Reducing Delays in Fi-Wi Networks Syd Jawad Hssain Zaidi, Hafz Bilal Khalil, Adil Bashi School of Electrical Engineering & Computer Sciences National Universi of Siences and Technolo Islamaba Pakistan Email: {10mseejzaidimseetkhalil10mscseabashir}@seecs.edu.pk Abc- Fi- Wi (Fiber- Wireless ) is the combi nation of optical networng technology and wireless networks. Fi-Wi networks are very cost effective, gives high capacity bandwidth and the best solution to full ll the demand of bandwidth hungry applications like quad play, online gaming etc. Our goal is to reduce the delays in Fi-Wi networks. In this paper we proposed m n m d n m MNMU-R) to overcome the delays in wireless (front end of Fi-Wi). Our algorithm shows the significant improvement in Delay and throughput of the network. ndx m- Delays, Fi-Wi Network I. NTRODU TION T H Fi-Wi network is the hybrid of the wireless and optical technology. Wireless networks have attractive features like broadcasting, mobility and spatial diversity where as optical technology has very high data rate which is useful for long haul communications. Front end of the Fi-Wi network is the wireless network and at the back end is optical network. The wireless network has low data rate as compare to optical network so we should have to ensure that the data packet will reach the optical par with least delay [6]. Different Protocols and routing techniques have developed to resolve this issue but they all have some deciencies. For example some routing techniques use the minimum hop count for data transfer but they do not ensure the link capacity and link quality. Some routing techniques depend on link capacity and link quality but the good quality link may not be the shorest path. In Multi-Radio Fi-Wi Network we transmit the multiple data packets on a single channel using different multiplexing techniques such as FDMA, TDMA etc. Using FDMA requires the large bandwidth and using TDMA requires more time slots for heavy trac. So still we are in search of some technique which transmits the multiple data packets at the sme TIME (inle time lot), ui the singl rquny nd uses less power to reduce the delays and increase the network throughput. II. ELATED WORK AND URRNT TATE OF THE ART Routing in WOBAN is an important issue. As we know that optical par offers very high band width and through put, to compatible with optical network wireless must be ecient. Characteristics of a WOBAN s ont end wireless mesh are dierent from that of the conventional wireless mesh. In a conventional wireless mesh, the connectivity changes due to users' mobility and dynamic or unpredictable behavior of wireless channel. On the other hand, since the WOBAN 978-1-4577-1169-5/11/$2600 ©2011 EEE mainly is a network of residential and business users, its connectivity patte in the wireless front end can be pre estimated. Many algorithms have been proposed such as MHRA, SPRA, DARA, CADA, CA, PTRA and RAAR for reducing delays. The working principle of SRA and MHA is shortest path. They select the destination path which has minimum number of nodes. MRA has unity link capacity and SPRA is inversely proporional to link capacity. Predictive throughput routing algorithm (TRA) makes decision on throughput information. It selects the path on the basis of link state advertisement. t is similar to "Predictive Wireless Routing Protocol (PWRP). PTRA is not good choice for delay sensitive applications because packet may be reached to destination through longer route (more number of nodes). Delay Aware Routing Algorithm (DARA) is another approach through which delays can be reduced [2]. DARA predicts the link state periodially. It uses MM1 queu t modl wirles routers. Capacity Aware Routing (CA) takes bottle neck capacity (BLC) metric in account. BLC is based on estimated busy time (EBT) and sele ct the route o n the basis of EBT [3]. Risk and elay Aware Routing (RADAR) is another efcient routing protocol which is extension of ARA. t has capability of handling multiple failure scenarios. Each router has a risk list (R) to the track failures [4]. If there is no failure situation then all routes will be marked live. If failure occurs on a path then risk list is updated and failure path is marked stale. So while transmitting the packet the router will choose only the live paths. DDRA delay differentiated routing algorithm is proposed to reduce they delay in the system as the Delay is an imporant meic in wireless optical network [6]. ARA is already proposed but when the load increases, delay also increases in DARA in overload conditions. DTS (elay- To-Server) is introduced as the time from the end ytm t th srer for upstram data Traf is divid in two types: DTS-sensitive and DTS-insensitive. Aer dening the TS (elay to server) thresh hold the ow below the thresh hold characterized as TS-insensitive. And ow above the thresh hold dene as DTS-sensitive. Sensitive ow also determined by knowledge of bandwidth hungry applications of end users. As a solution to decrease the delay in delay-sensitive trafc, an external buffer is introduced to the gateway router or routers that are directly connected with the gateway routers. The size of the external buffer is same as compare to inteal buffer. We cannot change or increase the size of inteal buffer of the routers as pr rule of bandwidth delay product which is typicalJy 16 Mbytes.
