Beacon pack

STEM technologies have the ability to spread information to those corners of the world where Internet access has yet to reach. However, there are very few technologies that can bring this necessity to developing countries, most of which do not have the capital to pursue these technologies. In this paper, we discuss Beacon Pack, a solar powered database in a travelers pack that can bring information acquired from the Internet to these individuals in developing countries with low-level cellular phones or feature phones. Our product tackles this issue of providing this info, specifically news articles, to developing countries through an existing cellular signal. Beacon Pack connects to any cell signal and can thus provide educational content to surrounding individuals through SMS text, one of the few communication tools that most third world citizens have access to today. We found that this project is not only incredibly beneficial, but it is also pragmatic in its approach to bridging the information gap. Through simple coding techniques, our team was able to establish this technology to support multiple users at a cost of $150 per pack. Each pack, when connected to a single cellular service signal, can supply thousands of users with information in the area, making this project highly cost efficient. Consequently, we plan for this device to be expanded into outside countries by a San Jose based non-profit, Community Technology Alliance. Through their efforts, more teams of engineers will be able to further implement Beacon Pack to include several different types of educational tools for users, all of which will be SMS text enabled

A control theoretic approach to achieve proportional fairness in 802.11e EDCA WLANs

This paper considers proportional fairness amongst ACs in an EDCA WLAN for provision of distinct QoS requirements and priority parameters. A detailed theoretical analysis is provided to derive the optimal station attempt probability which leads to a proportional fair allocation of station throughputs. The desirable fairness can be achieved using a centralised adaptive control approach. This approach is based on multivariable statespace control theory and uses the Linear Quadratic Integral (LQI) controller to periodically update CWmin till the optimal fair point of operation. Performance evaluation demonstrates that the control approach has high accuracy performance and fast convergence speed for general network scenarios. To our knowledge this might be the first time that a closed-loop control system is designed for EDCA WLANs to achieve proportional fairness

Control-theoretic approaches for efficient transmission on IEEE 802.11e wireless networks

With the increasing use of multimedia applications on the wireless network, the functionalities of the IEEE 802.11 WLAN was extended to allow traffic differentiation so that priority traffic gets quicker service time depending on their Quality of Service (QoS) requirements. The extended functionalities contained in the IEEE Medium Access Control (MAC) and Physical Layer (PHY) Specifications, i.e. the IEEE 802.11e specifications, are recommended values for channel access parameters along traffic lines and the channel access parameters are: the Minimum Contention Window CWmin, Maximum Contention Window CWmax, Arbitration inter-frame space number, (AIFSN) and the Transmission Opportunity (TXOP). These default Enhanced Distributed Channel Access (EDCA) contention values used by each traffic type in accessing the wireless medium are only recommended values which could be adjusted or changed based on the condition of number of associated nodes on the network. In particular, we focus on the Contention Window (CW) parameter and it has been shown that when the number of nodes on the network is small, a smaller value of CWmin should be used for channel access in order to avoid underutilization of channel time and when the number of associated nodes is large, a larger value of CWmin should be used in order to avoid large collisions and retransmissions on the network. Fortunately, allowance was made for these default values to be adjusted or changed but the challenge has been in designing an algorithm that constantly and automatically tunes the CWmin value so that the Access Point (AP) gives out the right CWmin value to be used on the WLAN and this value should be derived based on the level of activity experienced on the network or predefined QoS constraints while considering the dynamic nature of the WLAN. In this thesis, we propose the use of feedback based control and we design a controller for wireless medium access. The controller will give an output which will be the EDCA CWmin value to be used by contending stations/nodes in accessing the medium and this value will be based on current WLAN conditions. We propose the use of feedback control due to its established mathematical concepts particularly for single-input-single-output systems and multi-variable systems which are scenarios that apply to the WLAN