Linear precoding for capacity maximization in MU-MIMO BC channels

Amara, Mustapha

Multiuser MIMO (MU-MIMO) downlink system known in the information theory as the broadcast channel system is one of the most importantly investigated subjects in wireless communications. This important interest comes from the high potential it offers in improving reliability and throughput of the system and the problem starts to be considered in recent systems such as LTE, WiFi, . . .

               Actually, as there is a non linear correlation between directions and as, furthermore, the power allocation are coupled, the sum rate, i.e. the cost function to maximize, is a non convex function; Nevertheless, Information theory has shown that the capacity of BC could be achieved through dirty-paper coding (DPC). Considering the complexity and resource consumption of DPC, some suboptimal linear algorithms have been proposed. Among them we can find the iterative and the closed form solutions.
The practical, precoder design techniques can also be differentiated according to the number of streams allowed per user. In fact, some of them can only support at maximum one stream per user even if the system is not fully charged. Some multi-stream precoding solutions have lately been proposed. Nevertheless, they present some drawbacks as some impose the number of streams per user and thus does not perform a stream selection to optimize the system sum-rate (SR) and some convergence problems towards some local maximum are limiting the throughput.
This thesis outlines our attempt to propose some optimization algorithms for linear precoding in multiuser MIMO downlink scheme. It is essentially a collection of the following: Linear precoding for MU-MIMO BC with single stream support. Linear precoding for MU-MIMO BC with multiple stream per user selection.

Systèmes de Communication
Eurecom Ref:
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