HybridCast: Joint multicast-unicast design for multiuser MIMO networks

Bo Xian Wu, Ching-Ju Lin, Kai Cheng Hsu, Hung Yu Wei

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

5 Scopus citations


Multi-user MIMO (MU-MIMO) has recently been specified in wireless standards, e.g., LTE-Advance and 802.11ac, to allow an access point (AP) to transmit multiple unicast streams simultaneously to different clients. These protocols however have no specific mechanism for multicasting. Existing systems hence simply allow a single multicast transmission, as a result underutilizing the AP's multiple antennas. Even worse, in most of systems, multicast is by default sent at the base rate, wasting a considerable link margin available for delivering extra information. To address this inefficiency, we present the design and implementation of HybridCast, a MU-MIMO system that enables joint unicast and multicast. HybridCast efficiently leverages the unused MIMO capability and link margin to send unicast streams concurrently with a multicast session, while ensuring not to harm the achievable rate of multicasting. We evaluate the performance of HybridCast via both testbed experiments and simulations. The results show that HybridCast always outperforms single multicast transmission. The average throughput gain for 4-antenna AP scenarios is 6.22× and 1.54× when multicast is sent at the base rate and the best rate of the bottleneck receiver, respectively.

Original languageEnglish
Title of host publication2015 IEEE Conference on Computer Communications, IEEE INFOCOM 2015
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages9
ISBN (Electronic)9781479983810
StatePublished - 21 Aug 2015
Event34th IEEE Annual Conference on Computer Communications and Networks, IEEE INFOCOM 2015 - Hong Kong, Hong Kong
Duration: 26 Apr 20151 May 2015

Publication series

NameProceedings - IEEE INFOCOM
ISSN (Print)0743-166X


Conference34th IEEE Annual Conference on Computer Communications and Networks, IEEE INFOCOM 2015
CountryHong Kong
CityHong Kong

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