A cross-layer TCP modelling framework for MIMO wireless systems (original) (raw)

MIMO AND TCP: A CASE FOR CROSS LAYER DESIGN

TCP has notfared well in wireless ad hoc networks. Even in a perfectly static network, there is the problem of throughput degradation due to the interference between flows, which becomes more severe as the nodes come close to each other. Moreover, when two or more TCP flows compete in the same collision domain, often one of the flows "captures " the channel and blocks other flows, giving flows an unfair access to the channel. These problems have been traced in the 802.11 MAC protocol and the interaction between TCP and MAC protocol retransmission timeouts. Proposed solutions range from modifications in the 802.11 MAC protocols to the use of network layer selective drop strategies. However, none of these schemes offers full protection. Moreover, they require change in the existing protocols. The advent of Multiple-Input Multiple-Output (MIMO) system offers a way of increasing total throughput by reducing the interference. The same interference blocking feature leads to unfairness reduction. Recently proposed MIMO MAC protocols such as SPACE-MAC reduce interference by separatingflows. In this paper, we test the efficacy of SPACE-MAC in eliminating the TCP capture problem and reducing throughput degradation due to interference. We evaluate the fairness and throughput performance of SPACE-MAC in various scenarios, and then compare with conventional MAC results via Qualnet simulation.

Physical layer approximations for cross-layer performance analysis in MIMO-BLAST ad hoc networks

IEEE Transactions on Wireless Communications, 2007

In this paper, we consider a MAC protocol for ad hoc networks where nodes are equipped with multiple antennas, and communications are spatially multiplexed using the Bell labs LAyered Space Time (BLAST) system. The contribution of this paper is twofold. First, we introduce two different analytical models aimed at predicting the propagation of detection errors within the BLAST receiver, the first based on a Gaussian approximation of the detection errors, and the second on the weighed enumeration of error configurations. A simplification of the latter, with lower complexity, is also obtained and compared to the original model. We then use these analytical tools to assess the performance of a cross-layer MAC protocol, and compare it with fully detailed simulations. Since the analytical tools replace the simulation of the physical layer, the proposed semianalytical approach is much faster than the bit-by-bit simulations. Numerous results are provided for the network performance assessment, showing that our semianalytical approach is able to predict network behavior with very good accuracy, but much lower complexity.

Cross-Layer Protocols for Multimedia Communications over Wireless Networks

Book Chapter in Advanced Communication Protocol Technologies: Solutions, Methods and Applications, Editors: Katalin Tarnay, Guzstav Adamis and Tibor Dulai, Chapter No: 15, pp. 318 – 354, ISBN: 978-1-60960-732-6, IGI-Global Publishers, USA, 2010, 2010

In the last few years, the Internet throughput, usage, and reliability have increased almost exponentially. The introduction of broadband wireless mobile ad hoc networks (MANETs) and cellular networks, together with increased computational power, have opened the door for a new breed of applications to be created; namely, real-time multimedia applications. Delivering real-time multimedia traffic over a complex network like the Internet is a particularly challenging task since these applications have strict quality-of-service (QoS) requirements on bandwidth, delay, and delay jitter. Traditional Internet protocol (IP)-based best effort service is not able to meet these stringent requirements. The time-varying nature of wireless channels and resource constrained wireless devices make the problem even more difficult. To improve perceived media quality by end users over wireless Internet, QoS supports can be addressed in different layers, including application layer, transport layer, and link layer. Cross layer design is a well-known approach to achieve this adaptation. In cross-layer design, the challenges from the physical wireless medium and the QoS-demands from the applications are taken into account so that the rate, power, and coding at the physical (PHY) layer can be adapted to meet the requirements of the applications given the current channel and network conditions. A number of propositions for cross-layer designs exist in the literature. In this chapter, an extensive review has been made on these cross-layer architectures that combine the application-layer, transport layer, and the link layer controls. Particularly, issues like channel estimation techniques, adaptive controls at the application and link layers for energy efficiency, priority based scheduling, transmission rate control at the transport layer, and adaptive automatic repeat request (ARQ) are discussed in detail.

Enhancing the capabilities of MIMO by properly designing higher layer protocols

Improving the MIMO capabilities at different layers has been the focus of many research efforts. In this report, we address the problem of setting the upper bound on TCP congestion window limit (CWL) with MIMO at the physical layer. The idea that this report present is, how the performance of MAC layer can be improved, with MIMO at the physical layer. And how the TCP CWL can be adjusted with modified MAC in order to improve the TCP layer performance.

Cross-layer modeling of wireless channels for data-link and IP layer performance evaluation

Computer Communications, 2006

To provide a tool for performance evaluation of IP-based delay-and loss-sensitive applications running over wireless channels we propose a novel cross-layer wireless channel modeling approach. We firstly develop simple and computationally efficient wireless channel modeling algorithm. For this purpose we adopt the special solution of the inverse eigenvalue problem and show that its complexity significantly decreases when the time-series is covariance stationary two-valued in nature. Our model explicitly takes into account autocorrelation and distributional properties of empirical data. Then, we extend this model to IP layer using the cross-layer mappings. The resulting model is represented by the IP packet error process and reflects memory properties of initial bit error process. We show that our approach allows to get accurate estimators of IP packet error probabilities in presence of FEC at the data-link layer eliminating the need for computationally expensive time-consuming bit level simulations. It also provides a way to choose the required correction capabilities of FEC codes resulting in best possible performance at the data-link and IP layers. q

MIMO Network and the Alamouti, STBC (Space Time Block Coding

In the present world, the spectrum efficiency along with the capacity and coverage of wireless networks are being improved by wireless specialists. Wireless link performance could be enhanced and improved by using multiple antenna technology called Space time wireless technology. There exists some advancement in the present MIMO techniques which could further improve the overall wireless Local Area Network (LANs) and Wide Area Network (WANs). In Multipath fading performance gain is very important which could be achieved by using an efficient Space-Time Coding (STC) technique. This Space Time coding along with Alamouti Scheme is a very vibrant research topic. In the forthcoming generation of mobile communication there will be a need of high data rate, reliable communication link and vast multimedia capabilities, STBC is the one solution for these. This paper presents the Space-Time Block Codes (STBC) for wireless networks using Alamouti Scheme in which multiple antennas are being used at both transmitter and receiver. The simulations have been done in MATLAB.

Cross-Layer Analytical Modeling of Wireless Channels for Accurate Performance Evaluation

2004

An intention to adopt IP protocol for future mobile communication and subsequent extension of Internet services to the air interface calls for advanced performance modeling approaches. To provide a tool for accurate performance evaluation of IP-based applications running over the wireless channels we propose a novel cross-layer wireless channel modeling approach. We extend the small-scale propagation model representing the received signal strength to IP layer using the cross-layer mappings. Proposed model is represented by the IP packet error process and retains memory properties of initial signal strength process. Contrarily to those approaches developed to date, our model requires less restrictive assumptions regarding behavior of the small-scale propagation model at layers above physical. We compare results obtained using our model with those, published to date, and show that our approach allows to get more accurate estimators of IP packet error probabilities.