| 1. |
- Leanderson, Carl Fredrik, et al.
(författare)
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List sequence MAP decoding
- 2002
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Ingår i: Conference Record / IEEE Global Telecommunications Conference. ; 2, s. 1037-1041
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Konferensbidrag (refereegranskat)abstract
- A list sequence (LS) maximum a posteriori probability (MAP) decoding algorithm for convolutional codes, that takes into account bitwise a priori probabilities and produces a rank ordered list of [script L] sequence MAP estimates, can be obtained by modification of the metric increments of the serial list Viterbi algorithm. In this paper, we study the performance of LS-MAP decoding with genie-assisted error detection on the additive white Gaussian noise channel. Computer simulations and approximate analytical expressions, based on geometrical considerations are presented. We focus on the frame error rate and it is concluded that LS-MAP decoding with [script L] > 1 often exploits a priori information more efficiently than conventional single sequence MAP decoding ( [script L] = 1). This leads in many cases to larger relative gains with LS-MAP than LS-ML decoding as [script L] increases.
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| 2. |
- Leanderson, Carl Fredrik, et al.
(författare)
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Simultaneous soft symbol and list sequence decoding
- 2002
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Ingår i: IEEE International Symposium on Information Theory - Proceedings. - 0780375017 ; , s. 287-287
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Konferensbidrag (refereegranskat)abstract
- A soft output decoding algorithm for convolutional codes, yielding list sequence (LS) decoding and soft symbol output was presented. The max-log list algorithm (MLLA) was introduced, it provides near-optimum soft symbol output equal to that of the max-log MAP algorithm. It was shown that the suboptimum MLLA provides the performance-complexity tradeoff.
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| 3. |
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| 4. |
- Leanderson, Carl Fredrik, et al.
(författare)
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Joint source-channel list sequence decoding
- 2002
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Ingår i: 13th IEEE International Symposium on Personal Indoor and Mobile Radio Communications. PIMRC 2002. Proceedings (Cat. No.02TH8637). - 0780375890 ; , s. 951-955
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Konferensbidrag (refereegranskat)abstract
- We evaluate the performance of list sequence (LS) maximum a posteriori probability (MAP) decoding on the additive white Gaussian noise (AWGN) channel and the fully interleaved flat Rayleigh fading channel. In particular, we focus on the frame error rate (FER) of LS-MAP decoding with genie-assisted error detection. It is demonstrated that LS-MAP decoding yields significant performance improvements relative to single sequence MAP decoding on the AWGN channel as well as the fully interleaved flat Rayleigh fading channel. Furthermore, feedback convolutional codes have been observed to have the potential to yield improved FER performance with both single sequence MAP and IS-MAP decoding, compared to feedforward convolutional codes. Based on these performance improvements, we propose a joint source-channel IS decoding scheme. The scheme is based on the max-log list algorithm for simultaneous soft symbol and IS decoding of convolutional codes. In existing systems where a cyclic redundancy check for error mitigation is concatenated with a convolutional code for error correction, this scheme can be implemented in a fully backward compatible receiver
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| 5. |
- Leanderson, Carl Fredrik
(författare)
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On the Design of Error Control Coding for Wireless Communication Systems
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- New wireless services such as mobile Internet, multimedia streaming and high speed packet data access are making their way to the market. Availability of low-cost equipment providing high transmission quality and efficient spectrum utilization is crucial to the success of these services. This thesis is a collection of papers that address an important step in this direction: efficient error control coding, with high flexibility and low complexity. In particular, we discuss the design of codes, decoders and incremental redundancy transmission that can provide increased throughput in systems based on convolutional and parallel concatenated Turbo codes. Papers I to IV deal with low-rate Turbo codes for code-division multiple-access systems. It is demonstrated that super-orthogonal Turbo codes can achieve better error performance than maximum free distance convolutional codes at low signal-to-noise ratios on the additive white Gaussian noise (AWGN) channel. Design criteria for low-rate Turbo codes that result in performance improvements compared to the super-orthogonal Turbo codes are presented. Termination techniques are studied and it is concluded that no termination of either component encoder causes severe performance degradation, while the differences are small between the other investigated termination strategies. Papers V and VI evaluate the performance of incremental redundancy transmission over the block-fading Gaussian collision channel. For low channel loads, binary convolutional codes give throughput performance close to the achievable limits with binary signaling, while, at high channel loads, significant throughput gains are to be obtained by improved coding strategies such as Turbo coding and adaptation of modulation order and code rate to the channel conditions. Papers VII to X address list sequence decoding in concatenated systems with an outer error detecting code and an inner error correcting code. An efficient low-complexity algorithm that provides both soft symbol output and a list of decoded sequences, ranked in order of a posteriori probability, is presented and applied to joint source-channel and Turbo decoding. Analytical error performance expressions for list sequence decoding with genie-assisted error detection on the AWGN and flat Rayleigh fading channels are provided. Significant performance gains are at hand with list sequence decoding relative to single sequence decoding in future systems, or, with backward compatibility, in existing systems.
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