1 | Page DELAY AWARE POWER SAVING SCHEME (DAPSS) BASE ON TRAFFIC LOAD IN IEEE 802.16e NETWORKS. Daniel Dauda Wisdom Department of Mathematics Usmanu Danfodiyo University Sokoto, Nigeria danieldaudawisdom1@gmail.com Ahmed Audu Department of Mathematics UUDS, Nigeria ahmed.audu@udusok.edu.ng Ahmed Yusuf Tambuwal Department of ICT Usmanu Danfodiyo University Sokoto (UDUS), Nigeria ahmed_tambuwal@yahoo.com Michael Bamidele Soroyewun Department of Computer Science Ahmadu Bello University, Zaria delemike@gmail.com Aminu Mohammed Department of Mathematics Computer Unit, UDUS Nigeria. maminuus@yahoo.com Samson Isaac Department of Computer Science Kaduna State University Kaduna, Nigeria samson.isaac@kasu.edu.ng ABSTRACT IEEE 802.16 Standard also known as worldwide interoperability for Microwave Access (WiMAX) is designed to support wider coverage, higher bandwidth, less cost of deployment with different traffic classes’ support for power savings. The IEEE added mobility characteristics which made battery- life of Mobile Station (MS) a critical challenge, since MS are battery powered with an impose rechargeable life. An Efficient Battery Lifetime Aware Power Saving Scheme was proposed. The Scheme minimizes frequent transition of MS in order-to reduce power consumption but increases average response delay due to a longer sleep interval used. Thus, a Delay Aware Power Saving Scheme (DAPSS) Based on Traffic Load is proposed to reduce the excessive response delay. The Scheme introduces a modified minimum and maximum sleep interval in order to reduce the longer sleep time of a MS, and dynamically tunes the sleep parameters more appropriately according to the traffic load. It employed a delay aware algorithm to save power. The Scheme was evaluated using discrete event simulator, the results showed that the proposed DAPSS achieves superior performance compared to the existing Scheme in terms of the average power consumption and response delay. KEYWORDS: Battery-Life, Delay-Aware, IEEE, Power-Saving-Scheme. 1. Introduction The IEEE 802.16 also known as Worldwide Interoperability for Microwave Access (WiMAX) is designed to support wider coverage, higher bandwidth, less cost of deployment, quality of service (QoS), with vast traffic classes support to users as well as smaller scale business. As one of the emerging broadband wireless access systems for mobile stations (MS). Formally, the IEEE 802.16 is designed for a fixed MS [1], while subsequent version of the IEEE 802.16e is an extension of the former standard with mobile features so that MS could be move-able (Mobile) [2]. And because of the significance of the mobility characteristics added in the subsequent 802.16e standard, efficiency subsequently became a critical challenge for battery-powered devices since MS are battery powered with a rechargeable supper impose lifetime. Power Saving Classes (PSCs) of type I, II, and III are designed to address the challenges mentioned above. Type I is designed for best effort (BE) and non-real- time variable rate (NRT-VR) traffics, it consists of listening intervals as well as sleep intervals which are interleaved respectively (Figure 1). The length of the listening intervals in this power saving class is fixed. A MS with PSC I subsequently checks if there are some buffered packets for it in the listening intervals (Figure 4 and 5). If there are buffered packets, the MS will revert to normal operation mode to receive the packet (s). Else, the sleep window is activated in order to further save power. This procedure is repeated and the length of the sleep intervals is doubled until it reaches the maximum length of the sleep window called Tmax and maintains Power Savings [18]. PSC of Type II is for unsolicited grant service (UGS) and real time variable rate (RT-VR) traffics, similarly type II consists of listening intervals and sleep intervals. Unlike type I, the length of listening and sleep intervals are both fixed for PSC of type II and the sum of the sleep windows is called, the sleep cycle. PSC II is also capable of transmitting data packets without returning to normal operation. Thus, the length of listening intervals is long enough to receive all packets arriving during a single sleep cycle in PSC II [19] (Figure 1). PSC of type III is use for managing operations and multicast connections. These three PSC differ from each other by their parameter sets, methods of activation/deactivation, as well as the policies of MS availability for data transmission [2]. Unlike PSC of type I and II, PSC III comprises of a single sleep intervals and is mainly use for multicast connection as well as management of operations as seen in Figure 1 below. By activating the PSC, a single sleep interval with defined length in