Presentation on theme: "Computer Engineering/VLSI Seminar"— Presentation transcript:
1 Computer Engineering/VLSI Seminar Enhancing Throughput of Multihop Wireless Networks using Multiple Beam Smart AntennasVivek Jain(Bachelor of Technology (E&C), Indian Institute of Technology at Roorkee, India, 2002)PhD Candidate OBR Center for Distributed and Mobile ComputingECECS Department, University of CincinnatiThesis Title: On-Demand Medium Access with Heterogeneous Antenna Technologies in Multihop Wireless NetworksThesis Advisor: Dr. Dharma P. Agrawal
2 Outline Introduction Analytical Framework Multihop Wireless NetworksAntenna TechnologiesMedium Access Control ProtocolsAnalytical FrameworkIEEE DCF based Protocols for MBAAESIF MechanismAMD for Beamforming AntennasHMAC for MBAASummary of the Research WorkFuture Work
3 Introduction – Wireless Network Infrastructure-based – Devices communicate with central Access Point (AP). Also, referred to as Wireless Local Area Network (LAN).Peer-to-peer – Any two devices can communicate, when in range. Also, referred to as Personal Area Network (PAN) or an Ad hoc Network.
4 Introduction – Multihop Wireless Network (MWN) Intermediate nodes act as routers or relay nodesMultihop forwarding to ensure network connectivityExtends coverage of single hop wireless networksMultihop wireless networks offerScalabilityReliabilityAdaptabilityEasy deployment in rough terrains
5 Introduction – Mobile Ad hoc Network (MANET) Set of mobile station (MSs)Lack of fixed infrastructure relay nodesDynamically changing topologyApplicationsMilitary - Combat Systems, reconnaissance, surveillanceDisaster managementMedical emergencyVirtual navigationDistance education
6 Introduction – Wireless Mesh Network (WMN) A combination of infrastructure-based and peer-to-peer networksSet of mobile and immobile stationsDynamically changing topologyApplicationsIntelligent transport systemsPublic safetyPublic internet accessResidential broadband accessDistance education
7 Introduction – Wireless Sensor Network (WSN) Usually a set of small immobile nodes referred as motesGenerally static topologyCheap alternative to monitor inaccessible or inhospitable terrainsApplicationsMedical Applications – wireless bio-sensorsNuclear and chemical plantsEnvironmental monitoringOcean monitoringBattlefields
8 Introduction – Challenges in MWN Medium access protocolsRouting protocolsTransport ProtocolsCross layer optimizationNetwork capacity utilizationSecurityNetwork lifetime in WSNCo-existence of several types of MWNNetwork layer and Medium access layerSmart Antennas and MIMOMANET,WMN, andWSN
9 Introduction – Antennas Omnidirectional Antenna – Low Throughput in Wireless Ad hoc networks due to poor spatial reuse.ABCDEFGHDirectional CommunicationDirectional Antenna – Better Spatial reuse. But a node still unable to fully utilize “spatial bandwidth”.ABCDFGHXNodes in Silent ZoneEOmnidirectional Communication
10 Introduction – Multiple Beam Smart Antennas Also referred as Multiple Beam Antenna Array (MBAA) – Exploits spatial bandwidth fully.A node can initiate more than one simultaneous transmissions (or receptions).AEDATADATADBFCG
12 Introduction – Antenna System Phased Array AntennaIncident Wave213Greater the number of elements in the array, the larger its directivity12345674d7568 Element Linear Equally SpacedAntenna Array8 Element Equally Spaced Circular Antenna Array
13 Introduction – Beamforming … …… …Direction of Arrival EstimationBeam FormationAs all antenna elements are used for beamforming, a node can either transmit or receive simultaneously, but not both.
14 Introduction – Medium Access On-Demand or Contention-basedScheduling or Contention-freeChannel AllocationDynamicPre-definedTopological Change AdaptationGoodNew Schedules RequiredTime SynchronizationNoYesEnergy UtilizationUncontrolledControlledConcurrent Receptions or TransmissionsLocal Synchronization RequiredInherentOn-demand vs. scheduling medium access control protocols
15 MBAA Model Assumptions A wide azimuth switched-beam smart antennaAntenna array has M elements that forms non-overlapping sectors spanning an angle of 360/M degreesBeam shape is assumed as conicalBenefits of nulling or the impact of side-lobe interference are not consideredCarrier sense is performed directionallyA collision occurs only if a node receives interfering energy in the same beam in which it is actively receiving a packetRange of omnidirectional and directional beam is the same3241Directional Coverage AreaMOmni-directional Coverage AreaM-1The Antenna Model
16 Analytical Framework Can we develop an analytical framework to: Calculate throughput of on-demand medium access control protocols?Calculate concurrent packet reception capability of medium access control protocols?Calculate upper bounds of throughput for the ideal MAC in a multihop wireless network that can provide as a benchmark to compare with the proposed protocols?
17 Slotted AlohaSlotted Aloha throughput with N=50, a=0.01 and p=0.03
18 CSMACSMA throughput with N=50, a=0.01, p=0.03 and f =0.03
19 Concurrent Packet Reception Bounds Percentage of CPR for asynchronous on-demand receiver-initiated protocols
20 Concurrent Packet Reception Bounds Percentage of CPR for asynchronous on-demand transmitter-initiated protocols
21 Throughput Bounds – Ideal MAC DestinationSourcew1w2whwhere, h is hop-lengthComm_Duration is communication time taken by a packet on each hopAlso,
22 IEEE DCF for MBAADoes the existing IEEE DCF based MAC protocols for single beamforming antennas yield optimal results for MBAA also?If not, then what are the features that are needed in a protocol to leverage the benefits of MBAA?
23 IEEE DCFDe-facto medium access control for wireless LAN and ad hoc networksOriginally designed for omnidirectional communication, its virtual carrier sensing (VCS) mechanism is enhanced for directional communication to include directional of arrival also.
24 IEEE 802.11 DCF for Multiple Beam Antennas All nodes employ IEEE DCF with directional virtual carrier mechanism (DVCS).Transmission Control Packets (RTS/CTS)DirectionalOmnidirectionalMDMAC-BBMDMAC-NBMMAC-BBMMAC-NBBeam-basedNode-basedRandom Backoff after DIFS wait
25 Performance Evaluation Packet generation at each source node is modeled as Poisson process with specified mean arrival rateEach packet has a fixed size of 2000 bytes and is transmitted at a rate of 2MbpsEach node has maximum buffer of 30 packetsEach packet has a lifetime of 30 packet durationsEach simulation is run for 100 seconds.123487Directional Coverage AreaOmnidirectional Coverage Area56Gains from spatial reuse only are consideredThe Antenna Model
26 Performance Evaluation BCDEGFPerformance EvaluationNone of the protocols are able to extract throughput of more than 33% of the maximum possible valueThis implies only one route is active on an average and hence concurrent packet reception is not occurring at node D.
27 ESIFCan we have an on-demand medium access protocol that can yield nearly optimal results in multihop wireless networks with MBAA?If yes, thenIs the protocol synchronous or asynchronous or a hybrid of both?Does the protocol support differentiated service classes?
28 MAC – Issues Concurrent Packet Reception with IEEE 802.11 DCF DIFSERTSRTSRTSDATAACKCTSDIFSDBFRTSRTSRTSRTSCTSRTSCGConclusion: Eradicate the backoff after DIFS duration
29 MAC Issues – Backoff Removal Multiple transmitters, located in the same beam of common receiver, always get the same receiver schedule and thus initiate communication at the same time - collisionA node with very high data generation rate will overwhelm its receiver, without giving latter a chance to forward this traffic - fairness issueAll classes of service get same priority – QoS issueUse p-persistent CSMADIFSARTSXRTSBCDIFSABCDIFSDIFSCTSACKRTSDATAHold the transmitting node
30 ESIF – ENAV Every node maintains an ENAV: The beam a neighbor falls withinNeighbor’s schedule - the duration until this neighbor is engaged in communication elsewhereWhether a neighbor’s schedule requires maintaining silence in the entire beamNumber of data packets outbound for the neighborThe p-persistent probability to use when talking to this neighbor
31 ESIF – Cross Layer Data Management Using network layer information along with ENAV a node determines:Whether a beam contains an active routeThe number of potential transmitters in each beamUntil what time the node needs to maintain silence in a particular beamEach node has a store-and-forward buffer for relaying data packetsAvailable buffer is used dynamically to form different queues for each beam - prevents head-of-the-line blocking
32 ESIF – DesignESIF piggybacks feedback onto control messages; RTS with Intelligent Feedback (RIF), and CTS with Intelligent Feedback (CIF), Schedule Update with Intelligent Feedback (SCH)SCH identifier allows a neighbor to adjudge whether to defer transmission for only this node or for the entire beambuffer-threshold to control priorities between receiver and transmitter modesReception gets priority as long as the buffer size remains under the thresholdIf a node cannot actually initiate transmitter mode, the receiver still gets the priorityPriority switch solves problems of an overwhelmed receiver.This also provides a mechanism to control the contribution of a node to end-to-end delays
34 Performance Evaluation BRemoval of contention window based backoff in ESIF does not affect long-term fairnessBoth the transmitters get equal opportunity to transmit
35 Performance Evaluation BACDPerformance EvaluationESIF enhances throughput by the priority switch between transmission and reception modesESIF is able to achieve concurrent data communications between node pairs A-B and C-D
36 Performance Evaluation BCDEGFPerformance EvaluationESIF is able to achieve CPR at common intermediate node DDynamic priority switch ensures data packets just received are transmitted (concurrently) in the next cycle, thus, maximizing throughput and minimizing delay
37 Concurrent Packet Reception Bounds Percentage of CPR for IEEE over four and eight beam antennasPercentage of CPR for ESIF over four and eight beam antennas
38 QoS over ESIF Mechanism Multilevel Queue Organization in each beam of the sender in SS-MQOMultilevel Sender Queue (MSQ) at the receiver in RICS
39 Performance Evaluation BADCPerformance EvaluationEach node generate class 0, class 1 and class 2 packets with probabilities 0.2, 0.3 and 0.5, respectively, while they are selected with respective probabilities of 0.5, 0.3 and 0.2Prioritized flow selection is enforced more strictly in RICS as QoS parameters are applied at two ends – sender and receiver
40 Directional Coverage Area Omnidirectional Coverage Area BeamformingAdvantagesLonger RangeBetter connectivity and lower end-to-end delaySpatial ReuseIncreased capacity and throughputLimitationsDeafness and hidden terminal problemsNode is unaware of ongoing communication in the neighborhood regions where it not currently beam-formed123487Directional Coverage AreaOmnidirectional Coverage Area56
41 Deafness ProblemXRTSABDATARTSYNodes X and Y do not know the busy state of node A and keep transmitting RTSs to A
42 Deafness – Consequences At transmitterIncreases retransmission attempts after doubling contention window for every unsuccessful attemptAt receiverCan increase collisions due to interference with active RTS or data receptionsOverall NetworkReduces throughput and increases end-to-end latency
43 Deafness – Proposed Solutions (Single Beam Antennas) Omni-directional transmission of control messagesAsymmetry in gain of directional and omni-directional nodes leads to deafnessCircular sweeping of control messagesIncreases end-to-end delay due to sweeping
44 Deafness – Proposed Solutions (Multiple Beam Antennas) Proactive approachA node transmits control messages in all free beamsReactive approachA node transmits control messages in all beams that are free and have potential transmitters
45 Proposed Algorithm Hybrid Approach Uses DVCS mechanism to dynamically maintain two parameters for every beamisRTSReceived: Set to true when a node receives a RTS intended for itselfisCTSReceived: Set to true when a node receives a CTS not intended for itselfTransmit control messages in all unblocked beams whose isRTSReceived is set to trueTransmit control messages in all unblocked beams if isCTSReceived is true for the beam engaged in actual data communicationSCHCTS
46 Performance Evaluation BDThroughput obtained in MMAC-NB is low due to collisions occurring at node D from transmissions by nodes A and BThe topology has no effect on ESIF as control messages are sent only in routes with potential transmitters
47 HMACCan we have a medium access control protocol that can support both omnidirectional and beamforming antennas including MBAA?If yes, thenIs the new protocol backward compatible with IEEE DCF?Does this protocol reach ideal throughput upper bounds?Can we have cost-effective mesh network architecture?
48 HMAC - FeaturesCan we have a medium access control protocol that can support both omnidirectional and beamforming antennas including MBAA?If yes, thenIs the new protocol backward compatible with IEEE DCF?Does this protocol reach ideal throughput upper bounds?Can we have cost-effective mesh network architecture?
49 HMAC – Enhancements over ESIF Employs Algorithm for Mitigating Deafness while transmitting control packetsExploits a Run-time Sender Estimation AlgorithmDoes not rely on neighbor feedbackMaintains same packet formats for control messages as in IEEE DCF and is thus compatible with itSimpler implementation as compared to ESIF
50 HMAC/IEEE Frame control field for control messages (RTS/CTS) HMAC – Packet FormatsHMAC/IEEE RTS packet formatHMAC SCH packet format for RTSHMAC/IEEE CTS and ACK packet formatHMAC SCH packet format for CTSHMAC/IEEE Frame control field for control messages (RTS/CTS)
51 Performance Evaluation BCDEGFPerformance EvaluationWith basic access mechanism similar to ESIF, HMAC is able to deliver optimal performance
52 Performance Evaluation DBAECPerformance EvaluationRun-time sender estimation algorithm employed in HMAC delivers comparable performance to ideal p-persistent mechanism exploited in ESIF
53 Mesh Network Architecture Wired internet backboneAccess Point1Wireless Routers312211475613814209101918171516Mobile Users
54 Summary – Analytical Framework Evaluated the performance of slotted Aloha and basic CSMASlotted Aloha gives better throughput than basic CSMA at lower loadsAt heavier loads, CSMA gives better performanceAsynchronous on-demand protocols like CSMA gives stable results for MBAA at higher loadsHowever, as number of beams increases, throughput per beam in CSMA falls due to synchronization lossesDeveloped analytical framework for calculating concurrent packet reception capability of asynchronous protocolsThroughput in CSMA can be enhanced by using localized synchronization and properly adjusting transmission probability p of nodes such that Np>2, where N is the number of contending nodes.Calculated throughput upper bounds for an ideal MAC
55 Summary – IEEE 802.11 DCF Based MAC Protocols for MBAA Concurrent packet reception in multiple beam antennas is highly improbable with IEEE DCF based protocolsAsynchronous protocols thus cannot leverage the benefits of MBAAA new MAC protocol based on the formulated guidelines is required.
56 Summary – ESIFESIF is the first attempt to achieve concurrent packet reception with on-demand protocols for MBAAESIF removes the contention window based random backoff in IEEE DCF based protocols and uses embedded feedback to synchronize neighboring nodesAllows nodes to receive or transmit multiple packets simultaneously in different beamsCross layer information is used to guarantee long-term fairnessESIF is a hybrid of synchronous and asynchronous on-demand medium access controlTwo protocols, SS-MQO and RICS to support QoS over ESIF mechanism, are proposed recently.
57 Summary – HMACHMAC is the first attempt to allow coexistence of mesh and ad hoc networks with heterogeneous antenna technologiesHMAC is backward compatible with IEEE DCFExploits Algorithms for Mitigating Deafness and Run-time Sender Estimation to achieve optimal performance
58 Future Work – MIMO Antennas Single-user MIMOSpectral efficiency is increased by supporting multiple data streams over spatial channels.Spatial diversity is exploited to enhance the detection performance.Multi-user MIMOMIMO channel is evenly divided and allocated to multiple users.Each user channel has access to the space domain over entire transmission channel and frequency bandwidth.Source: Benjamin K. Ng and Elvino S. Sousa, “SSSMA for Multi-User MIMO Systems”, IEEE Microwave Magazine, vol. 5 , pp , June 2004
59 Future Work – MIMO Antennas Source: Group MIMO Comes of Age.pdf
60 Outline of Proposed Work Multihop Wireless Network (MWN)Unified MACWireless Mesh Network (WMN)Wireless Sensor Network (WSN)Mobile Ad hoc Network (MANET)MSCMDMAC-BB;MDMAC-NB;MMAC-BB;MMAC-NBHybrid MACMIMO MACReliableMACOn-Demand Medium Access Control (MAC)SS-MQO;RICSESIFEnergyEfficientReliableMACAMDSingle Beam AntennaMultiple Beam Antenna Array (MBAA)Omnidirectional AntennaSmart AntennaMultiple Input Multiple Output (MIMO) AntennaWork completedWork in progressCo-authoredAntenna Technologies
61 PublicationsDhananjay Lal, Vivek Jain, Qing-An Zeng, Dharma P. Agrawal, “Performance Evaluation of Medium Access Control for Multiple Beam Antenna Nodes in a Wireless LAN,” in IEEE Transactions on Parallel and Distributed Systems, Vol.15, No. 12, pp , 2004.Vivek Jain, Nagesh S. Nandiraju, and Dharma P. Agrawal, “Mode Selection Criteria in Mobile Ad hoc Networks using Heterogeneous Antenna Technologies,” in Proceedings of OPNETWORK 2005, Aug 2005.Vivek Jain, Anurag Gupta, Dhananjay Lal, and Dharma P. Agrawal, “IEEE DCF Based MAC Protocols for Multiple Beam Antennas and Their Limitations,” in Proceedings of IEEE MASS, NovVivek Jain, Anurag Gupta, Dhananjay Lal, and Dharma P. Agrawal, “A Cross Layer MAC with Explicit Synchronization through Intelligent Feedback for Multiple Beam Antennas,” in Proceedings of IEEE GlobeCom, NovVivek Jain and Dharma P. Agrawal, “Mitigating Deafness in Beamforming Antennas,” in Proceedings of IEEE Sarnoff Symposium, March 2006.Ratnabali Biswas, Vivek Jain, Chittabrata Ghosh, and Dharma P. Agrawal, “On-Demand Reliable Medium Access in Sensor Networks,” in IEEE WoWMoM 2006 (accepted).Anurag Gupta, Vivek Jain, and Dharma P. Agrawal, “Differentiated Service Classes Over Multiple Beam Antennas,” manuscript submitted.Vivek Jain and Dharma P. Agrawal, “Concurrent Receptions with On-Demand Medium Access Protocols for Multiple Beam Antennas,” manuscript submitted.Vivek Jain, Anurag Gupta, and Dharma P. Agrawal, “On Medium Access in Multihop Wireless Networks with Heterogeneous Antenna Technologies,” manuscript submitted.
62 For more information http://www.ececs.uc.edu/~jainvk Questions ???For more informationThank You!!!
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