WiderCast: Enabling Wider Bandwidth for Wireless Multicast Over IEEE 802.11ac WLANs

A wide bandwidth through the channel bonding of IEEE 802.11ac significantly increases the capacity of wireless transmissions. However, multicast traffic is simply transmitted using a narrow 20 MHz bandwidth because the access point (AP) is agnostic to the supportable bandwidth information of clients in a multicast group. This paper proposes WiderCast which enables channel bonding for multicast in IEEE 802.11ac WLANs. In WiderCast, the AP scales the bandwidth for multicast transmissions according to the supportable bandwidths of multicast clients. To enable bandwidth negotiation between the AP and clients without high control overhead, WiderCast employs a novel bandwidth signaling scheme, in which multicast clients can simultaneously deliver their supportable bandwidth information to the AP without collision. We verified the feasibility of WiderCast with a prototype on software-defined radio. We also conducted an extensive simulation study demonstrating that WiderCast achieves higher throughput and improved video quality than traditional wireless multicast. To the best of our knowledge, this is the first work to take into account channel bonding for wireless multicast in WLANs.