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Wlan Power Save with offset Listen Interval for Machine to Machine Communications

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M2M communication networks have the cost and energy efficiency problem of the embedded devices. Wireless LAN power save mechanism is designed to experience the performance degradation and also unbalanced energy consumptions in the human communication systems. An analytical model takes into account for a different network architecture and traffic patterns of the communication between the machines. And, the model ensures the high contention and long packet delay found during the process of packet forwarding in the network. To minimize the performance drop, a new algorithm called Offset Listen Interval (OLi) is proposed which enriches the existing power save mechanism and increases the life time of communication networks. The algorithm extends the traffic occurred in the M2M systems with calculated offset to improve the network contention and to reduce packet delay. OLI defines energy efficiency and compares it with the standard power save mechanism. The Orthogonal Frequency Division Multiplexing (OFDM) algorithm is proposed that requires only one received OFDM block and it belongs to the category of one-shot estimation method.
M2M communication is different from current Human-to-Machine (H2M) and Human-to-Human (H2H) communication models in that it involves new or different market scenarios, low cost, low power, low effort, a potentially very large number of communication terminals, and infrequent data transmissions per terminal. The current wireless networks are mainly designed for H2M and H2H communication modes based on mobility and human interactive requirements such as c all setup, handover, and quality of service (QoS). Since M2M communications bring very different network structure, devices, traffic patterns, and performance requirements, there are urgent needs to enhance the wireless access networks for M2M communications. In fact, there are potential issues of high contention and unbalanced power consumption that may hinder large scale deployment of M2M communication networks. In a M2M communication network, there can be a large number of STAs associated with one AP. The traffic from these STAs includes sensor/meter readings in the uplink and actuation/control messages in the downlink. This traffic is expected to be light and periodic with a predefined ListenInterval in the order of minutes. When the ListenIntervals of a number of STAs are aligned, i.e. they wake up in the same beacon period to poll the AP, high collision may arise even when the overall network traffic load is low. The process result shows that the network collision probability and packet delay can be as high as 30% and 16 ms, when there are 15 stations polling in one beacon period.
Analytical model is to characterize the power save performance of contention based M2M communication networks with large numbers of devices and periodic traffic. The model predicts the collision probability and packet delay of a M2M communication device. Analysis results show high collision probability and long delay associated with M2M PS devices, while traditional traffic models under estimate such measures. Algorithm is used that spreads the M2M traffic evenly across WLAN beacon periods with calculated offsets to alleviate network contention and reduce packet delay. The algorithm used is Offset ListenInterval (OLi) algorithm.
The OLi algorithm is designed as an enhancement to the standard PS mechanisms to extend the lifetime of M2M communication networks. Use the analytical model to evaluate the energy consumption and network lifetime of proposed OLi algorithm working in conjunction with and enhancing existing PS mechanisms. Analyses shows that OLi is able to extend network lifetime by up to 40%, or 1 year, compared with standard PS mechanisms. Our results demonstrate that the proposed OLi algorithm is able to scale up to thousands of nodes for a M2M communication network.


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