Performance of TCP/RLP protocol stack on correlated fading DS-CDMA wireless links

In this paper, we present the throughput performance of the transport control protocol/radio link protocol (TCP/RLP) stack on correlated fading direct-sequence code-division multiple-access (DS-CDMA) wireless links. It is shown that because of significant burstiness in RLP frame errors in highly correlated Rayleigh fading, longer persistence at the RLP layer to recover lost RLP frames (more than the IS-99 specified three retransmission attempts at the RCP layer) is beneficial at low-link fading margins

Performance of TCP/RLP protocol stack on correlated fading DS-CDMA wireless links

We present the throughput performance of Transport Control Protocol/Radio Link Protocol (TCP/RLP) stack on correlated fading direct sequence code division multiple access (DS-CDMA) wireless links. It is shown that, because of significant burstiness in the RLP frame errors in highly correlated Rayleigh fading, longer persistence at the RLP layer to recover lost RLP frames (more than the IS-99 specified 3 retransmission attempts at the RLP layer) is beneficial at low link fading margins

Differential Radio Link Protocol: An Improvement To Tcp Over Wireless Networks

New generations of wireless cellular networks, including 3G and 4G technologies, are envisaged to support more mobile users and a variety of wireless multimedia services. With an increasing demand for wireless multimedia services, the performance of TCP becomes a bottleneck as it cannot differentiate between the losses due to the nature of air as a medium and high data load on the network that leads to congestion. This misinterpretation by TCP leads to a reduction in the congestion window size thereby resulting in reduced throughput of the system. To overcome this scenario Radio Link Protocols are used at a lower layer which hides from TCP the channel related losses and effectively increases the throughput. This thesis proposes enhancements to the radio link protocol that works underneath TCP by identifying decisive frames and categorizing them as {\em crucial} and {\em non-crucial}. The fact that initial frames from the same upper layer segment can afford a few trials of retransmissions and the later frames cannot, motivates this work. The frames are treated differentially with respect to FEC coding and ARQ schemes. Specific cases of FEC and ARQ strategies are then considered and it is shown qualitatively as how the differential treatment of frames can improve the performance of the RLP and in effect that of TCP over wireless networks

Low complexity channel models for approximating flat Rayleigh fading in network simulations

The intricate dependency of networking protocols upon the performance of the wireless channel motivates the investigation of network channel approximations for fading channels. Wireless networking protocols are increasingly being designed and evaluated with the assistance of networking simulators. While evaluating networking protocols such as medium access control, routing, and reliable transport, the network channel model, and its associated capacity, will drastically impact the achievable network throughput. Researcher relying upon simulation results must therefore use extreme caution to ensure the use of similar channel models when performing protocol comparisons. Some channel approximations have been created to mimic the behavior of a fading environment, however there exists little to no justification for these channel approximations. This dissertation addresses the need for a computationally efficient fading channel approximation for use in network simulations. A rigorous flat fading channel model was developed for use in accuracy measurements of channel approximations. The popular two-state Markov model channel approximation is analyzed and shown to perform poorly for low to moderate signal-to-noise ratios (SNR). Three novel channel approximations are derived, with multiple methods of parameter estimation. Each model is analyzed for both statistical performance and network performance. The final model is shown to achieve very accurate network throughput performance by achieving a very close matching of the frame run distributions. This work provides a rigorous evaluation of the popular two-state Markov model, and three novel low complexity channel models in both statistical accuracy and network throughput performance. The novel models are formed through attempts to match key statistical parameters of frame error run and good frame run statistics. It is shown that only matching key parameters is insufficient to achieve an acceptable channel approximation and that it is necessary to approximate the distribution of frame error duration and good frame run duration. The final novel channel approximation, the three-state run-length model, is shown to achieve a good approximation of the desired distributions when some key statistical parameters are matched

Adaptive network abstraction layer packetization for low bit rate H.264/AVC video transmission over wireless mobile networks under cross layer optimization

Master'sMASTER OF ENGINEERIN

Avaliação da estrategia ARQ hibrido na interação entre os protocolos TCP e RLP sobre sistemas celulares CDMA

Orientador: Renato Baldini FilhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de ComputaçãoMestradoTelecomunicações e TelemáticaMestre em Engenharia Elétric