A 60 GHz radio is an attractive technology in wireless home networks because it can provide high data rate up to a few Gbps. A 60 GHz network generally uses directional antennas and has a problem of neighbor discovery even though it has an advantage of high data transmissions. In particular, if a directional antenna is used in self-organized wireless adhoc networks, the neighbor discovery time and energy consumption can be significantly increased. To solve this problem, we propose a multi-band directional neighbor discovery scheme, in which management procedures are carried out by using the 2.4 GHz band with the omni-directional antennas whereas data transmissions are performed by using the 60 GHz band with directional antennas. Analytical models on the neighbor discovery time and energy consumption are also derived by considering assisted and beamforming periods in the neighbor discovery procedure through the omni-directional antenna and directional antenna. Performance evaluation results demonstrate that the proposed scheme outperforms comparative schemes that use only directional beamforming in terms of the average neighbor discovery time and energy consumption.Index Terms-Directional antennas, mmWave ad-hoc networks, multi-band application, neighbor discovery, selforganization.0018-9545 (c)
International audienceQuality of Experience (QoE) is the key to success for multimedia applications and perceptual video quality is one of the important component of QoE. A recent video encoding scheme called Scalable Video Coding (SVC) provides the flexibility and the capability to adapt the video quality to varying network conditions and heterogeneous users. In this paper, we focus on SVC multicast over IEEE 802.11 networks. Traditionally, multicast uses the lowest modulation resulting in a video with only base quality even for users with good channel conditions. To optimize QoE, we propose to use multiple multicast sessions with different transmission rates for different SVC layers. The goal is to provide at least the multicast session with acceptable quality to users with bad channel conditions and to provide additional multicast sessions having SVC enhancement layers to users with better channel conditions. The selection of modulation rate for each SVC layer and for each multicast session is achieved with binary integer linear programming depending on network conditions with a goal to maximize global QoE. Results show that our algorithm maximizes global QoE by providing highest quality videos to users with good channel conditions and by guaranteeing at least acceptable QoE for all users
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.