ABSTRACT Mobile Cognitive Ad HocNetworks is the one of the cognitive radio networks which is the advancednetworking technologies for spectrum scarcity problem constrain in the FederalCommunication Commission (FCC). The cognitive radio networks are the cognitivenetwork which abject its network parameters with respect to networkenvironment. In cognitive radio network two users namely the primary andsecondary or cognitive users will access the available spectrum to communicateeach other when the spectrum is accessed by the primary user the secondary usermust leave the spectrum and access the spectrum when spectrum holes availablefor transmission. So routing is challenging issues in cognitive networks and itis very challenging in mobile cognitive networks due to the node mobility,primary user interface and spectrum scarcity in this paper some routingprotocols based on mobile ad hoc cognitive networks and a review on thedelay-Minimized routing protocol is presented.
KEY WORDSCognitive Radio Networks (CRN), Primary Users (PU), CognitiveUser (CU), Ad Hoc Networks. 1. INTRODUCTION Cognitive Radio Networks (CRN) is the new technology used toovercome the spectrum scarcity problem in current wireless networks by FederalCommunication Commission (FCC). In cognitive radio network is a network whichhave primary and secondary users which access the network based on DynamicSpectrum Access (DSA). The primary user is the licensed user and secondary useris unlicensed user when the licensed user is accessing the spectrum theunlicensed user are not allowed so the secondary user has to sense the spectrumperiodically to find the presence of primary user, presence of primary user isin dynamic in nature so the spectrum holes created by primary user is dynamicso the Cognitive user uses the DSA. While using the DSA routing is thechallenging in cognitive radio networks. 1.1.
Classificationof Cognitive radio networksCognitive Radio Networks (CRN) is of infrastructured andinfrastructure less, in infrastructured network it has a fixed structure likebase station primary users secondary users and so on, in infrastructurednetwork it has no fixed structure. Centralized and Decentralized networks the Centralizednetwork is the network in which has on base station in the central and haveprimary users are present. Decentralized network is the network which has nocentralized base station and has the secondary users to communicate and primaryusers Static and dynamic networks the static networks the positionof base station, primary users and secondary users are fixed but in the dynamic(Ad-Hoc) the position on primary users and secondary user will change (Mobilityis nature). 1.2. Routing in Cognitive radio networks Routingin Cognitive radio networks is based on available spectrum and knowledge ofspectrum to nodes in the network. Routing solutions for the Cognitive radionetworks is of two types one is Full Spectrum Knowledge routing and second isLocal Spectrum Knowledge routing.Local Spectrum Knowledge routing has Minimum Power Routing, MinimumDelay-based Routing, Maximum Throughput-based Routing, Geographic Routing andClass-based Routing.
This paper is organized in the following manner section 2Routing protocols in CRN,section 3 is Routing protocols of Mobile Cognitive Radio Ad-hoc Networks,section 4 is Delay-Minimized Routing protocols of Mobile Cognitive Radio Ad-hocNetworks, and section 5 is Conclusion and Future Works. 2. ROUTING PROTOCOLS IN COGNITIVERADIO NETWORKS2.1.
Spectrum-Aware Routing(SPEAR)Spectrum-AwareRouting (SPEAR) is a on demand and link based protocol support end-to-endthroughput by integration of flow-based and link-based approaches, it used RREQfor route discovery by control channels it takes decisions with collaborationof PHY and MAC layers it handle mobility issues with Timeout field in periodicchannel reservations messages. It takes the best path by maximum throughput,minimum hop count and link quality it has a communication overhead by routesetup and route tear down. 2.2. Spectrum-Aware Mesh Routing (SAMER)Spectrum-AwareMesh Routing (SAMER) is a link state routing protocol with minimum hop countand spectrum availability it gives end-to-end thought with the path with highspectrum availability, long-term stability and short-term opportunisticutilization of spectrum. The routing decisions are taken by PHY and MAC layers. 2.3.
Spectrum-Aware On-Demand Routing Protocol(SORP)Spectrum-AwareOn-Demand Routing Protocol (SORP) is an AODV protocol with control channelwhich uses the path delay and node delay (switching and back off delay) forpath selection. In route discovery phase RREQ message is broadcast with a SOPappend in the packet the control channel exchange the routing protocol messagesand it gives end-to-end thought put SORP doesn’t have link failure handlingmechanism. 2.4. Multi-hop Signal-transceiver CognitiveRadio Network Routing Protocol (MSCRP)Multi-hopSignal-transceiver Cognitive Radio Network Routing Protocol (MSCRP) is an AODVprotocol with on control channel. It is a spectrum aware routing and leaves/joins messages of the nodes so it has the communication overhead of RREQ.
Inroute discovery phase all nodes append their sate information and availablechannels set. Routing decision is taken with the collaboration of MAC, Physicaland Network Layers.2.5. Reactive source-based routing Protocol Routingin Opportunistic Cognitive Radio Networks is an on demand graph structurednetwork protocol which uses the routing metric based on the probabilisticdefinition of available capacity over channel it has no link failure handlingcapacity and it discovers the route by using OSPF, Dijkstra-link algorithm. Byusing this Dijkstra-link algorithm it gives end-to-end throughput 2.
6. Local Coordination Based Routing andSpectrum assignment in Multi-hop Cognitive Radio NetworksLocalCoordination Based Routing and Spectrum assignment in Multi-hop Cognitive RadioNetworks is a modified version of AODV which is on demand routing protocol ithas full mesh topology which uses channel scanning and beacon broadcast forneighbor discovery with control channel used for load balancing in routing. Theroute discovery is done by using RREQ and route decision is based on MAC andNetwork Layer.
It has link failure handling capability which gives lessend-to-end delay and performance. 2.7. Multipath Routing and Spectrum Access(MRSA)MultipathRouting and Spectrum Access (MRSA) is Mesh routing protocol based on roundrobin fashion data striping with minimum hop count by route discovery withcontrol channel, Broadcasting RREQ messages. The massages sent to nodesperiodically it can handle path failures by sending RERR messages and it has acommunication overhead based on multiple flows on single radio. 2.8. Cognitive Tree-based Routing (CTBR)CognitiveTree-based Routing (CTBR) is the tree based routing protocol with centralizedrouting it broadcast the root announcement (RANN) message periodically with apacket and used cumulative metric for path selection.
It selects the path basedon local and global decision schemes. It does not have route recovery mechanismto handle link failures and it has a control bytes transmission overhead. 3. ROUTING PROTOCOLS FOR MOBILECOGNITIVE RADIO Ad-Hoc NETWORKS3.1. Fault-Tolerant CognitiveAd-Hoc Routing Protocol (FTCARP)Itis a fast and efficient routing protocol for route recovery in presence of pathfailures during data deliver. It uses different route recovery mechanisms fordifferent path failures.
3.2. Cognitive Destination Sequence DistanceVector (C-DSDV) ProtocolItis a table driven routing protocol. To optimize the system performance ofmulti-hop CR ad-hoc networks by using multichannel routing table are updatedimmediately when there is change in channels the techniques is that combinesthe routing and channel allocation.
In route discover phase common controlchannel use to broadcast the route updating in the routing table in thisprotocol best path selection is based on sequence number. In C-DSDV channelswitching is used to improve the system performances. If there are more primaryusers routing over head will be increased 3.3. Cognitive Ad-Hoc On-demand DistanceVector (C-AODV) ProtocolCognitiveAd-Hoc On-demand Distance Vector (C-AODV) Protocol is based on AODV a wirelessnetwork protocol it is designed according to avoid primary users activatesregains for routing formation and packet discovery.
It gives the minimizedroute cost by forwarding packets through joint path and channel selection ateach node it takes the advantage of availability of multiple channels toimprove the overall performances. 3.4. SER-Spectrum and Energy Aware RoutingProtocolSER is an ondemand routing protocol which provide high throughput in multi-hop networks itselects energy efficient route and assign channels and timeslots for connectionrequest. The communication segment assignment algorithm is used for balancestraffic load among the CR users. In route discovery phase it broadcasts RouteRequest Messages to other nodes so it has routing overhead of RRE, RREP, RERRand ROP messages.
3.5. GYMKHANA ProtocolGYMKHANA is an ondemand routing protocol and enhanced version of AODV used the GYMKHANAalgorithm using virtual graphs and evaluate the cost by using Laplacian matrix.It has a secondary user’s self-interference over head. 3.6.
UNITED NODE ProtocolUNITEDNODE Protocol is a distributed and efficient based interference aware routingprotocol. It incorporates the spectrum availability cost and interferencemetrics into the routing algorithm to find better routes between the nodes itrepairs routes by using route preservation method. It provides adaptability tothe environment and increases throughput and reduces data delivery latency.
4. DELAY-MINIMIZED ROUTING PROTOCOLSFOR MOBILE COGNITIVE RADIO Ad-Hoc NETWORKS4.1. ROPCORN ProtocolROPCORNProtocol is the on demand routing protocol which was designed for datatransportation using link modeling and used to minimized delay for a set ofusers in network. It broadcast the packets in link with the low cast and noprimary user is affects.
ROPCORN is based on RACON protocol it uses buffers inthe intermediate nodes and forwards the packets there is no overhead due to theuse of spectrum availability and load estimation, the optimal route selectionis based on spatial or temporal locality of link disconnection. 4.2. SEARCHA Routing ProtocolIt is the ondemand routing protocol and enhanced version of AODV which is based on thegeographic routing and follow the greedy forwarding and PU avoidance for jointchannel-path optimization algorithm to find the best path. SEARCH undertakesboth the path and selection to avoid PU activity region and tries to maintainend-to-end latency it has routing overhead due to the RRE, RREP, RERR and ROPmessages.
4.3. LinkPrediction-Based Adaptive Routing Link Prediction-Based Adaptive Routing isbased on link-availability prediction. The link –availability predictionconsiders primary user activity and user mobility. This routing reduces theenergy consumption and gives least delay by enhances network performance. Itworks based on link prediction and topology control 4.4. Joint Routing andChannel Assignment JointRouting and Channel Assignment (JRCA) approach based on delay predictionand a heuristic algorithm which used the collision probability and LinkStability Prediction.
It is and on demand routing protocol which user AODVtype of routing with heuristic values and can find out the path with minimalend-to-end (e2e) delay. 4.5. AdaptiveDelay Tolerant Routing Protocol (ADTRP) The ADTRP algorithm finds a stable sequence ofinstances of the mobile graph and the communication topology of interest suchthat the number of transitions from one instance of the topology to another inthe sequence is the global minimum. The algorithm uses the average lifetime ofthe mobile graphs in the stable sequence for communication topology and it is ageneric for stable sequence of any communication topology it uses the heuristictopology for routing so it improved throughput, better packet delivery ratio, decreasedpacket drop and reduced delay. 4.
6. STOD-RP: ASpectrum-Tree Based On-Demand Routing Protocol STOD-RP is an on demand routing protocol which was designed for reducesthe control overhead and average end-t-end delay minimization and it is an extension ofthe original Ad-hoc On-demand Distance Vector (AODV) protocol which usesspectrum tree addresses, spectrum decision and route selection in an efficientway for this route matrix is used. Fast and efficient spectrum-adaptive routerecovery method is used when path is damaged. CONCLUSIONIn routing is challengingissues in cognitive networks and it is very challenging in mobile cognitivenetworks due to the node mobility primary user interface and spectrum scarcitythis paper conclude that every protocol is designed for overcome certainproblem in networks one is for multiple problems and one is for single problemlike improving performance, minimized end-to-end delay, overall throughputincreasing and so on.
There is a for more protocols or improved versions ofprotocols for increasing problems and recruitments. In further work on thispaper a delay minimized routing protocol is proposed and implemented thatimproved version protocol in NS3 will be presented.