ACEEE International Journal on Network Security, Vol 1, No. 2, July 2010  A Novel Parameterized QoS based Uplink and    Do...
ACEEE International Journal on Network Security, Vol 1, No. 2, July 2010polls SS by allocating bandwidth to them for the  ...
ACEEE International Journal on Network Security, Vol 1, No. 2, July 2010                              Figure 2. Scheduling...
ACEEE International Journal on Network Security, Vol 1, No. 2, July 2010queued by Earlier Deadline First mechanism and    ...
ACEEE International Journal on Network Security, Vol 1, No. 2, July 2010for through efficient utilization of bandwidth all...
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A Novel Parameterized QoS based Uplink and Downlink Scheduler for Bandwidth/Data Management over IEEE 802.16d Network

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Recent developments in Broadband Wireless
Access (BWA), caused users to use multimedia, real–time
and high bandwidth intensive applications that lead to a
new era of research and development in wireless
networks. IEEE 802.16 standard has come forward as
BWA solution to fulfill the requirements of users. Even
though IEEE 802.16 standard defines scheduling service
flows and quality of service parameters, but scheduling of
these flows to maintain QoS and fairness among flows is
left open for researchers. In this paper we developed a
scheduling architecture for IEEE 802.16 in both uplink
and downlink directions. Our scheduling architecture
includes QoS parameters like maximum sustained rate,
maximum latency, tolerated jitter, minimum reserved
bandwidth, request transmission policy, traffic priority,
burst size, SDU size and queue information for various
scheduling service flows. We use First in First out (FIFO),
Earliest Deadline First (EDF) and Self Clocked Fair
Queuing (SCFQ) to schedule different flows to achieve
QoS and efficient bandwidth utilization.

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A Novel Parameterized QoS based Uplink and Downlink Scheduler for Bandwidth/Data Management over IEEE 802.16d Network

  1. 1. ACEEE International Journal on Network Security, Vol 1, No. 2, July 2010 A Novel Parameterized QoS based Uplink and Downlink Scheduler for Bandwidth/Data Management over IEEE 802.16d Network R. Mahmood1, M. I. Tariq1 and M. S. H. Khiyal2 1 International Islamic University Islamabad Pakistan rashidmahmood@live.com, imranchaudhry12@hotmail.com 2 Fatima Jinnah Women University Rawalpindi Pakistan m.sikandarhayat@yahoo.comAbstract: Recent developments in Broadband Wireless we discuss results. Finally, we conclude with aAccess (BWA), caused users to use multimedia, real–time summary in Section VI.and high bandwidth intensive applications that lead to anew era of research and development in wireless II. BACKGROUNDnetworks. IEEE 802.16 standard has come forward asBWA solution to fulfill the requirements of users. Even IEEE 802.16d [11] standard defines an air interfacethough IEEE 802.16 standard defines scheduling service for fixed point to multipoint BWA that is competent offlows and quality of service parameters, but scheduling of providing various services. The architecture mainlythese flows to maintain QoS and fairness among flows isleft open for researchers. In this paper we developed a consists of two components, a Base Station (BS) and ascheduling architecture for IEEE 802.16 in both uplink number of Subscriber Stations (SS). Figure 1 depictsand downlink directions. Our scheduling architecture the BWA system architecture. Both BS and SS areincludes QoS parameters like maximum sustained rate, fixed, whereas users inside a building may be fixed ormaximum latency, tolerated jitter, minimum reserved mobile. Communication takes place from the BS to thebandwidth, request transmission policy, traffic priority, SSs (Downlink (DL)) and from SS to BS (Uplinkburst size, SDU size and queue information for various (UL)). DL transmission is carried through Point toscheduling service flows. We use First in First out (FIFO), Multipoint access method, and UL is conducted byEarliest Deadline First (EDF) and Self Clocked Fair Time Division Duplexing (TDD) on demand basis.Queuing (SCFQ) to schedule different flows to achieveQoS and efficient bandwidth utilization. IEEE 802.16d specifies physical layer that operates on 2-11 GHz and 10-66 GHz frequency bands. The dataIndex Terms: IEEE 802.16, Quality of Service, Broadband rate supported by these two frequency bands isWireless Access, Medium Access Control, Self Clocked dependent upon the channel bandwidth and modulationFair Queuing technique. I. INTRODUCTION Broadband wireless access (BWA) has turned outto be the best most efficient way to handle business andhome demand for fast internet access, voice/videoservices, integrated data, resource sharing andutilization, mass data transfer and multimediaapplications. It has advantages over its wiredcompetitors, such as fast deployment, ease ofimplementation, lower maintenance cost, lower upgradecost, high data rate and high scalability. Figure 1. Broadband Wireless Access System Architecture In this paper we develop an efficient schedulingarchitecture that incorporates mandatory Quality of Orthogonal Frequency Division Multiple AccessService (QoS) parameters. We have also evaluated the (OFDMA) is a potential multiple access scheme thatbehavior of fragmentation under this scheduling can very efficiently cope with these impairments. Itarchitecture. The rest of this paper is organized as considerably reduces frequency fading and inter-symbolfollows. In the next section, we provide an overview of interference [7]. The MAC layer of IEEE 802.16 isIEEE 802.16 standard (more specifically MAC layer) divided into three parts: Privacy sublayer, MACand describe some of their QoS related features. In common part sublayer and convergence sublayer. EachSection II we discussed related work. We then propose packet has to be linked with a unique connection in theour scheduling architecture in Section IV. In section V MAC layer. SSs the use bandwidth request mechanism to specify UL bandwidth requirements to the BS. BS 7© 2010 ACEEEDOI: 01.ijns.01.02.02
  2. 2. ACEEE International Journal on Network Security, Vol 1, No. 2, July 2010polls SS by allocating bandwidth to them for the OFDMA/TDD based broadband wireless accesspurpose of making bandwidth requests. Bandwidth can system, in which radio resources of both time andbe requested by sending a bandwidth request packet or frequency slots are dynamically shared by all usersby piggybacking it with a data packet. Requests can be [12]. Claudio Cicconetti et. al. in 2006, assessed theaggregated or incremental. The IEEE 802.16 standard performance of IEEE 802.16 in two of the mostdefines the following two ways for allocation of promising scenarios(residential and small and medium-bandwidth grants: Grant per Connection (GPC) and sized enterprise (SME)) envisaged by the Wimax forumGrant per Subscriber Station (GPSS). [7] and they also evaluated the effectiveness of rtPS, The standard defines four types of scheduling nrtPS, and BE through simulation in [10]. Abhishekservices, each one with distinct QoS requirements. Each Maheshwari in 2006, proposed Weighted Fair Queueconnection is linked with a single scheduling service (WFQ) based MAC scheduling architecture for IEEEand each scheduling service is linked with a set of QoS 802.16 WirelessMANs in both uplink and downlinkparameters that measure its behavior. The following directions [6]. Xiaojing Meng in 2007 proposed afour scheduling services are supported by IEEE 802.16. scheduling algorithm for OFDM/TDMA based onUnsolicited Grant Service (UGS), Real-Time Polling WiMAX network to extend proportional fairnessService (rtPS), Non Real-Time Polling Service (nrtPS) scheme to multiple service types with diverse Qualityand Best Effort Service (BE) flows. The key service of Service requirements [9].information elements (IEs) for the above mentioned In previous work, number of authors proposedscheduling services the Maximum Sustained Traffic, scheduling architecture for IEEE 802.16 and most ofMinimum Reserved Traffic Rate, Maximum Latency, them concentrated on Uplink Scheduling. Some of themTolerated Jitter, Traffic Priority and also proposed downlink scheduling, but all theseRequest/Transmission Policy. The scheduler is in scheduling architectures and mechanisms ignored thecharge of controlling the common UL bandwidth as QoS parameters defined by IEEE 802.16 to achievewell as distributing resources to flows to maintain stringent quality of service. All authors used staticquality. Fragmentation, Piggybacking, Concatenation, weights for different scheduling algorithms, while theand Contention processes are used to maintain QoS, dynamic calculation of weights was ignored. At presentresource utilization and bandwidth guarantee. there is a need for scheduling architecture, which will use all mandatory parameters defined by the IEEE III. PREVIOUS WORK 802.16 to schedule packets, and to achieve the QoS requirements of different applications. M. Hawa and D. W. Petr in 2002 suggested anuplink scheduling architecture for IEEE 802.16 and IV. SCHEDULING ARCHITECTUREDOCSIS (standard for delivering broadband servicesover Hybrid Fiber Coax) with GPC grant mode. They We proposed a scheduling architecture as shown inare more focused on DOCSIS rather than IEEE 802.16 Figure 2 for the IEEE 802.16d in the mac layer that[1]. Guosang Chu et. al. in July 2002, suggested incorporates the QoS parameter. Our proposed QoSWeighted Round Robin (WRR) as uplink scheduling scheduling architecture is composed of a BS Uplinkalgorithm with GPSS (Grant per Subscriber Station) Bandwidth Management Module, BS Downlinkgrant mode [3]. They chose five priority queues with Bandwidth Management Module, SS Uplink Scheduler,dynamic priority competitive ratio parameter BS Downlink Scheduler, Packet Ordering Module andassignment. Aura Ganz and Kitti Wongthavarawat in Fragmentation Module. We designed this scheduling2003, suggested uplink bandwidth allocation algorithms architecture to meet the QoS of each flow, and stillbased on flow type and strict priority from highest to achieve high system bandwidth utilization under GPSSlowest - UGS, rtPS, nrtPS and BE [5]. Victor Rangel1 (Grant per subscriber station).et. al. in 2004, suggested a scheduling algorithm named BS Uplink Bandwidth Management ModuleEBSA that combines Early Deadline First andPrioritization, Round Robin and Weighted Fair Queuing This module, as shown in figure 3, has theto match CBR and VBR traffic over the IEEE 802.16 responsibility for allocating bandwidth to each SS flowair interface [8]. Jianfeng Chen et. al. in 2005, for UL transmission. Its main function is to produce asuggested Quality of Service (QoS) enhancement of UL map for all SS according to their bandwidthIEEE 802.16 standard, based on cross layer requirements, to achieve excellent QoS for each flowoptimizations in PMP mode [4]. Supriya Maheshwari in under the limited information of each queue. It also2005 has described a scheduling architecture based on keeps fairness among different flows and SubscriberGPSS grant mode with WFQ for downlink scheduling Stations under overloaded conditions. It assures theand min-max fair allocation for uplink scheduling [2]. delay guarantee to UGS and rtPS flows. Bandwidth isVandana Singh et. al. in 2006, developed new allocated to each SS in the following way:scheduling algorithms for the IEEE 802.16d 8© 2010 ACEEEDOI: 01.ijns.01.02.02
  3. 3. ACEEE International Journal on Network Security, Vol 1, No. 2, July 2010 Figure 2. Scheduling Architecture for IEEE 802.16 • Amount of bandwidth allocated to each SS in Traffic Priority is used as an ordering parameter. If two regular intervals by the QoS parameters of flows are equal in Traffic priority, then priority will be connection associated with each connection. given to that flow which has less bandwidth as • Amount of bandwidth requested by each SS for UL compared to the other, and that is calculated from transmission. Maximum Sustained Rate. • Amount of bandwidth required periodically by SS’s UGS flow.BS distributed UL bandwidth among various SSs in thefollowing way. Bandwidth Allocation to UGS: BSallocates bandwidth to each UGS UL flow according toQoS parameters negotiated during connection setup.These parameters include Maximum Sustained Rateand SDU size to define the interval for allocatingbandwidth. If the number of UGS flow increases thenTolerated Jitter is used as an ordering parameter. If twoflows are equal in Tolerated Jitter, then MaximumLatency is used to break a tie. Bandwidth Allocation to Figure 3. Uplink Bandwidth SchedulingrtPS: BS fulfills the requirements of rtPS flowwhenever there is an entry in its queue. So BS providesunicast polling request to each rtPS flow to meet theQoS. BS fulfills the BW request of rtPS flows fordifferent SSs. Maximum Latency is used as an orderingparameter. If two flows are equal in Maximum Latencythen priority will be given to that flow which has lowerMaximum Sustained Rate and Minimum ReservedTraffic Rate. Bandwidth Allocation to nrtPS: BSprovides unicast request opportunities to each nrtPSflow to meet the QoS. After fulfilling the requirementsof all UGS and rtPS flows, BS provides the requestedbandwidth to different SS for nrtPS flow and Traffic Figure 4. SS Uplink SchedulerPriority parameter used as an ordering parameter. Iftwo flows are equal in Traffic priority then priority will SS Uplink Schedulerbe given to that flow which has lower Maximum After allocation of bandwidth from UL BandwidthSustained Rate and Minimum Reserved Traffic Rate as Management module, SS uplink scheduler as shown incompared to other nrtPS flows. Bandwidth Allocation figure 4, responsibility is to schedule packets from theto BE: After fulfilling the requirements of all UGS, respective queues of UGS, rtPS, nrtPS and BE. FirstrtPS, and nrtPS flows, BS fulfills the requirements of we schedule UGS packets, because there is fixedall BE flows by allocating bandwidth according to bandwidth allocation from BS side. UGS packets areMaximum Sustained Rate and Last Polling Time. The queued by FIFO mechanism. rtPS Packets are queuedparameter by Earlier Deadline First mechanism, and ordering parameter is Maximum Latency. nrtPS Packets are 9© 2010 ACEEEDOI: 01.ijns.01.02.02
  4. 4. ACEEE International Journal on Network Security, Vol 1, No. 2, July 2010queued by Earlier Deadline First mechanism and flows that have not gotten bandwidth in the currentordering parameter is Maximum Latency and Traffic frame will get it in the next.Priority. BE Packets are queued by First Come FirstServe mechanism. We use a variant of WFQ schedulingalgorithm that is Self Clocked Fair Queuing (SCFQ), toschedule rtPS, nrtPS and BE packets that avoid tocostly computation of round number in WFQ. A weightis calculated dynamically for each class of schedulingservices by the size of the queue and a constant(weight) priority connections with each flow andbandwidth distributed among flows by calculatedweight.BS Downlink Bandwidth Management Module This module, as shown in figure 5, has Figure 5. Downlink Bandwidth Managementresponsibility for allocating bandwidth to each SS forDL transmission. Its main responsibility is to produce aDL map for all SSs according to their bandwidthrequirements. To allocate DL bandwidth amongdifferent SSs is easier than UL bandwidth allocation,because BS has all information for each scheduledservice flow. It is also the responsibility of this moduleto keep fairness among different flows and SS underoverloaded conditions. The module assures the delayguarantee to UGS and rtPS flows as we increase thenumber of flows. BS distributes UL bandwidth amongvarious SSs by the following strategies. Bandwidth Figure 6. BS Downlink SchedulerAllocation to UGS: BS fulfills the requirements of UGSflow whenever a UGS packet is queued in its queue. BSallocates bandwidth to flow according to packet size. If BS Downlink Schedulerthe number of UGS flow increases then Tolerated Jitter After bandwidth allocation from downlinkis used as an ordering parameter. If two flows are equal bandwidth management module, BS Downlinkin Tolerated Jitter, then Maximum Latency is used to Scheduler’s as shown in figure 6, responsibility is tobreak a tie. Bandwidth Allocation to rtPS: BS satisfies schedule packets from the respective queues of UGS,the requirements of rtPS flow whenever number of rtPS, nrtPS and BE according to allocated bandwidth.rtPS-packets is in its queue. The parameter Maximum First we schedule UGS packets, because there is fixedLatency is used as an ordering parameter. If two flows bandwidth allocation, so that it can meet QoSare equal in Maximum Latency, then that flow has the efficiently. After scheduling UGS packets, thepriority, which has less allocated bandwidth, and it remaining bandwidth is allocated among rtPS, nrtPScalculated from Maximum Sustained Rate and Minimum and BE flows. These packets are scheduled by SCFQReserved Traffic Rate. While ordering flows, there is scheduling algorithm, which finds the finish number ofone important aspect where a flow, which is much each packet before its introduction into the respectivecloser to maximum latency, is crossing a deadline. Here queue, and this algorithm also updates the roundit is better to drop the packets instead of allocating very number after each arrival and departure of packets.costly bandwidth. Bandwidth Allocation to nrtPS: BS Weight is calculated by the mechanism described in SSfulfills the requirements of all nrtPS flows according to Uplink Scheduler.size of packets that are queued in its queue. The Fragmentation Moduleparameter Traffic Priority is used as an orderingparameter. If two flows are equal in Traffic priority, This module is mainly responsible for allowingthen that flow has the priority, which has, less allocated efficient use of granted bandwidth relative to the QoSbandwidth as compared to the other, and that is requirements of a connection. We do not fragment thecalculated from Maximum Sustained Rate and Minimum UGS connection, because there is fixed allocation ofReserved Traffic Rate. Bandwidth Allocation to BE: At bandwidth. This process is performed before BSlast it fulfills the requirements of all BE flows. Traffic scheduler and SS scheduler schedule the packets. ItsPriority is used as an ordering parameter to allocate main task is to fragmenting the packets whose size isbandwidth among BE service flows. In the second greater than that allocated for a packet. In these casesstage, BS allocates DL bandwidth to all SSs. Service header overhead increases, but this can be compensated 10© 2010 ACEEEDOI: 01.ijns.01.02.02
  5. 5. ACEEE International Journal on Network Security, Vol 1, No. 2, July 2010for through efficient utilization of bandwidth allocated easily schedule packets. We concluded that to achieveto each SS. quality of service, efficient utilization of bandwidth and fairness, the best method is to design such an V. RESULT architecture that incorporates all QoS parameters, so a flow can meets its delay and bandwidth guarantee. ThisWe performed a number of simulation tests in Network approach can save a BS from excessive computationSimulator 2 (NS-2) to show the effectiveness and and databases management overhead for each flow.performance of our proposed scheme. Figures 7 and 8 Finally, we concluded that such architecture is best forshow the Mean Mac delay of scheduling service flows the varied quality of service requirements of differentto SS (UL and DL) when the number of SSs increases flows in UL and DL directions.from 2 to 24. It is found that mean delay of allscheduling flows in UL direction increases gradually REFERENCESafter overloaded condition, except for UGS. With UGSflows, BS provides a unicast request opportunity to all [1] M. Hawa and D. W. Petr, “Quality of service schedulingrtPS connections at a predefined time. in cable and broadband wireless access systems,” 10th IEEE Mean delay of each type of traffic in DL direction International Workshop on Quality of Service, pp. 247–255, May 2002.remains constant because queues are empty. When the [2] Supriya Maheshwari, “An Efficient QoS Schedulingsystem is overloaded, the average delay of BE and Architecture for IEEE 802.16 Wireless MANs,” MasternrtPS flows increases more sharply than UGS and rtPS Thesis, IIT Bombay, 2005.flows. Flow Priority and delay tolerant traffic are the [3] Guosong Chu, Deng Wang, and Shunliang Mei, “A QoSmain parameters for providing bandwidth for UGS and architecture for the MAC Protocol of IEEE 802.16 BWArtPS flows. Scheduling algorithm tries to maintain the System,” IEEE International Conference on Communicationsreserved rate allocated to UGS and rtPS connections as Circuits and System and West Sino Expositions, vol. 1, pp.the number of subscriber stations increases, and it also 435–439, China, 2002.tries to shape the rate of quarantine to other flows. [4] Jianfeng Chen, Wenhua Jiao, Qian Guo, “Providing integrated QoS control for IEEE 802.16 broadband wireless access systems,” Vehicular Technology Conference, IEEE 62nd, vol 2, 2005. [5] Aura Ganz and Kitti Wongthavarawat, “IEEE 802.16 based last mile broadband wireless military networks with quality of service support,” IEEE Milcom 2003, vol. 2, pp. 779–784. [6] Abhishek Maheshwari, “Implementation and Evaluation of a MAC Scheduling Architecture for IEEE 802.16 Wireless MANs,” Master Thesis, IIT Kanpur, 2006 [7] Claudio Cicconetti, Luciano Lenzini, Enzo Mingozzi and Eklund, “Quality of Service Support in IEEE 802.16 Figure 7. Mean Mac delay of Scheduling Services (UL) Networks,” IEEE Network, March/April 2006 [8] Victor Rangel1, Javier Ortiz and Javier Gomez. “Performance Analysis of QoS Scheduling in Broadband IEEE 802.16 Based Networks,” OPNETWORK 2006 technology conference, Washington D.C, August 2006, [9] Xiaojing Meng “An Efficient scheduling for Diverse QOS Requirements in WiMAX,“ Master Thesis, Waterloo, Ontario, Canada, 2007. [10] Claudio Cicconetti, Alessandro Erta, Luciano Lenzini, and Enzo Mingozzi, “Performance Evaluation of the IEEE 802.16 MAC for QoS Support” IEEE Transaction on Mobile Computing, 1st ed, vol. 6, January 2007 [11] IEEE 802.16-2004, IEEE Standard for Local and Figure 8. Mean Mac Delay of Scheduling Services (DL) Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems, IEEE, Oct 1, 2004. VI. CONCLUSION [12] Vandana Singh and Vinod Sharma, “Efficient and Fair Scheduling of Uplink and Downlink in IEEE 802.16 OFDMA In this paper we proposed a scheduling architecture, Networks,” Wireless Communications and NetworkingIEEE 802.16 standard, for UL and DL direction that Conference IEEE, vol. 2, pp 984-990, 2006.incorporates QoS parameters associated with each [13] Abhey K. Parekh and Robert G. Gallager, “A generalizedscheduling service. Packets are scheduled according to processor sharing approach to flow control in integratedthese QoS parameters. We concluded that DL services networks the single node case,” IEEE/ACM Trans.scheduling is easy to arrange, because BS has all the Networking, vol. 1, pp. 334–357, June 1993.information about flows and updated queue, so we can 11© 2010 ACEEEDOI: 01.ijns.01.02.02

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