Symmetrical Power Control for Multi-channel Multi-hop Wireless Networks

Hamid Gharavi, Bin Hu and Nan Wu

IEEE ICC 2010Speak: Huei-Rung, Tsai

A Design Framework for High-Density Wireless Ad-Hoc Networks Achieving Cooperative DiversityUSA1OutlineIntroductionGoalsSystem StructureNetwork Layer Design (CDSR protocol)MAC Layer DesignPHY Layer DesignSimulation ResultsConclusions

IntroductionIn Multiple Input Multiple Output (MIMO) systemsmeet the growing need for high-throughput reliable transmissionsIt may not be accommodated multiple antennas at the nodesVirtual MIMO mimicking the behavior of the co-located MIMO Cooperation benefitincreasing the data transmission reliabilityproviding higher throughputextending network coveragereducing the transmission delaysaving the transmit power3IntroductionHowever, there are a number of challenges for VMIMO system relay selectionnodessynchronizationthe use of a VMIMO structureThe existing cooperation schemesadditional control signals to select and maintain relaysreduces the effective throughputTDMA-based synchronizationcostly in ad hoc network (lack of base station, nodes mobility, large number of nodes)

IntroductionPrevious designs have two main issuesrelay selection process is implemented in the MAC layercontrol packets to provide handshakes between source, destination and relaythe relays are prohibited from transmitting simultaneouslyGoalsPresent a systematic design structure for high-density ad hoc networks aimed at achieving full cooperative diversity, based on which the Network, MAC and PHY layersImproved packet delivery reliabilityReduced transmission delayResistance to network topology variationSynchronous transmissions in ad hoc networksSimplicity of the proposed protocol6System StructureSourceDestinationexisting cooperative schemes, which merely use relays to enhance an existing linkcooperative routes are selected jointly in order to assist each other in every hopVMIMOsourcemulti-hopdestinationroute pathpathnodeVMIMOlinkcooperative routes 7System Structure...... ........................SourceDestination8Network Layer DesignCooperative Dynamic Source Routing (CDSR) protocol SourceDestination123456789101112131415161718192021222324302928272625DSRRREQ-RREProute pathprotocolRREQ9Network Layer DesignCooperative Dynamic Source Routing (CDSR) protocol SourceDestination123456789101112131415161718192021222324302928272625CDSRrouteRREQ(/Hop Count)sourcedestinationpath10Network Layer DesignLimit set to 11

(Node14)=7(Node15)=6(Node16)=6(Node17)=7total=26353332Distinctive pathspathtotalnoderoutemaxtotalDistinctive path

rotue11Network Layer DesignRoute Maintenance of CDSROriginal DSR

SourceDestination7891011121415161718ACK=013RERRre-establish the link by RTS/CTSHigh transmission delayDSRACKRERR12Network Layer DesignRoute Maintenance of CDSRCDSR (RERR packet initiate when both link fail )

SourceDestination7891011121415161718ACK=113NTSRTSCDSR(hop)ACKRERRACKRTSCTSDIFSACKVIFSNTS13MAC Layer DesignEvery stage of the transmissions should form a (22) VMIMO structure having two transmitters and two receiversTransmitter-1Transmitter-2Receiver-1Receiver-2Other NodesTransmitter-2Receiver-2Receiver-1TimeTransmitter-1Other NodesDIFSContentionRTSSIFSST-CTSST-CTSSIFSST-DATAST-DATANAV(RTS)NAV(CTS)SIFSST-ACKST-ACKDATAVMIMO

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MAC Layer Design

PHY Layer DesignThe challenges addressed in the PHY layer are two foldSpace-Time Block Coding (STBC) schemeseven if these nodes are scheduled to transmit simultaneously, the propagation delays by the signals from cooperative nodes are differentasynchronous cooperative MIMO system using a linear dispersion

Simulation ResultsUsing personal real-time network simulation testbed, where the invoked IEEE 802.11b standardInput data generated at a Constant Bit RateFixed 500 bytes UDP packetsdata-rate is 2 Mbpsnoise factor is 10.0. Rayleigh fadingtransmit powerintermediate nodes is set as half of the original DSRsource and destination nodes is set as the same as original DSR40 nodes are placed randomly in a 1500 m 1500 m area()18Simulation ResultsRetransmissions counter = 4

Simulation Results

ConclusionsThis paper proposed a cooperative diversity scheme for ad hoc networks. The core feature is that cooperative routes can assist the transmission of each otherhence the reliability of all wireless linksreduce the link breakage probabilityThanks For Your Attention~