March 2011
Intermediate
680 pages
25h 12m
English
Chapter 15
Multilevel Coding Theory
15.1 Introduction
In wireless communications, bandwidth has always been a precious resource. However, the entire suite of high-definition multimedia services increasingly requires real-time or low-latency, high-rate transmissions. The aforementioned demanding multimedia applications require reliable, high-integrity transmissions as well as the error-free transmission of certain important data, which leads to the requirement of creating FEC schemes exhibiting an Unequal Error Protection (UEP) capability.
An attractive technique for increasing the achievable data rate without increasing the associated bandwidth or symbol rate is constituted by the employment of coded modulation. The concept of MultiLevel Coding (MLC) was proposed by Imai and Hirakawa [81] as a powerful bandwidth efficient coded modulation technique using several component codes in conjunction with employing appropriate bit-to-symbol mapping strategies. The component codes employed are typically binary codes, which have different rates and error correcting capabilities. The rationale of this coding technique is that of increasing the achievable Euclidean distance between the legitimate encoded sequences. This enables code designers to adjust the associated distance properties in order to meet the target performance. Due to the employment of different-rate component codes, MLC facilitates the flexible adjustment of the effective coding rate for meeting the specifications of diverse ...
