MAC Protocols Design for Multiple Antenna Based Cognitive Radio Wireless Mesh Network
| dc.contributor.advisor | Casademont Jordi (Professor) | |
| dc.contributor.author | Atlabachew Mulugeta | |
| dc.date.accessioned | 2019-09-26T07:29:33Z | |
| dc.date.accessioned | 2023-11-04T12:22:51Z | |
| dc.date.available | 2019-09-26T07:29:33Z | |
| dc.date.available | 2023-11-04T12:22:51Z | |
| dc.date.issued | 12/5/2018 | |
| dc.description.abstract | Different measurements show that most of the time, most of the usable spectrum bands are underutilized. To improve the utilization efficiency of this natural resource (spectrum), Cognitive Radio (CR) system has been proposed. One of the key elements of CR systems is the Dynamic Spectrum Management Unit (DSMU). The DSMU improves the performance of wireless systems by providing additional spectrum bands in an opportunistic manner from the legacy spectrum users. Whereas, the cognitive radio users should not produce a significant interference to these legacy users (Primary users) and must evacuate itself seamlessly from the spectrum band in the appearance of the primary user (s). Integrating the CR system with Wireless Mesh Network (WMN) alleviates the spectrum scarcity mindset that surfaces on the traditional WMN which operates in unlicensed spectrum band. Assimilating multiple antenna system with CR based WMN results multiple antenna based Cognitive Radio Wireless Mesh Network (CRWMN). In this dissertation, we design medium access control (MAC) protocols for CRWMN using both omin-directional and directional multiple antenna technology. The design of MAC protocol for CR requires the integration of the physical layer (spectrum sensing) with the MAC layer. After developing the closed form expressions for the saturated throughput and average packet delay for the proposed MAC protocols, MATLAB software is used to simulate and evaluate the proposed random access MAC protocols. There are three main contributions in this dissertation work. The first contribution is to examine the impact of multiple antenna systems on the performance of CRNS in terms of capacity, spectrum sensing and spectrum sharing. The investigation revealed that multiple antenna has significant advantages in terms of capacity improvement, range extension, energy efficiency, interference reduction, shorter spectrum sensing time, and better spectrum sharing efficiency. The second contribution of this dissertation is proposing an improved medium access mechanism called M-CTS (Modified Clear to Send) which eliminate one RTS frame and one SIFS slot from the RTS/CTS access mechanism during a successful transmission, and based MAC protocols Design for Multiple Antenna based Cognitive Radio Wireless Mesh Network ii on this access mechanism, a new random access MAC protocol called an enhanced random access MAC protocol for CRN (ECR-MAC) is proposed. The system model is developed for CRWMN using omni-directional antenna; and the performance of ECR-MAC has been analyzed using analytical model and simulated using MATLAB. Its performance in terms of throughput and average packet delay is evaluated for different number of secondary users, contention window size, and probability of transmission. The performance evaluations shows that ECR-MAC protocol exhibits good performance improvement compared with random access cognitive radio MAC protocols designed based on basic access and RTS/CTS access mechanisms. Compared with RTS/CTS based random access CR-MAC, ECR-MAC protocol shows at least five percent performance improvement. The third contributions of this dissertation work are proposing directional random access MAC protocols for CRN called DCR-MAC protocols. The proposed DCR-MAC protocols make use of three access mechanisms; these are BASIC, RTS/CTS, and M-CTS access mechanisms. The proposed DCR-MAC protocols use beamwidth, number of secondary users, contention window size, and probability of transmission as key parameters to evaluate the performance of the proposed directional MAC protocols in terms of average throughput and average packet delay. Closed form expressions for average throughput and average packet delay are developed for the DCR_MAC protocols. The performance investigation of the proposed DCR-MAC protocols (particularly M-CTS access) using simulations show good throughput performance improvement, which is more than 475% on average, in relative to omni-directional CR-MAC protocol (ECR-MAC). However, the DCR-MAC with M-CTS access mechanisms still shows a superior performance among the remaining two access mechanisms implemented in the DCR-MAC protocols. In general, the use of multiple antenna system for CRWMN improves the overall performance of the system. The proposed ECR-MAC protocol is promising for CRN in general and for CRWMN in particular in terms of throughput and average packet delay. The proposed directional CR-MAC protocols show remarkable performance improvement, however, equipping client nodes with multiple antenna is still a big challenge. | en_US |
| dc.identifier.uri | http://etd.aau.edu.et/handle/123456789/19172 | |
| dc.language.iso | en | en_US |
| dc.publisher | Addis Ababa University | en_US |
| dc.subject | MAC Protocols | en_US |
| dc.subject | Design | en_US |
| dc.subject | Multiple Antenna | en_US |
| dc.subject | Cognitive Radio | en_US |
| dc.subject | Wireless Mesh Network | en_US |
| dc.title | MAC Protocols Design for Multiple Antenna Based Cognitive Radio Wireless Mesh Network | en_US |
| dc.type | Thesis | en_US |