Cost-aware downlink scheduling of shared channels for cellular networks with relays

Challa, N.; Çam, Hasan

doi:10.1109/pccc.2004.1395186

Cited by 12 publications

(3 citation statements)

References 9 publications

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“…Relays: Several works [8,9,7] have investigated the potential of relay-enabled wireless networks to provide improved coverage and capacity. Scheduling of unicast data has received higher emphasis [9,8,5,7,6] thus far in these networks.…”

Section: Related Workmentioning

confidence: 99%

“…Scheduling of unicast data has received higher emphasis [9,8,5,7,6] thus far in these networks. Most of the earlier works [9,8] focused on TDMA variants where the scheduling decision reduces mainly to deciding whether to employ a relay or not and for which particular user. They do not exploit multiple OFDM channels and the resulting diversity available across the relay and access hops.…”

Section: Related Workmentioning

confidence: 99%

“…However, some of the channels may be fractionally shared between sessions in each component, whose integrality needs to be restored for a feasible schedule. For each component c, we determine the loss due to integrality restoration (steps [4][5][6][7][8][9][10][11][12]. This requires a new integral channel allocation (Z k,c ) for each component c. With A * k as the maximum flow Z k,c = 0, ∀k, i and B k = A * k , ∀k.…”

Section: Lp-based Algorithm: Lsdpmentioning

confidence: 99%

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Cooperation vs. multiplexing

Sundaresan¹,

Rangarajan²

2010

Proceedings of the Eleventh ACM International Symposium on Mobile Ad Hoc Networking and Computing

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With the next generation cellular networks making a transition towards smaller cells, two-hop OFDMA relay networks have become a dominant, mandatory component in the 4G standards (WiMAX 802.16j, 3GPP LTE-Adv). While unicast flows have received reasonable attention in two-hop OFDMA relay networks, not much light has been shed on the design of efficient scheduling algorithms for multicast flows, thereby forming the focus of this work. We show that while relay cooperation is critical for improving multicast performance, it must be carefully balanced with the ability to multiplex multicast sessions and hence maximize aggregate multicast flow. To this end, we highlight strategies that carefully group relays for cooperation to achieve this balance. We then solve the multicast scheduling problem under two OFDMA sub-channelization models. We establish the NP-hardness of the scheduling problem even for the simpler model and provide efficient algorithms with approximation guarantees under both models. Evaluation of the proposed solutions reveals the efficiency of the scheduling algorithms as well as the significant benefits obtained from the multicasting strategy.

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Section: Related Workmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

Section: Lp-based Algorithm: Lsdpmentioning

confidence: 99%

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Cooperation vs. multiplexing

Sundaresan¹,

Rangarajan²

2010

Proceedings of the Eleventh ACM International Symposium on Mobile Ad Hoc Networking and Computing

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On coexistence of unicast and multicast traffic in relay-enabled wireless networks

Sundaresan¹,

Rangarajan²

2008

2008 5th International Conference on Broadband Communications, Networks and Systems

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Relay-enabled wireless networks (eg. WIMAX 802.16j) coupled with orthogonal frequency division multiple access (OFDMA) as the air interface technology represent an emerging trend in future wireless infrastructure deployments. While the Bexibility of OFDMA allows accommodation of heterogeneous (unicast and multicast) traffic, its combination with relays opens up a multitude of diversity and spatial reuse gains. However, leveraging these benefits to efficiently handle heterogeneous traffic calls for more sophisticated solutions, among which, user scheduling forms a key component.We ask the following specific question in this work: Can unicast and multicast traffic efficiently coexist in an OFDMAbased wireless relay network? We address the question by first identifying the key challenges that make coexistence difficult in the target environment. We show that scheduling of unicast and multicast traffic is tightly coupled even if they are isolated through orthogonal spectral allocations. We also show that the nature of gains that optimize the individual traffic are complementary and hence reveal a fundamental tradeoff in jointly optimizing the system for both unicast and multicast traffic in tandem. Using the insights gained, we propose an integrated scheduling strategy that strikes a good balance in delivering efficient performance to both the unicast and multicast Bows. The proposed solution yields gains of over 60% over individual traffic specific strategies.

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