Routing Protocol of Cognitive Ad Hoc Network
International Journal of Future Generation Communication and Networking
This paper proposes a priori cross layer routing protocol CLC-DSDV routing protocol in cognitive Ad Hoc network, the protocol will combine channel management mechanism and DSDV routing protocol in Ad Hoc network, and aiming at the existing problem of multi channel DSDV-MC routing protocol such as primary user interference, routing load imbalance, routing reconfiguration have been improved, in order to achieve the effective use of wireless spectrum of cognitive Ad Hoc networks. Concrete
... . Concrete improvements on the routing protocol are described: joining the node load considerations in the routing process; through the information of the global routing table of each node for distribution in channel allocation; channel allocation information embedded in routing newspaper information and broadcasting timely; starting routing update packets to ensure compliance with the neighbor node information synchronization at the channel switching time. The simulation of the routing protocol based on NS2, the simulation results show that the CLC-DSDV routing protocol can effectively improve the utilization of licensed spectrum rate, throughput, delay, packet loss rate, routing load and other aspects can be more outstanding than the original multi channel routing protocol DSDV-MC. 260 Copyright ⓒ 2015 SERSC existing research mainly adopt three kinds of methods: one is based on the existing wireless network with link adaptation technology, modulation and coding of advanced technology and multi antenna technology; the second category is the coexistence of a variety of wireless transmission technology of communication system, such as ultra wideband system work at the frequency of 3.10GHz and traditional narrowband systems coexist techniques, but these techniques to improve the spectrum utilization efficiency while increasing the interference limits the capacity of the communication system and flexibility. The third catego ry is the cognitive radio technology. In the three methods of cognitive radio technology is considered to be the most suitable for outdoor communication technology. The proposed cognitive radio technology to solve the problem of the shortage of spectrum resources this thorny problem. The technology can be understood as a dynamic spectrum allocation technology in terms of spectral distribution. The concept of cognitive radio was first proposed by Dr. Joseph Mitola in 1999, which is mainly to solve the problem of spectrum resource scarcity, the basic idea is to improve the utilization of available spectrum. The basic starting point of cognitive radio is: in order to improve the spectrum utilization, with cognitive function unlicensed users (secondary users) can be in the authorized user has licensed spectrum (primary users) without or communication service only a few cases in accordance with certain "opportunistic (Opportunistic Way)" the way to work in the licensed frequency band within this spectrum resources appear in the space domain, time domain and in frequency domain can be used to be called "spectrum holes"). The core idea of cognitive radio is to make the wireless communication device has found "spectrum holes" and to achieve "spectrum sharing" premise does not affect the main user communication, the final completion of the wireless communication process. Once the cognitive network system discovery that it can find appropriate "spectrum holes" for communication, cognitive network will carry on the wirele ss communication packets on the upper application. To find the appropriate "spectrum holes", the mobile terminal needs perceived in advance communication environment (such as the spectrum hole, geographical location, available wireless system or network, suitable type of service), and in view of the user characteristics and n eeds analysis, and then reconfigured to the case of adaptive change of system parameters on its. For example, when the cognitive mobile terminal sense there is the presence of the WiFi network and GSM network in the surrounding environment, and digital TV band surrounding the existence of spectrum holes, the cognitive wireless terminal may decide to download files via WiFi network, a phone call is made through the GSM network, and communicate through the spectrum holes and other cognitive users. Cognitive terminal can negotiate with other cognitive users to determine the effective communication frequency in order to achieve communication. The negotiation process may be through wireless networks are the underlying infrastructure may also be done through an Ad Hoc network. Cognitive radio network with the traditional wireless network has a significant difference, the latter is assigned using immobilized spectrum, thus causing a spectrum utilization rate reduce. The cognitive radio network is dynamic spectrum allocation for wireless applications in the surrounding environment and dynamic adjustment of the communication parameters (such as the communication carrier frequency channel transmit power). When the main user (authorized users) exist, user cognitive network must unconditionally release spectrum. That is to say, in cognitive radio network, we must guarantee the communication not cognitive users generate communication interference to primary users. Cognitive radio technology as the free use of spectrum resources technology, in the Ad Hoc network application is very appropriate, especially suitable for the Ad Hoc cognitive radio emergency network. However, when the application of cognitive radio technology in low power multi hop Ad Hoc networks, because of its multi hop communication, dynamic network topology changes, the spectrum state with time and physical location changes and other characteristics, to realize the system needs a new MAC protocol and the new routing protocol. Generally speaking, communication between cognitive users need to use a shared transmission control channel to complete the routing and signaling control information in one or more of the. In cognitive Ad Hoc network technology research in an important characteristic is, meet all kinds of the solution of the problem must be considered together, the design process in the multi-layer protocol in which the cognitive radio technology, routing technology is the key technology of dynamic spectrum access in cognitive scene in Ad Hoc network. Similar to general cognitive network, Ad Hoc network is composed of cognitive secondary users (i.e., non authorized users, the cognitive user) composition, spectrum resources in the secondary users, the primary user (i.e., authorized users) can always deprivation, the occupation of the corresponding spectrum, which leads to the available channel resources of the whole of the cognitive network with time, spatial variation. Cognitive radio system can be divided into three functional modules: cognitive modules (perceived environmental parameters), self organizing module (analysis of perceived information), reconfiguration module (adaptive adjustment of the wireless resources). Related Work The characteristics of Ad Hoc networks have not infrastructure, the mobile node in Ad Hoc network can be directly with the neighbor node (node receives its emission range) the connection, the overall mobile nodes form a network. Establish the communication between different nodes can be connected through different communication technologies. Ad Hoc network is a special kind of wireless mobile network, due to the wireless channel, the limited power, distributed control technology, it is more vulnerable to eavesdropping, active intrusion, denial of service, deprived of "sleep" and other network attacks. In addition, Ad Hoc network is composed of nodes act as routers themselves, not the existence of naming server and directory server and other network facilities, also does not exist the concept of network boundary. This makes the security problem of Ad Hoc network is very complex, the traditional network of many security policies and mechanisms will no longer apply. Therefore, channel encryption, anti disturbance, user authentication, key management, access control and other safety measures need special consideration. Cognitive radio technology as the free use of spectrum resources technology, in the Ad Hoc network application is very appropriate, especially suitable for the Ad Hoc cognitive radio emergency network. However, when the application of cognitive radio technology in low power multi hop Ad Hoc network, to realize the system needs a new MAC protocol and the new routing protocol. Generally speaking, communication between cognitive users need to use a s hared transmission control channel to complete the routing and signaling control information in one or more than one, so the design of routing protocol and MAC protocol need to consider the requirements of control channel. Cognitive radio technology because it can make full use of existing spectrum resources in wireless networks, since the application foreground is very good, but at the same time, due to the power limitation, wireless network itself, node mobility, topology and 264 Copyright ⓒ 2015 SERSC throughput and delay. If the routing adaptive process fails, then the SPEAR routing protocol from the source node to restart a new route establishment process.