LTE, LTE-Advanced and WiMAX: Towards IMT-Advanced Networks

Coordinated Multi-Point (CoMP) Transmission

The performance of cell-edge users is known to be interference-limited. This has been an unavoidable situation for all previous generations due to the inherent per-cell processing. In other words, since a MS can be only affiliated with one BS at a time, except for the duration of the soft handover process, cell-edge users will be prone to interference from neighboring cells. Consequently, their SINR will be reduced in proportion to the interference level, which directly lowers their achievable capacity. This has been traditionally dealt with by proper resource management between neighboring cells, for example, fractional FR.

Figure 2.11 DL and UL CoMP techniques.

A radical shift in this cell-centric processing has been recently made through CoMP techniques [11]. CoMP refers to a family of techniques through which the UL and/or the DL transmissions can be simultaneously managed by multiple neighboring BSs as shown in Figure 2.11.

In doing so, CoMP aims at exploiting rather than mitigating inter-cell interference, hence forming a distributed multiple antenna system. By coordinating and combining signals from multiple BSs, CoMP makes it possible for MSs to enjoy consistent performance and QoS when they access and share videos, photos and other high-bandwidth services regardless of their remoteness from the BS. Hence, CoMP techniques improve ...