On analysis and design of low density generator matrix codes for continuous phase modulation
2007 (English)In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 6, no 9, 3440-3449 p.Article in journal (Refereed) Published
We investigate the analysis and design of low density generator matrix (LDGM) codes for continuous phase modulation (CPM). The system uses LDGM codes as an outer code for CPM. For additive white Gaussian noise channels, we derive the union bound to analyze the error floor performance. Design principles for lowering error floors are suggested from this analysis. We propose a design approach of jointly considering the LDGM code degree and the CPM modulation index. Then we consider the rate-adaptive system for slowly fading channels. By changing the rate of the LDGM codes, the information rate of the CPM signals is adapted according to channel variations. We use a low-rate LDGM code as the mother code. Higher rates are achieved by puncturing the output of these codes. To exploit the rate-flexible property of punctured LDGM codes, a rate function is proposed to calculate the rate of each transmitted block. Thus, we can have a quasi-continuous information rate. Numerical results show that this approach can improve the energy efficiency from a discrete-rate adaptation. Using the rate-daptive approach, up to 11 dB transmitted energy gain can be achieved from the non-adaptive scheme in the low bit-error-rate region (smaller than 10(-3)) for minimum shift keying (MSK).
Place, publisher, year, edition, pages
2007. Vol. 6, no 9, 3440-3449 p.
continuous phase modulation, low density generator matrix codes, rate-adaptive, slowly fading, union bound
Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-45818DOI: 10.1109/TWC.2007.06020051ISI: 000249309000039OAI: oai:DiVA.org:kth-45818DiVA: diva2:453027
QC 201111022011-10-312011-10-312012-03-22Bibliographically approved