Browsing by Author "Zheng, YX"

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A new interleaver design and its application to turbo codes
(2002)
Zheng, YX
;
Su, YT
;
電信工程研究所
;
Institute of Communications Engineering
We present a general interleaver structure that can be systematic derived from any existing block interleaver. When used in a turbo code with proper encoding and decoding procedures, the proposed interleaver is capable of providing unbounded interleaving depth with bounded decoding delay. Given a fixed decoding delay, the new interleaver results in superior bit error rate (BER) performance. The algebraic properties of the associated turbo codes are examined to provide guidelines in design the permutation rule.
Iterative decoding algorithm and terminating criteria for inter-block permuted turbo codes
(2004)
Zheng, YX
;
Su, YT
;
電信工程研究所
;
Institute of Communications Engineering
Inter-block permutation (IBP) concept is a simple but effective technique to improve the performance of a conventional turbo code. On the other hand, proper early termination leads to reduced decoding latency without compromising the performance. For inter-block permuted turbo codes (IBP-TC), however, the termination time variation over blocks within the interleaving span necessitates a new design paradigm. We use both cyclic redundancy check (CRC) code and sign check to make a termination decision and generate soft information for unterminated neighboring blocks at the same time. The new decoder that combines the features of iterative decoding and variable stopping time not only yields less average decoding delay but also outperforms its fixed-stopping-time counterpart by 0.2 - 0.3 dB.
NICE - A decentralized medium access control using neighborhood information classification and estimation for multimedia applications in ad hoc 802.11 wireless LANs
(2003)
Chen, A
;
Wang, LC
;
Su, Y
;
Zheng, YX
;
Yang, B
The desired properties of a medium access control (MAC) protocol in mobile ad hoc network (MANET) include (1) meet quality of service (QoS) requirements for real-time nodes, (2) be decentralized, (3) achieve fairness from viewpoint of throughput or energy consumption, and (4) be immune to the hidden node problem. Though there have been numerous proposed MAC protocols for the IEEE 802.11 WLAN, few of them possesses all of the above four properties. In this paper, we propose a new MAC scheme satisfying all of above four properties. Our protocol can support real-time traffic and satisfy QoS requirements, and can achieve fairness among non-real-time nodes. Also, without using any centralized control, it can be easily deployed in MANET. An analytic model of the protocol's throughput has also been developed. We compare the protocol's throughput obtained from its analytic model and simulation to validate each other.