chapter  22
18 Pages

Multiple-Input Multiple-Output Systems in Wireless Communications

WithSRECO PLEVEL, SASO TOMAŽIČ, TORNAZ JAVORNIK, G. KANDUS

Contents 22.1 Introduction ...........................................................................................438 22.2 Capacity of MIMO Systems ...................................................................439 22.3 Benefits of Multiantenna Systems .......................................................... 442

22.3.1 Array Gain ............................................................................... 442 22.3.2 Interference Reduction ............................................................. 443 22.3.3 Diversity Gain .......................................................................... 443 22.3.4 Multiplexing Gain .....................................................................445

22.4 Space-Time Codes .................................................................................445 22.4.1 Space-Time Trellis Codes .........................................................445 22.4.2 Space-Time Block Codes ......................................................... 446 22.4.3 Alamouti Code ......................................................................... 446

22.5 Spatial Multiplexing ...............................................................................447 22.5.1 Maximum Likelihood Decoding ...............................................447 22.5.2 Matrix Pseudoinversion Decoding ............................................ 448 22.5.3 Successive Interference Cancellation Decoding ........................ 448 22.5.4 Sphere Decoding .......................................................................449

22.1 Introduction Multiple-input multiple-output (MIMO) systems in wireless communications refer to any wireless communication systems in which at both sides of the communication path more than one antenna is used. Systems utilizing multiple transmit and multiple receive antennas are commonly known as MIMO systems. This wireless networking technology greatly improves both the range and the capacity of a wireless communication system. MIMO systems pose new challenges for digital signal processing given that the processing algorithms are becoming more complex, with multiple antennas at both ends of the communication channel. Overviews of MIMO systems can be, found for example, in [1-3].