Md. K. Hasan et al.: A Middleware Based Network Hot Swapping Solution for SCA Compliant Radio Contributed Paper Manuscript received July 15, 2009 0098 3063/09/$20.00 © 2009 IEEE 1315 A Middleware Based Network Hot Swapping Solution for SCA Compliant Radio Md. Kamrul Hasan, Lenin Mehedy, Muhammad Salim Zabir, Sungyoung Lee, Young-Koo Lee Abstract — Software Communication Architecture (SCA) provides a framework for developing Software Defined Radios (SDR). Theoretically, SCA compliant SDRs are supposed to have the capability of self-configuring and switching from one wireless protocol to any other. However, conventional SDRs running standard upper layer protocol stack fail to switch wireless protocols on the fly retaining all the connections and incur large delay. In this paper, we propose a mechanism for wireless protocol switching that is free from these problems. We base our approach on dual or multiple antennas operable by SDR software. The main contribution of this paper is the Hot Swapping Middleware (HSM) that ensures seamless switching between wireless protocols without affecting the application performance. HSM manages IP addressing issues transparently and ensures in order delivery of data packets without loss. Our proposal is free from any requirement of infrastructure support, light weight and easily SCA component upgradeable. Simulation results show that our proposal improves the total data transfer of applications in an SDR by more than 25%. We also have developed a proof-of-concept prototype 1 . Index Terms — Software Radio, SCA, Hot Swapping Middleware, Middleware. I. INTRODUCTION With the expansion of different wireless networking technologies, Software Defined Radio (SDR) has been gaining increasing attention in recent years. JTRS has played a pivotal role in the process through their standard Software Communication Architecture (SCA). SCA provides a framework for developing Software Defined Radios (SDR). Theoretically, SCA compliant SDRs are supposed to have the 1 This research was supported by Ministry of Knowledge Economy, Korea, under ITRC program supervised by Institute of Information Technology Advancement (IITA-2009-C1090-0902-0002). This work was also supported by KOSEF grant funded by the Korean government (MEST, No. 2008-1342), and was supported by Basic Science Research Program funded by National Research Foundation (2009-0076798). Md. Kamrul Hasan is with Ubiquitous Computing Lab, Kyung Hee University, South Korea. (email: kamrul@oslab.khu.ac.kr ) Lenin Mehedy is with University of Melbourne, Australia. (email: leninmehedy@yahoo.com ) Muhammad Salim Zabir is with Kyushu University, Japan. (email: szabir@yahoo.com ) Sungyoung Lee is with Ubiquitous Computing Lab, Department of Computer Engineering, Kyung Hee University, South Korea. (email: sylee@oslab.khu.ac.kr ). Prof. Sungyoung Lee is the Corresponding Author. Young-Koo Lee is with Department of Computer Engineering, Kyung Hee University, South Korea. (email: yklee@khu.ac.kr ) capability of self-configuring and switching from one wireless protocol to another [1]-[7]. However, conventional SDRs running standard upper layer protocol stack like TCP/IP, fail to switch wireless protocol on the fly without affecting the application performance. Usually, each wireless protocol switch involves a change in the IP address of the SDR device unless both wireless access points and base stations belong to the same network. A change in the IP address results in a discontinuation of traditional connection oriented protocols like TCP. This problem may be solved by Mobile IP [12], [13] or USHA [11] at the cost of infrastructure requirement and large hand off latency. Also, their adoption causes data loss due to large handoff latency. Infrastructure requirement is expensive and difficult to deploy in practice. On the other hand, large handoff latency causes data loss which ultimately leads to degradation in Quality of Service (QoS) as experienced by the application. In this paper, we therefore propose a mechanism of network switching for SCA compliant SDR which overcomes the above problems [15]. That is, our proposal ensures replacement of wireless network protocol or network switching without affecting an SDR’s operation. This essentially complies with the definition of hot swapping or hot plugging in general. Therefore, we name our proposal as network hot swapping. At the base of our approach lies dual or multiple antennas operable by different SDR software. The main contribution of this paper is the Hot Swapping Middleware (HSM) that ensures seamless switching between wireless protocols without affecting the application performance. Hot swapping means plug ability of hardware or re configurability and upgradeability of the software components. Software hot swap infrastructure provides an auto-managed mechanism to reconfigure or upgrade software, component wise, in such a way that the operation of the whole software is not interrupted. It is highly desirable that the downtime to be zero or near to zero. Software radio brings a band of waveform from antenna and processes that in software [1]-[7]. Because of the software processing, it is possible to reconfigure a software radio for many different wave forms. It is easily possible to configure a handheld to be a GSM handset or a WLAN receiver. But current software radios cannot do network switching on the fly, retaining all the connections. The radio turns off network activities, configures itself for a different protocol and then starts working again. Although, some similar efforts are found in the literature in the name of vertical hand off [8]-[13] for Authorized licensed use limited to: KYUNGHEE UNIVERSITY. Downloaded on November 3, 2009 at 20:14 from IEEE Xplore. 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