Application of MIMO

Spatial multiplexing techniques makes the receivers very complex, and therefore it is typically combined with Orthogonal frequency-division multiplexing (OFDM) or with Orthogonal Frequency Division Multiple Access (OFDMA) modulation, where the problems created by multi-path channel are handled efficiently.

The IEEE 802.16e standard incorporates MIMO-OFDMA. The IEEE 802.11n standard, which is expected to be finalized soon, recommends MIMO-OFDM. MIMO is also planned to be used in Mobile radio telephone standards such as recent 3GPP and 3GPP2 standards.

 In 3GPP, [[HSPA+|High-Speed Packet Access plus (HSPA+)]] and Long Term Evolution (LTE) standards take MIMO into account. Moreover, to fully support cellular environments MIMO research consortia including IST-MASCOT propose to develop advanced MIMO communication techniques such as cross-layer MIMO, multi-user MIMO and ad-hoc MIMO.

Cross-layer MIMO enhances the performance of MIMO links by solving cross-layer problems occurred when the MIMO configuration is employed in the system. Cross-layer techniques has been enhancing the performance of SISO links as well. Examples of cross-layer techniques are Joint source-channel coding, Link adaptation, or adaptive modulation and coding (AMC), Hybrid ARQ (HARQ) and user scheduling.

Multi-user MIMO can exploit multiple user interference powers as a spatial resource at the cost of advanced transmit processing, while conventional, or single-user, MIMO uses only the multiple antenna dimension. Examples of advanced transmit processing for multi-user MIMO are interference aware pre-coding and SDMA-based user scheduling.

Ad-hoc MIMO is a technique useful for future cellular networks which considers Wireless mesh networking or Wireless ad-hoc networking. In wireless ad-hoc networks, multiple transmit nodes communicate with multiple receive nodes. To optimize the capacity of Ad-hoc channels, MIMO concept and techniques can be applied to multiple links between the transmit and receive node clusters. Unlike multiple antennas at the single-user MIMO transceiver, multiple nodes are located as a distributed manner. So, to achieve the capacity of this network, techniques to manage distributed radio resources are essential such as node cooperation and dirty paper coding (DPC) concept based network coding.