3GPP Solution for IMT-Advanced

13.5 Uplink CoMP Reception

As opposed to downlink, uplink CoMP reception is simpler from a 3GPP specification point of view. Uplink CoMP can be applied already for Release 8 UEs as uplink CoMP does not necessarily require any changes to the radio specifications. Naturally, the actual implementation of uplink CoMP requires changes on the network side. CoMP reception requires that the signals from several antennas in the network are routed to a central baseband receiver, where they can be combined and used in the detection process for every user. Joint reception techniques may be combined with other uplink enhancement techniques such as Interference Rejection Combining (IRC), adaptive antennas and multi-user detection schemes.

As uplink CoMP reception can be done with no negative impact to system capacity in general, it is an attractive technique up to the point where it is too expensive to route the sampled signals via transport or to handle the additional computational complexity in the receiver. As such, the intra-site LTE CoMP is similar to softer handover in WCDMA. Intra-site CoMP sets no requirements for the transport. But uplink CoMP reception may also be done across a large set of cells when the baseband hotel model is applied, see the previous section.

There is a myriad of uplink CoMP techniques [2], each presenting a different compromise of performance gains, transport data rate and latency, as well as computational complexity. Some of the possible uplink CoMP techniques ...