### Abstract

OFDMA technology can significantly improve the transmission reliability and efficiency because of its inherent frequency diversity and frequency multiplexing. In our recent work [1], we have derived the optimal diversity-multiplexing tradeoff for OFDMA systems under the assumption that each subcarrier occupies the entire coherence bandwidth. However in practical OFDMA systems, such as IEEE 802.16, there are many subcarriers in one coherence bandwidth, i.e., each coherence bandwidth is split into multiple subcarriers which brings the correlation of channel gains among these subcarriers. In this paper, we focus on the diversity-multiplexing tradeoff in this kind of OFDMA systems. First, a correlated random bipartite graph is adopted to formulate this problem. To resolve the user conflicts in subcarrier allocation, the maximum proper f-matching method is introduced to minimize the user outage probability with fairness assurance at given multiplexing gains. Based on this model, the optimal diversity-multiplexing tradeoff curve is obtained. Two extreme points are considered: 1) the full diversity gain is the number of coherence bands, i.e., the same as that in point-to-point OFDM systems; and 2) given a coherence bandwidth, the maximum multiplexing gain is equal to the frequency band equally allocated to each user. The random vertices rotation and extension based Hopcroft-Karp algorithm is then proposed as an optimal subcarrier allocation scheme, which can achieve the optimal tradeoff curve with the time complexity of O S ^{2.5}, where S is the total number of subcarriers.

Original language | English |
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Title of host publication | GLOBECOM 2009 - 2009 IEEE Global Telecommunications Conference |

DOIs | |

Publication status | Published - 2009 |

Externally published | Yes |

Event | 2009 IEEE Global Telecommunications Conference, GLOBECOM 2009 - Honolulu, HI, United States Duration: 30 Nov 2009 → 4 Dec 2009 |

### Other

Other | 2009 IEEE Global Telecommunications Conference, GLOBECOM 2009 |
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Country | United States |

City | Honolulu, HI |

Period | 30/11/09 → 4/12/09 |

### Fingerprint

### ASJC Scopus subject areas

- Electrical and Electronic Engineering

### Cite this

*GLOBECOM 2009 - 2009 IEEE Global Telecommunications Conference*[5425767] https://doi.org/10.1109/GLOCOM.2009.5425767

**Diversity-multiplexing tradeoff in OFDMA systems with coherence bandwidth splitting.** / Bai, Bo; Chen, Wei; Cao, Zhigang; Letaief, Khaled.

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

*GLOBECOM 2009 - 2009 IEEE Global Telecommunications Conference.*, 5425767, 2009 IEEE Global Telecommunications Conference, GLOBECOM 2009, Honolulu, HI, United States, 30/11/09. https://doi.org/10.1109/GLOCOM.2009.5425767

}

TY - GEN

T1 - Diversity-multiplexing tradeoff in OFDMA systems with coherence bandwidth splitting

AU - Bai, Bo

AU - Chen, Wei

AU - Cao, Zhigang

AU - Letaief, Khaled

PY - 2009

Y1 - 2009

N2 - OFDMA technology can significantly improve the transmission reliability and efficiency because of its inherent frequency diversity and frequency multiplexing. In our recent work [1], we have derived the optimal diversity-multiplexing tradeoff for OFDMA systems under the assumption that each subcarrier occupies the entire coherence bandwidth. However in practical OFDMA systems, such as IEEE 802.16, there are many subcarriers in one coherence bandwidth, i.e., each coherence bandwidth is split into multiple subcarriers which brings the correlation of channel gains among these subcarriers. In this paper, we focus on the diversity-multiplexing tradeoff in this kind of OFDMA systems. First, a correlated random bipartite graph is adopted to formulate this problem. To resolve the user conflicts in subcarrier allocation, the maximum proper f-matching method is introduced to minimize the user outage probability with fairness assurance at given multiplexing gains. Based on this model, the optimal diversity-multiplexing tradeoff curve is obtained. Two extreme points are considered: 1) the full diversity gain is the number of coherence bands, i.e., the same as that in point-to-point OFDM systems; and 2) given a coherence bandwidth, the maximum multiplexing gain is equal to the frequency band equally allocated to each user. The random vertices rotation and extension based Hopcroft-Karp algorithm is then proposed as an optimal subcarrier allocation scheme, which can achieve the optimal tradeoff curve with the time complexity of O S 2.5, where S is the total number of subcarriers.

AB - OFDMA technology can significantly improve the transmission reliability and efficiency because of its inherent frequency diversity and frequency multiplexing. In our recent work [1], we have derived the optimal diversity-multiplexing tradeoff for OFDMA systems under the assumption that each subcarrier occupies the entire coherence bandwidth. However in practical OFDMA systems, such as IEEE 802.16, there are many subcarriers in one coherence bandwidth, i.e., each coherence bandwidth is split into multiple subcarriers which brings the correlation of channel gains among these subcarriers. In this paper, we focus on the diversity-multiplexing tradeoff in this kind of OFDMA systems. First, a correlated random bipartite graph is adopted to formulate this problem. To resolve the user conflicts in subcarrier allocation, the maximum proper f-matching method is introduced to minimize the user outage probability with fairness assurance at given multiplexing gains. Based on this model, the optimal diversity-multiplexing tradeoff curve is obtained. Two extreme points are considered: 1) the full diversity gain is the number of coherence bands, i.e., the same as that in point-to-point OFDM systems; and 2) given a coherence bandwidth, the maximum multiplexing gain is equal to the frequency band equally allocated to each user. The random vertices rotation and extension based Hopcroft-Karp algorithm is then proposed as an optimal subcarrier allocation scheme, which can achieve the optimal tradeoff curve with the time complexity of O S 2.5, where S is the total number of subcarriers.

UR - http://www.scopus.com/inward/record.url?scp=77951618993&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77951618993&partnerID=8YFLogxK

U2 - 10.1109/GLOCOM.2009.5425767

DO - 10.1109/GLOCOM.2009.5425767

M3 - Conference contribution

SN - 9781424441488

BT - GLOBECOM 2009 - 2009 IEEE Global Telecommunications Conference

ER -