Joint Cross-Layer Design for Wireless QoS Content Delivery
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Joint Cross-Layer Design for Wireless QoS Content Delivery Jie Chen Division of Engineering, Brown University, Providence, RI 02912, USA Email: jie [email protected]
Tiejun Lv School of Information Engineering, Beijing University of Posts and Communications, Beijing 100876, China Email: [email protected]
Haitao Zheng Microsoft Research Asia, Sigma Center Beijing, 49 Zhichun Road, Beijing 100080, China Email: [email protected] Received 14 August 2003; Revised 27 June 2004 We propose a joint cross-layer design for wireless quality-of-service (QoS) content delivery. Central to our proposed cross-layer design is the concept of adaptation. Adaptation represents the ability to adjust protocol stacks and applications to respond to channel variations. We focus our cross-layer design especially on the application, media access control (MAC), and physical layers. The network is designed based on our proposed fast frequency-hopping orthogonal frequency division multiplex (OFDM) technique. We also propose a QoS-awareness scheduler and a power adaptation transmission scheme operating at both the base station and mobile sides. The proposed MAC scheduler coordinates the transmissions of an IP base station and mobile nodes. The scheduler also selects appropriate transmission formats and packet priorities for individual users based on current channel conditions and the users’ QoS requirements. The test results show that our cross-layer design provides an excellent framework for wireless QoS content delivery. Keywords and phrases: cross-layer design, wireless QoS, MAC scheduler, power adaptation, frequency-hopping OFDM.
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INTRODUCTION
As mobile cellular networks are evolving to carry voice, video, and data services, an all-Internet protocol- (IP-)based system, including a radio access network and a core network, akin to the Internet, is likely to become the most favorable solution for future wireless Internet-centric systems [1, 2]. The advantages of all-IP networks include cost efficiency, improved reliability, ease of new service implementation, and ease of integration with heterogenous networks. In this paper, we adopt an IP-based network as our cross-layer design platform. With its TCP/IP-based design, the IP network can easily adapt to changing wireless transmission conditions and can offer users a “LAN-like” experience for broadband data and voice services. However, significant difficulties in developing IP-based wireless data networks to meet quality-of-service (QoS) requirements remain and must be addressed. A summary of these difficulties follows.
Dynamic link characteristics Because a mobile device transmits and receives radio signals over the air, wireless transmission is vulnerable to noise and other types of interference. The loss-of-sight effect, multipath fading, and interference from other devices make channel conditions vary unpredictably over time. Changing the transmission rate as a channel varies does improve transmission efficiency but could also result in data rate oscillation. The mobility of handsets
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