| In the wireless communication system, data compression is one of themain technologies for source encoding, which aims to represent the signalsfrom the source with lease digits so as to improve the effectiveness ofcommunication. Therefore, study of data compress technology is of greatsignificance to the modern communication system.Digital microwave GRRU (GSM Digital Remote RF Units) is a newtype of wireless network coverage pattern. With the advancing of networkintegration, the traditional GRRU system will have to handle more types andlarger volumes of data, while the transmission capacity of current digitalmicrowave transmission system is limited. Therefore, it is necessary to studythe application of data compression technology in GRRU system.Based on above backgrounds, this paper first discussed the basicprinciples of data compression and approaches to realize it from theperspective of the information theory. Then by analyzing and comparing different typical data compression algorithms, it determines predictivecoding is feasible for data compression of GRRU system. The papercontinues to study the ADPCM (Adaptive Differential Pulse CodeModulation) and DPCM (Differential Pulse Code Modulation) on thetheoretical level, and offers improvement of the adaptive quantization inADPCM algorithms. Theoretic simulations are made on above algorithmswith CMSK modulating signal acting as the source, whose results suggestthis algorithms works better for GRRU system. Last, algorithms of datacompression and decompression are realized in digital medium frequencyplate of GSM16frequency-selecting. Index including delay, dynamic rangeand EVM(Error Vector Magnitude) are measured and results shows theperformance of system would decline to some extent when the functions ofdata compress and decompression are added, but could remain within theallowable range. So this algorithm has some perspective in GRRU system,which can dramatically increase the transmission capacity of GRRU system. |
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