### Abstract

The computational complexity of a sphere decoder (SD) is conventionally reduced by decoding the order scheme which sorts candidate symbols in the ascending order of the Euclidean distance from the soft-output signal points of a zero-forcing (ZF) receiver. However, since the soft-output signal point of ZF may not be a reliable sorting reference, we propose two types of sorting schemes to allow faster decoding. The first is to use the newly found lattice points in the previous search round instead of the ZF solution (Type I). Since these lattice points are closer to the received signal than the ZF solution, they can serve as a more reliable sorting reference for finding the maximum likelihood (ML) solution. The second sorting scheme is to sort candidate symbols in descending order according to the number of candidate symbols in the following layer, which are called child symbols (Type II). These two proposed sorting schemes can be combined with layer sorting for more complexity reduction. Through simulation, the Type I and Type II sorting schemes were found to provide 12% and 20% complexity reduction respectively over conventional sorting schemes. When they are combined with layer sorting, Type I and Type II provide an additional 10-15% complexity reduction while maintaining detection performance.

Original language | English |
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Title of host publication | Proceedings - CIS Workshops 2007, 2007 International Conference on Computational Intelligence and Security Workshops, CISW 2007 |

Pages | 80-84 |

Number of pages | 5 |

Volume | 1 |

Publication status | Published - 2007 Dec 1 |

Event | 2007 International Conference on Future Generation Communication and Networking, FGCN 2007 - Jeju Island, Korea, Republic of Duration: 2007 Dec 6 → 2007 Dec 8 |

### Other

Other | 2007 International Conference on Future Generation Communication and Networking, FGCN 2007 |
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Country | Korea, Republic of |

City | Jeju Island |

Period | 07/12/6 → 07/12/8 |

### Fingerprint

### All Science Journal Classification (ASJC) codes

- Computer Science Applications
- Software
- Electrical and Electronic Engineering

### Cite this

*Proceedings - CIS Workshops 2007, 2007 International Conference on Computational Intelligence and Security Workshops, CISW 2007*(Vol. 1, pp. 80-84). [4426098]

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*Proceedings - CIS Workshops 2007, 2007 International Conference on Computational Intelligence and Security Workshops, CISW 2007.*vol. 1, 4426098, pp. 80-84, 2007 International Conference on Future Generation Communication and Networking, FGCN 2007, Jeju Island, Korea, Republic of, 07/12/6.

**Two new types of candidate symbol sorting schemes for complexity reduction of a sphere decoder.** / Eun, Sung Jeon; Yo, Han Kim; Dong, Ku Kim.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

TY - GEN

T1 - Two new types of candidate symbol sorting schemes for complexity reduction of a sphere decoder

AU - Eun, Sung Jeon

AU - Yo, Han Kim

AU - Dong, Ku Kim

PY - 2007/12/1

Y1 - 2007/12/1

N2 - The computational complexity of a sphere decoder (SD) is conventionally reduced by decoding the order scheme which sorts candidate symbols in the ascending order of the Euclidean distance from the soft-output signal points of a zero-forcing (ZF) receiver. However, since the soft-output signal point of ZF may not be a reliable sorting reference, we propose two types of sorting schemes to allow faster decoding. The first is to use the newly found lattice points in the previous search round instead of the ZF solution (Type I). Since these lattice points are closer to the received signal than the ZF solution, they can serve as a more reliable sorting reference for finding the maximum likelihood (ML) solution. The second sorting scheme is to sort candidate symbols in descending order according to the number of candidate symbols in the following layer, which are called child symbols (Type II). These two proposed sorting schemes can be combined with layer sorting for more complexity reduction. Through simulation, the Type I and Type II sorting schemes were found to provide 12% and 20% complexity reduction respectively over conventional sorting schemes. When they are combined with layer sorting, Type I and Type II provide an additional 10-15% complexity reduction while maintaining detection performance.

AB - The computational complexity of a sphere decoder (SD) is conventionally reduced by decoding the order scheme which sorts candidate symbols in the ascending order of the Euclidean distance from the soft-output signal points of a zero-forcing (ZF) receiver. However, since the soft-output signal point of ZF may not be a reliable sorting reference, we propose two types of sorting schemes to allow faster decoding. The first is to use the newly found lattice points in the previous search round instead of the ZF solution (Type I). Since these lattice points are closer to the received signal than the ZF solution, they can serve as a more reliable sorting reference for finding the maximum likelihood (ML) solution. The second sorting scheme is to sort candidate symbols in descending order according to the number of candidate symbols in the following layer, which are called child symbols (Type II). These two proposed sorting schemes can be combined with layer sorting for more complexity reduction. Through simulation, the Type I and Type II sorting schemes were found to provide 12% and 20% complexity reduction respectively over conventional sorting schemes. When they are combined with layer sorting, Type I and Type II provide an additional 10-15% complexity reduction while maintaining detection performance.

UR - http://www.scopus.com/inward/record.url?scp=52249087816&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=52249087816&partnerID=8YFLogxK

M3 - Conference contribution

SN - 0769530486

SN - 9780769530482

VL - 1

SP - 80

EP - 84

BT - Proceedings - CIS Workshops 2007, 2007 International Conference on Computational Intelligence and Security Workshops, CISW 2007

ER -