Won-Joo Hwang

QoS based MAC protocol for the home network

The home network is one of the most important information infrastructures of the future. Among the home network solutions available, one promising technology is a HomePNA utilizing the phone line. However, it is not able to guarantee the QoS due to the adaptation of the mature IEEE802.3 CSMA/CD technology which is used for Ethernet. In light of this, we propose and evaluate a new MAC protocol for the home network called the HomeMAC that provides guaranteed QoS for appliances and PCs. HomeMAC features a hybrid CSMA/CD-timed token protocol which combines the CSMA/CD with timed token protocol and transmits real-tune traffic based on the QoS level table (QLT) for guaranteeing QoS. In the HomeMAC, there are two different transmission modes, namely, the CSMA/CD mode when there is no real-time traffic, and the timed token mode when there is real-time traffic taking place. By dynamically switching the transmission mode between CSMA/CD mode and timed token mode in accordance with the different kinds of traffic, the hybrid protocol provides low delay, low jitter, and low loss rate to multimedia appliances such as TVs, DVDs, and PCs. Moreover, by providing flexible bandwidth allocation based on QLT, the HomeMAC can serve high QoS whole covering entire offered load.

HomeMAC: QoS-based MAC protocol for the home network

We believe that existing wire solutions such as Home-PNA2.0 and HomePlug and wireless solution such as HomeRF are the most promising solutions, because of its cost-effectiveness. However, MAC protocols of these solutions provide only class of service (CoS) using priority mechanism like HomePNA and HomePlug or consider only voice among real-time traffics like HomeRF For these reasons, we perceive the needs of the new MAC protocol which is no new wire solution and provides guaranteed quality of service (QoS) for not only voice but also video and audio. In light of this, we present the design and software implementation of a new MAC protocol for the home network called the HomeMAC. Our evaluation results of software implementation verify that HomeMAC can provide low delay and low jitter to the real-time traffic by reservation of the bandwidth.

Software implementation of the HomeMAC: QoS based MAC protocol for the home network

In 1999, HomePNA2.0 using phone lines was proposed, and we believe it is one of the most promising solutions, because of its cost-effectiveness. However, owing to the adaptation of the mature IEEE802.3 CSMA/CD technology used for Ethernet, the QoS cannot be guaranteed. In light of this, we present the design, simulation evaluation, software implementation and empirical evaluation of a new MAC protocol for the home network called the HomeMAC. In this paper, the software-based HomeMAC is implemented by programming the kernel space of FreeBSD. The HomeMAC features a hybrid CSMA/CD-timed token protocol, which combines the CSMA/CD for non-real-time traffic with a timed token protocol for real-time traffic. In addition, by providing flexible bandwidth allocation based on a QoS level table (QLT), the HomeMAC can serve high QoS covering the whole offered load. From the results of the evaluation of the software implementation, we verified that HomeMAC can provide low delay, low loss, and low jitter to real-time traffic by reserving bandwidth.

Scalable MPEG video transmission method considering impairments propagation on home network environment

Digitalization of broadcast advances rapidly in Japan since the broadcast satellite (BS) digital broadcast services began in December 2000. It is a requirement that the receiver has a built-in HDD, for storing interesting programs, which may be connected with appliances over the home network. However, it is difficult to guarantee QoS on the home network composed of heterogeneous sub-networks. Therefore, for the purpose of an efficient and appropriate transmission of a video stream such as MPEG over the home network, it is required to develop a new scalable MPEG transmission method. For this reason, we propose a scalability technique considering impairments propagation (SIP), which takes into account the impairments propagated to other frames due to the loss of a macroblock in a given frame. We introduce the SIP technique, evaluate its performance and give a system model using SIP.