Coordinated Multi-Point (CoMP) is a Release 11 and beyond feature (formally part of Release 10) that leverages the simultaneous support of multiple transmission points to serve mobile devices in the high interference areas that occur between cells (inter-cell) and between sectors within a given cell (intra-cell).  In theory it can provide stellar gains on the order of
high double-digit percentages for edge of cell user throughput while also
providing at least some increase in overall network efficiency.  In
practical terms, the benefits of CoMP are less clear and there is at least
some justified reservations regarding its potential impact on an operator's
network.

• CoMP 101.  We explain the technical details of the various CoMP
  implementations, including CS/CB, DCS, JT, and uplink, as well the different
  implementation options, namely intra-cell versus inter- cell, and the use of
  distributed baseband pooling versus a distributed approach. 

• The Benefits.  In theory, CoMP can provide a meaningful edge of cell
  performance gain as well as a more modest benefit to overall spectral
  efficiency.  We quantify the potential gains and how they vary based on the
  implementation of CoMP being used, as well as other important assumptions.

• The Challenges.  To varying degrees, the potential benefits of CoMP may not translate from network simulations to real world network deployments.  Multiple technical factors and logistical considerations need to be considered.  We discuss

• The Alternatives.  CoMP isn't the only solution that is capable of increasing spectral efficiency and edge of cell performance.  We discuss what is being done both within the standard (pre-Release 11) and on a vendor-specific basis.

• The Likely Rollout Strategies.  Although recent 3GPP activity has seemingly delayed various aspects of CoMP, it is still a question of when and not if CoMP reaches commercial status.  We explain how we see CoMP being deployed and we examine what some of the vendors are doing to drive higher network performance, either with or without CoMP.
  

In Volume 3 (the LTE edition) and Volume 4 (the HSPA+ edition), we provide our deep-dive analysis of how these technologies perform today as exemplified by operator deployments in North America and Europe. 

By analyzing the performance characteristics of the pertinent infrastructure suppliers (ALU, ERICY, Huawei and NSN), we are able to identify important areas where vendors currently differentiate themselves with respect to their implementation philosophies and the list of features that they currently support.

Areas of focus include frequency selective scheduling, the choice of MIMO (OL-SM versus CL-SM) and the degree to which it is used, the use of 64QAM, and the uplink performance (throughput and transmit power).  Chipset/dongle performance is another important focus area in the report (LTE only).

Finally, we also compare the use of 64QAM in LTE and HSPA+, as well as the use of MIMO at 700MHz versus 2600MHz.