Modelling and Optimising TinyTP over IrDA Stacks
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Modelling and Optimising TinyTP over IrDA Stacks A. C. Boucouvalas Microelectronics and Multimedia Communications Research Centre, School of Design, Engineering and Computing, Bournemouth University, Fern Barrow, Poole, Dorset BH12 5BB, UK Email: [email protected]
Pi Huang Microelectronics and Multimedia Communications Research Centre, School of Design, Engineering and Computing, Bournemouth University, Fern Barrow, Poole, Dorset BH12 5BB, UK Email: [email protected] Received 29 March 2004; Revised 20 August 2004 TinyTP is the IrDA transport layer protocol for indoor infrared communications. For the first time, this paper presents a mathematical model for TinyTP over the IrDA protocol stacks taking into account the presence of bit errors. Based on this model, we carry out a comprehensive optimisation study to improve system performance at the transport layer. Four major parameters are optimised for maximum throughput including TinyTP receiver window, IrLAP window and frame size, as well as IrLAP turnaround time. Equations are derived for the optimum IrLAP window and frame sizes. Numerical results show that the system throughput is significantly improved by implementing the optimised parameters. The major contribution of this work is the modelling of TinyTP including the low-layer protocols and optimisation of the overall throughput by appropriate parameter selection. Keywords and phrases: IrDA, TinyTP, IrLAP, transport layer protocol, optimisation.
1.
INTRODUCTION
Indoor infrared data communications, based on the Infrared Data Association (IrDA) standards, have become widely available on a large number of portable devices ranging from mobile phones and digital cameras to laptops and printers [1]. Infrared communication is an excellent choice for effective, inexpensive and high-speed short-range wireless communications. The low-level IrDA protocols including physical (IrPHY) [2, 3], link access (IrLAP) [4], and link management (IrLMP) protocols [5] are adopted as industry standards and implemented on the products. Tiny transport protocol (TinyTP) is an optional IrDA layer, whereas it is so important and widely implemented that it is generally considered a required layer [6]. In [7], an IrLAP model is presented as the first significant work on the IrDA link layer. Subsequently, many link layer performance evaluations and improvements have also been undertaken recently to address different infrared link issues including the impact on link throughput of device processing speed [8] and future increase in data rates [9]. All the previous publications focus on link layer perforThis is an open-access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
mance by assuming data always available of infinite size and a single application ready to transmit. However, upper layers (e.g., TinyTP) in practice offer finite-size packets to the link layer at specific time periods due
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