The emerging 60-GHz multigigabits per second wireless technology enables the streaming of high-quality “uncompressed” video, which has been impossible with other existing wireless technologies. To support such a resource-hungry uncompressed video streaming service with limited wireless resources, it is necessary to design efficient link adaptation policies selecting suitable transmission rates for the 60-GHz wireless channel environment, thus optimizing video quality and resource management. For proper design of the link adaptation policies, we propose a new metric, called expected peak signal-to-noise ratio (ePSNR), to numerically estimate the video streaming quality. By using the ePSNR as a criterion, we propose two link adaptation policies with different objectives considering unequal error protection (UEP). The proposed link adaptation policies attempt to 1) maximize the video quality for given wireless resources, or 2) minimize the required wireless resources, while meeting the video quality. From the link adaptation policies, we provide a distributed resource management scheme for multiple users to maintain satisfactory video streaming quality. Our extensive simulation results demonstrate that the newly proposed variable, i.e., ePSNR, well represents the level of video quality. It is also shown that the proposed link adaptation policies can enhance the resource efficiency while achieving acceptable quality of the video streaming.

Today, voice over IP (VoIP) service is emerging as a popular and important application in wireless local area networks (WLANs). While rate adaptation (or link adaptation) has been identified as a key factor determining the performance of WLANs, we have observed that most (if not all) rate adaptation algorithms have been developed to improve the throughput of data traffic, not the quality of service (QoS) of VoIP traffic. Accordingly, in this paper, we investigate the characteristics of VoIP traffic and the limitations of state-of-the-art rate adaptation algorithms, and then enhance the QoS of voice over WLAN (VoWLAN) by ameliorating the existing rate adaptation algorithms. Specifically, we design fast decrease to control the transmission rate of retransmissions, and retry scheduling to avoid the deep fading of the wireless channel as well as hidden terminal interference. We comparatively evaluate the QoS of the revised rate adaptation algorithms via ns-3 simulations and MadWiFi implementations in various communication environments, and demonstrate that the proposed schemes improve the R-score performance by up to 80 percent depending on the network scenarios.

Voice over IP (VoIP) service is emerging as a popular application in wireless local area networks (WLANs). However, the existing rate adaptation (or link adaptation) schemes for WLANs have been developed to improve the throughput of data traffic, not the quality of service (QoS) of VoIP traffic. In this paper, we investigate the characteristics of VoIP traffic and the limitations of state-of-the-art rate adaptation schemes, and then enhance the QoS of voice over WLANs (VoWLANs) by ameliorating the existing rate adaptation schemes. Specifically, we design fast decrease to control the transmission rate of retransmissions, and retry scheduling to avoid the deep fading of the wireless channel as well as hidden terminal interference. We comparatively evaluate the QoS of the revised rate adaptation schemes via ns-3 simulations and MadWiFi implementations in various communication environments, and demonstrate that the proposed scheme improves the R-score performance by up to 80% depending on the network scenarios.