An Adaptive HARQ Scheme for Cooperative Communication

Autor: Chih-Chiang Hsu, 徐志強
Rok vydání: 2010
Druh dokumentu: 學位論文 ; thesis
Popis: 98
The recent rapid growth in consumer electronic products, e.g. smart phone, notebook, has led to the great deal of demands for mobile commerce and multimedia entertainment. Also, transmit rate and quality become more and more importance. Hence, in order to achieve such demands, maximum transmit rate and reliable quality are very importance issue. For solving above problem, error control is the most adopted scheme. There are two basic error control schemes, namely Automatic Repeat Request (ARQ) and Forward Error Correction (FEC), applying in wireless communication, extensively. For achieving higher throughput, HARQ scheme combines FEC and ARQ technologies. The other solution to enhance performance is cooperative communication, which increases system throughput utilizing spatial diversity by cooperating with relay station. The throughput for HARQ schemes applying in cooperative communication system are investigated in this paper. Then, we analyze their advantage and disadvantage, and compute the suitable using time by switching each other. Further, for representing the Channel Quality Indicator (CQI), this paper proposes one kind of K factor based on Rician fading. Then, according to this K factor, we can adaptive switch these HARQ schemes. The computer simulation confirms that these scheme can achieve maximum throughput under suitable error rate. In addition, to lower power of handhold devises, this paper proposes an improved Type-III HARQ. For reducing the complexity of Type-III HARQ, under given CQI, there are two technologies can be chosen. One is decoding the package directly, but when the result of the decoded package is error, the retransmitted package would be combined with pre-package, then decoding again. The other is directly combined with pre-package and then decoding. Then, the simulation results show that at lower SNR and K factor, this improved Type-III HARQ can provide higher throughput than Type-II HARQ. Then, according to this advantage of reducing complexity, i.e.it lower decoding times, Type-III HARQ can lower power of handhold devises.
Databáze: Networked Digital Library of Theses & Dissertations
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