a study on the spectrum efficient multi-hop wireless network

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The performance of a random media access such as CSMA/CA is characterized by throughput. Throughput has no unit and it is defined as the ratio of the average rate of packets successfully transmitted divided by the channel packet rate [5]. 1.2 Multi-hop Topology WMN is a wireless network adopting a multi-hop wireless technology without deployment of wired backhaul links. WMN is similar to Mobile Ad-hoc Networks (MANET); however, the nodes are relatively fixed. Another difference is that WMN can introduce hierarchy network architecture. Multi-hop networks are divided into two categories, relay and mesh. Relay (Flat Topology) is a tree based topology where one end of the path is the base station as shown in Fig 1.3. Figure 1.3: Relay multi-hop wireless network Mesh on the other hand has multiple connections between users as illustrated in Fig 1.4. Figure 1.4: Mesh multi-hop wireless network Multi-hop wireless networks have an advantage of rapid deployment, ease to provide coverage in hard to reach places, extend coverage due to multi-hop forwarding. The 3
more hops introduced, the less power required to transmit. In some cases, this could result in an increased battery life for users on mobile devices. Multi-hop is also known to introduce some challenges such as routing complexity and extra delay due to multi-hop. 1.3 Spectral efficiency Radio resources are scarce and expensive. In order to have an economically feasible system, the available resources must be used in an efficient way. In cellular systems, maximizing the number of users in each cell while maintaining an adequate level of Quality of Service (QoS); is the key to achieve efficient spectral optimization. In general, the spectrum efficiency is defined as the useful information (excluding overhead and control packets) that can be transmitted per second per bandwidth. It is the optimized use of spectrum or bandwidth so that the maximum amount of data can be transmitted with the least amount of transmission errors. It is also can be considered as a measure of how well the spectrum is utilized by the physical layer protocol or even the media access control. The spectral efficiency of a digital communication system is expressed in (bit/s)/Hz. It is the maximum throughput divided by the bandwidth in hertz of a communication channel or a data link. Consequently, the better maximum throughput and packet delivery achieved, the higher the spectrum efficiency is. The overall spectral efficiency of the system in (bit/s)/Hz is calculated using (1) [6] Overall . spectral . efficiency = Max. Throughput Bandwidth = KR W (Bits/s/Hz) (1) Where K is the number of users in the network of in the case of cellular networks, the number of users in the cell. R is the maximum throughput and W is the bandwidth of the system. From the equation we can conclude that’s more users served in the cell of the network, the better the overall spectral efficiency of the system. Moreover, improving the maximum throughput also will improve the overall spectral efficiency [6]. 4
Page 1: A STUDY ON THE SPECTRUM EFFICIENT M
Page 4 and 5: Copyright @ 2009 by WADHAH HAFIDH A
Page 6 and 7: 、上記条件下で、4 m/s
Page 8 and 9: The WMN experiments showed that the
Page 10 and 11: Table of Contents Abstract in Japan
Page 12 and 13: List of Figures Figure 1.1: Infrast
Page 14 and 15: List of Tables Table 2.1: Compariso
Page 16 and 17: CHAPTER 1 Introduction 1.1 IEEE 802
Page 20 and 21: 1.4 Interference problem Interferen
Page 22 and 23: On the other hand, the backbone net
Page 24 and 25: CHAPTER 2 Mobile Ad-hoc Network 2.1
Page 26 and 27: Route Request AODV Intermediate nod
Page 28 and 29: Request (RREQ) [4] in order to iden
Page 30 and 31: DATA Motion Figure 2.4: Higher mobi
Page 32 and 33: CHAPTER 3 Packet Delivery Rate (PDR
Page 34 and 35: Table 3.1: Simulation Parameters Pa
Page 36 and 37: oute stat hold time parameter in th
Page 38 and 39: speed values due to the ability of
Page 40 and 41: Figure 3.7:Coverage area and moveme
Page 42 and 43: Figure 3.8: Simulated Ad-hoc mobile
Page 44 and 45: Figure 3.9: Example of Convergence
Page 46 and 47: oute. This caused the 10m/s speed t
Page 48 and 49: Figure 3.14: Number of users vs. Me
Page 50 and 51: Figure 3.16: Simulated Ad-hoc mobil
Page 52 and 53: 3.9 Chapter summary Four simulation
Page 54 and 55: suppressing channel interference is
Page 56 and 57: The two radios provide the ability
Page 58 and 59: Figure 4.4: Interference in Multi-r
Page 60 and 61: Figure 4.6: Phase Shift and cancel
Page 62 and 63: As mentioned before, it was shown i
Page 64 and 65: Basically, the experiments are cate
Page 66 and 67: Figure 5.2: AirMagnet Surveyor inte
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The directional coupler is a passiv
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Figure 5.7: Throughput vs. SIR (Int
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Figure 5.10: Three hop WMN with two
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Table 5.2:Throughput of Mutli-hop W
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PathLoss ( dB) = 40 + [35log10 D( m
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Figure 5.17: Actual Interference ca
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Figure 5.20: Attenuation value vs.
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Figure 5.22 illustrates the S 21 pa
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link. The experimental results show
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Scenario A.1 This scenario simulate
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Destination address Table Table A.1
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Figure B.2: Attenuation value vs. t
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[10] S Gowrishankar, T G Basavaraju
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[32] Jing Zhu and Roy, S., “802.1
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