Mesh-Relay with MRC in 802.16j

Networks

MARIA JIMENA ARGUELLO BALTODANO

Master of Science ThesisStockholm, Sweden 2010

Mesh-Relay with MRC in 802.16j

Networks

MARIA JIMENA ARGUELLO BALTODANO

Master of Science Thesis performed at

the Radio Communication Systems Group, KTH.

August 2010

Examiner: Professor Ben Slimane

KTH School of Information and Communications Technology (ICT)Radio Communication Systems (RCS)

TRITA-ICT-EX-2010:193

c© Marıa Jimena Arguello Baltodano, August 2010

Tryck: Universitetsservice AB

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Abstract

Multi-hop relay networks are a recent trend in WiMAX 802.16j networks. Many studies on

the viability of relay stations have been done. It shows that RS are good cost-effective

solution to the increasing demands on wireless broadband services. One problem that faces

the 802.16j standard is its topology. It is a tree based multi-hop relay network, which is very

vulnerable to single point breakage. This thesis proposes a new robust pairing technique in

802.16j network; combining a mesh topology with maximal ratio combining at the access

link. Maximal ratio combining takes advantage of the broadcast nature of relay stations to

obtain diversity gain. Mesh topology is a more robust topology without increasing delay or

decreasing throughput. Maximal ratio combining provides higher throughput per burst,

together a total throughput is increase 5% per frame is achieved.

Acknowledgements

The completion of the thesis has been a rewarding experience. I’m most thankful for the

support of my loving husband, family and friends in Sweden, without their help it wouldn’t

be possible to complete this work. I would like to give thanks to my supervising professor

Ben Silmane for his help and feedback. I’m most grateful for KTH and Sweden for providing a

memorable experience during my master’s studies.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1 Problem Statement 1.2 Previous Work 2. 802.16j standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 2.1 RS types and characteristics 2.2 Frame Structure 2.3 Sub-Channels 2.4 MAC Layer 3. System Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.1 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 3.1.2 Assumptions

3.1.3 Frame Structure

3.1.4 OFDMA Calculation

3.1.5 Algorithm 3.2 Relay Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.2.1 Tree Topology

3.2.2 Mesh Topology 3.3 Access Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

3.3.1 Channel Model

3.3.1.1 Cost Hata Walfisch-Ikegami

3.3.1.2 WINNER II

3.3.2 Selection Diversity

3.3.3 Maximal Ratio Combining

4. Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.1 Delay 4.2 Throughput 4.3 Work Load 4.4 Service Rate 5. Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 5.1 Relay Zone 5.2 Access Zone

6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 6.1 Conclusion 6.2 Future Work 7. Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

8. Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

A. M-files

B. Routing Tables

C. Results

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List of Figures Figure 1.1 Relay topologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 2.1 TDD Frame Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 2.2 Non-transparent RS TTR frame structure 802.16j standard . . . . . . . . . . . . . . . . . . . 12

Figure 2.3 Sub-Carriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 2.4 Medium Access Control: Initial network entry and topology discovery . . . . . . . . . .14

Figure 3.1 RS Group allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 3.2 Frame Structure used in Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 3.3 Simulation Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 3.4 CDF of non-uniform traffic with w=2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 3.5 Example of a Tree Topology Routing Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 3.6 Example of a Mesh Topology Routing Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 3.7 Simulation Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Figure 3.8 Example of a Mesh Topology with MRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Figure 5.1 Non uniform buffer work load with w=2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 5.2 Mesh topology with non-uniform traffic distribution . . . . . . . . . . . . . . . . . . . . . . 30

Figure 5.3 Comparison between MRC and SD with different resource allocation schemes . . .31

List of Tables Table 3.1 Network Parameters Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Table 3.2 Frame Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Table 3.3 Links and path loss types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Table 5.1 Relay Zone performance measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Table 5.2 Performance Measurements SD and MRC with 1000 frame . . . . . . . . . . . . . . . . . . 32

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Abbreviations

� AAA Authentication Authorization and Accounting

� AC Authentication Control

� AK Authentication Key

� AMC Adaptive Modulation Coding

� ART Above Roof Top

� BRT Below Roof Top

� BW Bandwidth

� CDF Cumulative Distribution Function

� CID Connection ID

� CP Cyclic Prefix

� DL Downlink

� DL-MAP Downlink Access Definition message

� EAP Extensible Authentication Protocol

� FCH Frame Control Header

� FDD Frequency Division Duplex

� FFT Fast Fourier Transform

� LOS Line Of Sight

� MAC Media Access Control

� MATLAB Matrix Laboratory

� MR-BS Multi-hop Relay Base Station

� MRC Maximal Ratio Combining

� MS Mobile Station

� MSID Mobile Station ID

� NLOS Non Line Of Sight

� OFDM Orthogonal Frequency Division Multiplexing

� PDU Protocol Data Unit

� PMP Point to Multi-Point

� PUSC Partial Usage of Subcarriers � QoS Quality of Service

� R-DL Relay Downlink

� R-FCH Relay Zone Frame Control Header

� R-MAP Relay Zone MAP

� R-RTI Relay Receive/Transmit Transition Interval

� RS Relay Station

� RSID Relay Station Identification

� RTG Receive/Transmit Transition Gap

� R-TTI Relay Transmit/Receive Transition Interval

� R-UL Relay Uplink

� R-Zone Relay Zone

� SD Selection Diversity

� SNR Signal to Noise Ratio

� STR Simultaneous Transmits and Receives Relaying

� TDD Time Division Duplex

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� TLS Transport Layer Security

� TTG Transmit/Receive Transition Gap

� UL Uplink

� UL-MAP Uplink Access Definition message

� WiMAX Worldwide Interoperability for Microwave Access

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1. Introduction

June 2009 the WiMAX (Worldwide Interoperability for Microwave Access) 802.16j standard

was published and uses relay stations (RS) to enhance 802.16e coverage and capacity [1]

[14]. A RS is an equipment set that is under supervision of a multi-hop relay base station

(MR-BS) and connects to other RSs, mobile stations (MS) or MR-BS. It can also provide

management and network access to child RSs or MS.

Many studies on the viability of RS have been done [2]. It shows that RS are good cost-

effective solution to the increasing demands on wireless broadband services in 4G networks.

They are cheap mass produced devices with low power consumption. RS are easy to install

and don’t require expensive towers. They can be mounted on lamp post, signs or on

building.

1.1 Problem Statement

A difficulty that faces the 802.16j standard is its topology. It is a tree based (Point to Multi-

point, PMP) multi-hop relay network therefore a single point of breakage can leave network

unstable. This is more evident in large coverage cells where there exist more than two hops.

RS are not as robust as a MR-BS consequently, if a RS at the first tier is broken or a

bottleneck occurs, this leaves a whole branch without communication. The tree based

topology is vulnerable in large coverage networks and careful resource allocation is need in a

tree topology to ensure a constant uniform traffic flow over the whole network.

Mesh relay networks are robust and effective solution to meet capacity and coverage

requirements in large networks consisting of more than two hops. Mesh relays can

communicate with many immediate relays and select the best link to relay packets. Mesh

relays regularly broadcast neighbor lists. These lists contain: link quality, traffic load, hop

distance and control slot information that will be used to gain access and relay packets to

the route with least delays and higher signal to noise ratio (SNR). The MR-BS is part of a

neighborhood domain and the relays within this cell help transfer packets from their

neighbor relay towards their destination MS using a dynamic routing algorithm. This key

feature is what makes mesh topology more robust and efficient. An example of both

topologies is shown in figure 1.1. It can be seen that the tree topology has one route for

uplink or downlink traffic flow, where the mesh topology has at least two routes with same

hop count to cell border RSs.

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Figure 1.1: Relay topologies

A cooperative network is needed that doesn’t produce too much redundancy and provide

robustness at the access link, where higher shadow fading occurs and to take advantage of

the broadcast nature of RSs. In a typical cooperative relays network, in every hop a RS send

two or more copies of a single signal. This is not an effective way to use the spectrum. High

diversity gain can be achieved when it is in order of two or three. More than this the

resulting SNR doesn’t improve much [2]. This redundancy also increases congestion and

delays in large relay networks with more than two hops.

This thesis proposes a new robust pairing technique in 802.16j network; combining a mesh

topology with cooperative scheme at the access link. The mesh topology uses same frame

structure and parameters as the 802.16j standard to insure compatibility. The scheme takes

advantage of the characteristics of RS broadcast nature to achieve diversity gain using

maximal ratio combining (MRC). RSs are fixed therefore RS mesh scheduling schemes are

much simpler than mobile mesh MS. This allows better channel allocation and therefore

lower intra-cell interference is achieved by using frequency reuse factor of 1/3. With

simulations of different network schemes mention above, this thesis intends to resolve

inquiries like: Is a mesh topology is more efficient than the tree topology used by the

standard? Can large coverage requirements be achieved without sacrificing throughput and

increase delay? How stable is mesh network under non-uniform traffic distribution? Does

maximal ratio combining increase total network throughput over selection diversity and if so

are there any drawbacks?

Mesh Tree

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1.2 Previous Work

Multi-hop relay networks are a recent trend in cellular networks. Many publications have

been done in this topic. Most research has focus in small network consisting of less than two

hops, with good performance measurements with different topology configurations,

scheduling schemes and relay stations; some better than other.

Papers based on the 802.16j standard are analyzed [3], [4] and [5]. These papers are all tree

topology with different configurations and scheduling schemes of small networks of 2 hops

at most. In previous work [3] two types of scheduling schemes are evaluated: centralized

and distributed. The distributed scheme had less overhead and information exchanged than

the centralized scheme. A MS is scheduled to one relay station or MR-BS, using best channel

selection this is selection diversity (SD). RS with one MS are given priority over other RS with

more than one access link request. In the distributed scheme a common slotted

communication channel is shared by all RS. Each RS randomly selects a slot if collision

happens a retransmission is performed in second paring section. No “child relay” is

evaluated, max 2 hops from MS to MR-BS. Both schemes achieved higher cell throughput

and more MSs served compared to random and opportunistic scheduling. Delay is

introduced using this type of scheduling technique, RS due to retransmission.

In paper [4] focuses on adaptive scheduling for prioritized traffic using a centralized model.

In the non-transparent relays the uplink sub-frame is divided into access zone and relay

zone. The relay zone is divided odd and even relays so that the relay station can receive or

transmit at a time. This division is based on bandwidth (BW) demand, number of MSs and

relays and the conditions of sub-channels of a link. The BS allocates slots for all MSs and RS.

Much research has been done on cooperative relay. Higher throughputs or diversity gains

are achieved in small 2 hop networks. In paper [6] two copies are relayed between node

(parallel relay network). It uses decode and forward with beamforming. For large networks

this results impractical since every hop the number of bursts transmits double, therefore

using double more resources. Diversity gain doesn’t increase linearly with order. Having

more than three copies of the same burst doesn’t improve SNR received.

Mesh client relay network improves network performances in [7] and [8]. A hybrid PMP-

Mesh topology is used in [7]. The relays in are connected in a PMP configuration to the MR-

BS. RS are located at cell edge to add coverage. Mobile mesh clients have high overheads

exchange in reserving resources and quality of service (QoS) parameters. Scheduling is very

important in the assurance of QoS in mobile mesh clients. Paper [8] uses an algorithm with

path discovery, resource allocation and path selection for a dynamic relay network. Quasi-

stationary router are used has a backbone to decrease overhead.

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2. 802.16j Standard

2.1 Relay Station Types and Characteristics

The standard is flexible, it has many types of RSs depending on the mobility, capacity and

coverage demands. There are two types of relay modes from the physical processing

perspective: transparent and non-transparent relays [9]. In transparent relays the MSs are

not aware of the existence of the RSs. The RS relays only data traffic and works with

centralized scheduling only. It is a good cost effective solution to improve throughput in cells

and MS minimize power consumption in fixed or nomadic applications. In non-transparent

RS, it transmits preamble and other broadcast messages as well as data traffic therefore,

expanding coverage but at the cost of increased signaling overhead latency.

WiMAX 802.16j has two scheduling modes: centralized and distributed. In the centralized

mode the MR-BS allocates the bandwidth for all RSs and MSs in the cell and generates

corresponding channel MAPs. All information regarding the access link of a MS’s channel

measurements and bandwidth requirements are forwarded through the RS to the BS. The

distributed modes allow each RS to allocate bandwidths to subordinate MSs and RSs. The RS

is under supervision of MR-BS and the MR-BS has full knowledge of all MS in the network.

This mode maximizes bandwidth efficiency by optimizing packet size and provides full

support for MS mobility.

Three relay transmission schemes are used: amplify and forward, selective decode and

forward and demodulation and forward. Selective decode and forward is the best choice,

high throughput and low delay with low SNR. [4] Demodulate and forward offers best

throughput but processing time is too high increasing delay in the network. Amplify and

forward in cases of low SNR increases noise levels.

2.2 Frame Structure

Two main relay mechanisms are proposed in the 802.16j standard: simultaneous transmit

and receive (STR) relaying and time-division transmit and receive (TTR) relaying. The STR

relay mechanism is used in frequency division duplex (FDD) mode. The transmissions to

child relay and reception from parent relay or MR-BS or vice versa are performed

simultaneously in different channels. TTR relay mechanism is used in time division duplex

(TDD) mode. In this case the transmission to child relays and receptions from parent relays

or vice versa are separated in time [10]. One advantage of using TTR frame is that uplink or

downlink zones can be easily adjusted to meet the traffic demands of uplink and downlink.

Figure 2.1 shows the TTR frame structure used in the standard.

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Figure2.1: TDD Frame Structure

The 802.16j is backwards compatible with 802.16e. The MR-BS and RSs is either transmitting

or receiving. There are two types of frames odd and even frames. A TTR relay station can

either perform relaying on the same carrier frequency or on a separate carrier frequency,

depending on frequency planning, by time dividing communication with the child RSs and

parent RSs.

The TTR frame is shown in the figure 2.2 for non-transparent RSs. Both odd and even frames

are time aligned and split into access and relay zones. The access zones in uplink and

downlink are for MS to communicate to either a RS or MR-BS that access them to the

network. The relay zone is for RSs and MR-BS to communicate with each other.

Even frames have two transmission gaps: transmit/receive transition gap (TTG) and receive /

transmit transition gap (RTG) in which the radio equipment switches from transmitter to

receiver mode and vice versa. The odd frames have same two gaps: TTG and RTG; and two

intervals: relay transmit/receive transition interval (R-TTI) and relay receive / transmit

transition interval (R-RTI) [9] each are length n integer symbols.

The preamble is located at the beginning of the frame followed by frame control header

(FCH) and Downlink MAP (DL-MAP). They are position in same manner as the 802.16e

standard. The preamble is one symbol long. The receiver uses the preamble to synchronize

and to estimate frequency and phase errors. The FCH is two symbols long and is in a fixed

position. It describes the sub-channels used, the length of DL-MAP and transmission

parameters. The uplink MAP (UL-MAP) and the DL-MAP describes the location, number and

size of the bursts. The UL-MAP is transmitted in the first burst in the downlink access zone

[10]. The uplink ranging is for the MS to perform frequency and power adjustments, and

bandwidth requests

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Figure 2.2: Non-transparent RS TTR frame structure 802.16j standard

All RS must be synchronized through air interface. The relay amble is used to perform allow

child RS to track parent RS or MR-BS synchronization. Child RS adjusts frequency and time

alignment with the rest of the network. It doesn’t appear in every frame and it’s

configurable.

2.3 Sub-Channels

Orthogonal Frequency Division Multiple Access (OFDMA) divides the spectrum in equally

spaced tones or sub-carriers with guard bands between each carrier. The number of sub-

carriers is equal to the fast Fourier transform (FFT) size and it can be: 2048, 1024, 512 or 128

with system channel bandwidth 20, 10, 5, and 1.25 MHz respectively. The FFT size should be

chosen carefully to balance multipath, Doppler shift and design cost and complexity. Large

FFT size reduces subcarrier spacing and increases symbol time, this is good for multipath but

bad for inter-carrier interference. Each sub-carrier is orthogonal transmission and the sub-

channels overlap in time therefore reducing spectrum use. The nominal channel bandwidth

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has two guards at both ends of the spectrum and of length 1/4, 1/8, 1/16 or 1/32 of nominal

bandwidth.

Three types of sub-carriers are used in OFDMA: data, pilot and null subcarriers. Data sub-

carriers have information symbols. Pilot sub-carriers send known symbols and are used for

tracking various effects. The null sub-carriers are used as guard bands. Active sub-carriers

are group into sub-channels.

In OFDMA there are two types of sub-channelization: diversity and contiguous. A sub-

channel is formed by randomly selected sub-carriers provide frequency diversity is called

partial usage of subcarriers (PUSC). The contiguous scheme groups adjacent sub-carriers to

form a sub-channel; this scheme is called adaptive modulation coding (AMC). This scheme

exploits multiuser diversity, allocating sub-channels based on frequency response,

maximizing received signal to interference and noise ratio (SINR). The diversity scheme is

well suited for mobile application while the contiguous schemes for fixed and low mobility

applications.

The smallest unit of resource unit in the frame is a slot. A slot has M*N=6 (bins*symbol).

Each bin has 9 sub carriers (8data and 1 pilot sub carrier). One sub-channel contains two

clusters of 4 pilot carriers and 24 data carriers (52 sub carriers in total) or 6 bins. Sub-carriers

are grouped continuously (adjacent sub-carrier permutation).

OFDMA symbols have cyclic prefix (CP) used as guard intervals to remove inter-symbol

interference ISI. The length of this guard depends on the maximum expected delay spread of

the channel. CP guard is typically: 1/4, 1/8, 1/16 and 1/32. The CP is usually a repetition of

the last data samples of the previous block. This guard decreases bandwidth and power

efficiency as a result, larger symbol period increases efficiency.

Figure 2.3 Sub-Carriers

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2.4 MAC Layer

The MR-BS needs to know the access link of every MS in its cell. This topology discovery is

performed during the MS network entry. Figure 2.3 demonstrates this procedure. It has four

fundamental steps: local transmission and parameter adjustments, Admission Control,

topology discovery and data relaying.

Figure 2.4: Medium Access Control: Initial network entry and topology discovery

In mobile connection identification (MS-CID) based routing packets are forwarded based on

the connection identification (CID) of the destination station. CIDs are managed and

assigned by an MR-BS. Path management can be done two ways: embedded and explicit.

The embedded path management approach uses a hierarchical CID allocation scheme in the

system. There is no routing table in each RS. The BS allocates CIDs to its child RS and these

15

allocates sub sets CIDs to child RSs and so forth. The explicit path management approach

requires the BS to have information involving all RS in the path. Each path is identified by a

path ID to which the CIDs are bound. This scheme has smaller routing tables and a decrease

of overhead to update tables.

The IEEE 802.16j uses the same authentication protocol as 802.16e. Extensible

Authentication Protocol (EAP) and Transport Layer Security (TLS) are exchanged between an

MS and an Authentication Authorization and Accounting (AAA) server. Next the MR-BS and

the MS generates an authentication key (AK) derived from EAP authentication. The MR-BS

sends this key with an encrypted RS key to the MS and a three way handshake is performed

to confirm that they share same security secret. [10]

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Odd Relays Even Relays

3. System Model

The main goal of this thesis is to find a more efficient topology and diversity scheme. In the

first part a comparison is made between tree and mesh topology to check robustness, delay

and fairness with a non-uniform traffic distribution. The second part uses maximal ratio

combining in the access link and compare it with selection diversity. Which topology resolves

fairness, robustness and delay requires better? Does MRC scheme introduce delay and how

much can be gained in service rate and total throughput? These are some the questions that

are tried to answer using the following method.

3.1 Assumptions

Before starting, some assumption needed to be made regarding: RS allocation, channel

modeling, frame and network parameters. Matrix Laboratory (MATLAB) software networks

simulations are used to evaluate the different topologies and diversity schemes. Relay

stations are assumed to be equidistant and placed in a hexagonal grid. This grid is used

because of its simplicity and even coverage of the cell. MR-BS and RS have Omni-directional

antennas. The RS and MR-BS are either transmission or receiver mode (TTR frame is used).

All the antennas in Rs and MR-Bs have same transmitting power, pattern and gain.

RSs are divided into even and odd nodes depending on the hop count from MR-BS. The MR-

BS is even and the second tiers of RSs are odd and so forth. Even and odd nodes are divided

in three groups. RSs and MR-BS from the same group are not adjacent; this is done to

minimized interference between them. In figure 3.1 the group allocation is shown for odd

and even nodes. There are 6 groups in total, [1-3] are even and [4-6] are the odd groups.

MR-BS belongs to group 1 the rest of the groups are all RSs.

Figure 3.1: RS Group allocation

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Parameter setting, network configuration and routing tables are resolved before the

network simulation begins. The parameter settings used in the simulation are showed in

table 3.2. RS position and parameters settings are the same for mesh and tree topology but

routing table and relay algorithm differ for both topologies.

Table 3.1: Network Parameter Settings

3.1.1 Frame structure

Like in the 802.16j frame odd and even frames are time aligned. The access and relay zones

start at the same time. Instead of dividing relay zones in uplink and downlink. In this thesis

the relay zone is divided into odd and even groups. Even RS relay bursts in the first half and

odd RS in the second half. Consequently, RSs doesn’t distinguish between uplink or down

link relays. This way RSs are never idle, they are transmitting or receiving bursts. The frame

structure used in this thesis is shown below in figure 3.2.

Allocating resources or slots is very important for network performance measurements. In

figure 1, the mesh network topology is shown. The highest work load is allocated at the

center of the network, given that bursts are relayed uplink or downlink. It can be seen that

the MR-BS sends bursts to three RSs and these RSs relays to two RSs. Therefore odd relay

requires one third of the resources of MR-BS and the second tier of RSs requires half of the

first tier RSs. Using this logic we can say that:

If lambda is the number of burst arrived at MR-BS and Y is the total number of bursts that

can be allocated at the Relay Zone, then:

Lambda+ (1/6*lambda)*2+ (1/3*lambda)*3 =Y Therefore lambda=round(Y*(3/7)) Where,

lambda is an integer. The relay zone resource allocation is given by:

Even Relay group = round (1/6 *lambda)

Odd Relay group= round (1/3*lambda)

Parameter Value

BS transmit power 37dBm

RS transmit power 37dBm

BS-RS shadowing effect 3

BS-MS, RS-MS shadowing effect 8

BS antenna gain 15dB

RS antenna gain 15dB

MS antenna gain Omni /-1dBi

Noise power -174dBm/Hz

BS height 30m

RS height 10m

MS height 1.5m

Number of RS 45

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Figure 3.2: Frame Structure used in Simulations

3.1.2 OFDMA Calculation

For the simulation 2048 subcarriers (FFT of size 2048) with a 20MHz of BW is assumed. Only

1680 sub-carriers are used with guard bands of 1/16 each (183 null guard sub-carriers at the

right and 184 null sub-carriers at the left) and a null carrier (DC carrier) located at the center

transmission frequency. This leaves 1440 data sub-carriers and 240 pilot sub-carriers, which

are 30 sub-channels. One sub-channel is equal to 6 bins. In this simulation a slot (N x M) =

(6x1) 6bins x 1 symbol, is considered. [11]

Table 3.2: Frame Parameters

Sampling frequency Fs = n* BW = 22.4MHz

Where, n is a sampling

factor

given by: n= Fs/BW

Subcarrier spacing Δf = Fs/ NFFT =10.94kHz

Useful symbol Time Tb= 1/ Δf = 91.42µs

Cyclic Prefix Time Tg = G* Tb = 22.85µs

OFDMA Symbol

Time

Ts = Tb + Tg = 114µs

Number of symbols Nsym=floor (T/ Ts) = 87

Parameter Value

Bandwidth 20MHz

NFFT 2048

Sub-channels 30

Symbols per frame 175

Frame duration T 10 ms

Sampling factor n 25/28

BW guard 1/8

CP guard G 1/4

Modulation QPSK

Slot (N*M) 6*1

Transmit Mode

Gro

up

1

Gro

up

2

Gro

up

3

R-M

AP

R

FC

H

FC

H

DL-

MA

P

Pre

am

ble

OFDMA Symbols

Raging Sub Ch Raging Sub Ch

UL Access Zone Receiver

Mode TT

G

RT

G

FC

H

DL-

MA

P

Pre

am

ble

Access Zone Relay Zone Access Zone Relay Zone

Transmit

Mode Receiver Mode

Raging Sub

channel FC

H

DL-

MA

P

Pre

am

ble

FC

H

R-T

TI

TT

G

UL Access

Zone

R-R

TI

RT

G

Gro

up

4

Gro

up

5

Gro

up

6

Pre

am

ble

DL-

MA

P

Od

d F

ram

e S

ub

-ch

an

ne

l E

ve

n F

ram

e S

ub

-ch

an

ne

l

19

Which leaves 79 useful symbols for access and relay zones, 79*30 slots. A burst is a group of

packets for a singles user. In WiMAX burst vary in length. For simplification purposes burst

are consider of size 12 slots. Relay and Access zone have= (79*30)/12=197 bursts in total.

3.1.3 Algorithm

Simulation starts with traffic generation at the MR-BS. Bursts are generated with an arrival

rate lambda. Each burst is allocated a destination relay station identification (RSID) used in

[12]. The packet data unit (PDU) in relay zone carries a destination RSID in the sub header, of

16 bits. Each RS in the downlink path receives and checks routing table and relays a copy of

the burst to the next RS. Burst received go to a buffer and wait for transmission. Bursts are

relay in first in first out (FIFO) bases to the next RS. A maximum of Nmax bursts can be

during it group relay zone. The rest of the bursts not transmitted wait for next frame to be

selected for transmission. The size of burst waiting to be transmitted is called buffer work

load. The routing table and relaying algorithm depends on network topology. With a tree

topology relay route doesn’t change for a destination RS, where the mesh topology will

depend on traffic load at neighboring RS and hop count to destination RS, more details is

showed in section 3.2.

Once the destination RS receives the burst, it relays it destination MS during the access zone.

The access zone is divided into 6 groups each transmit respective group zone. A maximum of

Nmax bursts are transmitted during the access zone to destination MS. All groups have same

Nmax value in access zone. Downlink scenarios are simulated, therefore broadcast mode is

used at access link. The MS checks if MSID in the received PDU from RS, if it matches his

MSID, it retains the PDU. Two schemes are used in this thesis SD and MRC. In the MRC the

MS receives two copies of the burst from two RSs and SD only one copy is received. This is

further explained in section 3.3. The general algorithm is shown below in figure3.3.

Usable symbol calculation: Preamble 1 symbol

DL-MAP and FCH 2 symbols

R-TTI and R-RTI 2 symbols

TTG and RTG 2 symbols

UL-MAP 1symbol

Total 8

symbols,

20

RS routing tables

(Mesh or Tree

topology)

Simulation starts:

For every frame generate

traffic with poison distribution

lambda (at MR_BS) with a

destination RSID for Nth

frames. It can be uniform and

non-uniform distribution

(Figure 3.4 CDF)

All N frame are

simulated:

Performance

measurements

calculation and graphs

DL transmission starts in

frames.

1-Access Zone

2-Relay Zone: Even and odd

groups. Looks up routing table

to find next relay hop and Tx

[Nmax (group)] burst FIFO.

Network

configuration

Parameter

setting

(table3.1)

For every frame

buffer size is

updated.

If packet is

delivered to

destination RSID,

hop count, delay

and throughput

are calculated

Buffer size and

work load Tables

Network

Stable: Cell

border RSs

Rx burst

Figure 3.3: Algorithm

3.2 Relay Zone

Snap shot simulation were performed. MS are assumed to be known at the MR-Bs and its

access link, in other words initial network entry and topology for a MS are assumed to be

completed. The simulations input variables: maximum number of burst transmitted per

frame for each group (Nmax) and arrival rate for each frame lambda are the same for both

topologies. Nmax is a vector of length 6; first 3 values of vector Nmax correspond to the

even nodes and the rest are odd node maximum burst that can be relayed in one frame for

each group. The RS burst arrival rates are model as independent poison processes with

lambda equal to Nmax (1), full capacity is simulated. The MR-BS has Nmax (1) maximum

bursts to transmit in even relay zone and the other even RS Nmax (2, 3). The odd RS have

Nmax (4, 6) in relay zone. Network is at full capacity more than Nmax (1) will generate a

bottle neck at MR-BS.

In the access zone all RS have a maximum of N bursts to transmit to MSs in every frame. All

access link have the same maximum, therefore the access zone has a total of N burst*6

groups, bursts allocations in a frame period. Given channel reuse, the maximum network

service rate possible is: N max burst per group*46 RSs and MR-BS.

Two traffic scenarios are model uniform and non-uniform. In the non-uniform distribution

RSs 24, 7, 18, 28, 13, 27 and 4 are give w times the probability of having a burst than the

rest. This scheme shows how the mesh topology handles bottle necks in comparison with

21

tree topology. In figure 3.4 shows the Cumulative Distribution Function (CDF) of traffic with

w=2, RSs 24, 7, 18, 28, 13, 27 and 4 receive double more traffic than the rest of the

network´s RSs. RS 1 is the MR_BS and the rest are RSs. In figure 3.5 there allocation in

network can be seen.

Figure 3.4: CDF of non-uniform traffic with w=2

3.2.1 Tree Topology

All the RSs in network have information from neighboring RS regarding channel condition

and work load. All RS-RS link and BS-RS link are assumed to have same transmission rate. RSs

buffers are infinite; therefore bursts are never lost due to delay. Burst retransmission due to

delay or lost are not taken into account.

A RS has a table of hop distance of all RS and MS-RS. This routing table doesn’t changes

since RSs are fixed. Rs cannot receive and transmit simultaneously. Each Node will store

arriving packets in an infinite capacity buffer until they transmitted. There is a maximum of

three possible neighboring RS. One uplink and one or two downlink neighbor RS. Each

destination RS has one unique relay path from MRS-BS. The tree topology has 3 main

branches with equal amount of child RS. An example of a RS routing table is given in figure

3.5. From the RS8 routing table, it shows next relay hop for every destination RS in same

branch. RS8 receives a burst with a RSID, looks up destination RSID and relays burst in a first

in first out basis to next neighboring RS in its corresponding group zone. For the case RS8, it

receives burst from RS23 (odd relay zone) in downlink and relays to RS32 and RS 46 (even

relay zone).

CD

F

22

RS 8 Routing Table

1

20

22

21

3

2

7

6

5

4

26

27

28

29

30

31

24

23

25 11

12

13

14

15

16

25

9

8

27

26

10

39

38

37

36

35

43

42

41

40

32

44

33

46

45

34

Figure 3.5: Example of a Tree Topology Routing Table

3.2.2 Mesh Topology

Each RS as two routing table the next hop and number of hop table that doesn´t change and

the buffer size table updates every N frames. Route selection is given by two criteria: hop

count to destination RS and work load of neighboring RSs. The next RS will be the neighbor

RS with the minimum sum of hop count and work load value. The work load value is the

buffer size divided by the maximum bursts (Nmax (group)) that can be transmitted in that

frame for its group. It is not a full mesh topology, a maximum of 3 neighboring RSs are

available for the next hop selection. An example of a RS8 routing table is given in figure 3.6.

The routing table contains the hop count of all RSs in the network. The RS 8 has three

neighboring RS: 27, 32 and 46. RS 32 is at cell border, therefore is connected to RS8 only. All

uplink and downlink traffic is through RS 32. The shortest route from MR-BS is through RS

23, therefore most of the traffic with destination RS8 will pass through RS23 like the tree

topology unless; there is a bottleneck or link damage.

Destination Next Hop

1 23

2 23

20 23

23 23

24 23

32 32

23

RS 8 Routing Table

32

44

46

45

1

20

22

21

3

2

7

6

5

4

26

27

28

29

30

31

24

23

25 11

12

13

14

15

1

6

17

9

8

19

18

10

39

38

37

36

35

43 41

40

33

34

42

Like the tree, the RSs have information regarding neighboring RSs only and transmit state

information only to them. Admission control and MSID are transmitted to MR-BS in control

channels same as the 802.16j standard.

Figure 3.6: Example of a Mesh Topology Routing Table

3.3 Access Zone

The access zone simulations evaluate two types of diversity schemes: Selection Diversity (SD)

and Maximal Ratio Combining (MRC). A uniform traffic distribution is used with a mesh

topology for both schemes on a hexagonal grid. This part intends determine which access

link scheme works best. Delay, throughput, service rate and work load are evaluated and

compared for both schemes.

Maximal ratio combining and selection diversity requires different resource allocation in

access and relay zones. The simulations evaluate different resource allocations for MRC and

SD with 100 frames. This is due that some resource allocations have rapid bottlenecks. Later

a resource allocation is selected with the best performance for each and compares the

performance measurements with 1000 frame duration.

Neighboring RS

23

32

46

Hop Count to destination RSID for each branch

Destination

RSID RS23 RS32 RS46

1 4 6

2 2 4

3 4 6

4 6 8

5 6 8

…

32 1

…

45 5 3

46 5 1

24

3.3.1 Channel Model

The channel model used is the proposed by the IEEE working group. [13][14] There are 9

categories of path loss types and 4 application of model usage. This thesis uses type E and

Type F with usage Ⅰ, Ⅲ, Ⅳ; described below: Ⅰ. Fixed Infrastructure Usage Model Ⅱ. In-Building Coverage Usage Model Ⅲ. Temporary Coverage Usage Model Ⅳ. Coverage on Mobile Vehicle Usage Model

Table 3.3: Links and path loss types

Type E model is for a macro- cell suburban non-line of sight (NLOS) link that with antennas

above rooftop (ART) to below roof top (BRT). Type F model is for urban or suburban with line

of sight LOS or NLOS links with both antennas below roof top.

3.3.1.1 Cost Hata Walfisch-Ikegami

Links BS-MS use type E model. It’s a flat urban NLOS environment with uniform building

height. The BS antenna is above roof top and MS and RS antennas are below roof tops. The

COST 231 Walfisch-Ikegami model [13] is recommended with parameter values used below:

Street width, w = 20m (this is the spacing between building faces)

Street orientation angle= 90degrees

Rooftop height, ho= 20m

MS height, hm=1.5m

MR-BS height, hb=30m

RS height, hr=10m

Links Path-Loss

Type

Applicable

Usage Model

Note

BS-RS Type E Ⅰ, Ⅲ, Ⅳ Urban, BS antenna is ART

and RS antenna is BRT

BS-Ms Type E Ⅰ, Ⅲ, Ⅳ

BS antenna is ART

RS-RS Type F Ⅰ, Ⅲ, Ⅳ

Both RS antennas are BRT

RS-MS Type F Ⅰ, Ⅲ, Ⅳ

RS antenna is BRT

25

RS cell radius, Rmax=5Km

The total path loss is given by sum of three terms [dB]: free space path loss (LFS), rooftop to

street diffraction loss (LSD) and multi-diffraction loss (LMSD). The free space path loss term

is given by: LFS= 32.4 + 20*log(R) + 20*log (f),

Where, R is the distance between BS and MS in Km and f the carrier frequency in MHz. R is a

uniform random value between (0 and Rmax). The carrier frequency f is 2500 MHz.

The single rooftop to street diffraction loss is given by:

LSD = -16.9 -10*log (w) + 10*log (f) + 20*log (ho-hm) + LQ

Where, LQ = 4-0.114*(90-55)

The multi-diffraction loss is given by:

LMSD= -18*log (1+ (hb- ho)) + 54 + 18*log (R) + (-4+0.7*(f/925-1))* log (f) -9*log (w*2),

medium sized city is assumed in the simulation.

3.3.1.2 WINNER II

Links RS-MS use type F model. NLOS and urban setting is assumed. The Berg model is

proposed in [14] but too complicated; it requires a detailed map of building. The NLOS

winner model is used instead. [15] The WINNER model can be applied in the frequency

range from 2 – 6 GHz and for different antenna heights. B1 category is used in this

simulation. It is for urban micro-cells with both MS and Rs antennas below rooftop

For LOS the path loss (PL) is given below for 10m< d1<dBP and d2 <w/2, with , where

dBP is the break point distance and it is given by:

dBP = 4*(hr-1)*(hm-1)*f/c Where c is the propagation velocity in free space = 3*10^8,

therefore

PL= 22.7*log 10(d1 [m]) + 41.0 + 20*log 10(f [GHz]/5)

For dBP <d1<5Km and with , the path loss is given by:

PL= 40.00*log 10(d1) + 9.45-17.3*log10 (hr)-17.3log10 (hm) +2.7*log10 (f/5) For NLOS the

path loss is given below for 10m<d1<5km, w/2<d2<2km and . The parameter d1 is the

distance along the main street in meters and d2 is the distance for perpendicular Street

PL=min (PL (d1, d2), PL (d2, d1))

Where, PL (dk, dl) =PLLOS (dk) +20 -12.5*nj + 10*nj*log10 (dl) + 3*log10 (f/5)

And nj = max (2.8-0.0024*dk, 1.84)

26

Figure 3.7: Simulation Model

3.3.2 Selection Diversity

The 802.16j standard uses selection combining in the access link. The MS connects to the RS

or MR-BS with highest SNR. Initial network entry and topology discovery are not simulated

but assumed realized. Each burst transmitted in downlink has its corresponding RSID

destination and MSID. MS are assumed to be connected to the neighboring RS with highest

SNR at a maximum distance of Rmax, which is the cell radius of the RS.

This portion of simulation uses mesh topology, therefore same routing tables are used to

relay burst to destination RSID and later to the MS. Throughput, service rate and hop count

are calculated after access link transmission for each burst transmitted to a MS later these

values are compared with maximum ratio combining scheme.

w

hb

ho

d2

d1 d2

hm hr

hb

w

MS

RS

MR-BS

27

MS Access links with

MRC

1

20

22

21

3

2

7

6

5

4

26

27

28

29

30

31

24

23

25 11

12

13

14

15

16

17

9

8

19

18

10

39

38

37

36

35

43 41

40

32

44

33

46

45

34

42

a b

c

3.3.3 Maximal Ratio Combining

With maximal ratio combining in the access link, each MS receives two burst from different

RSs or MR-BS. The MS connects to the two nodes with highest SNR. Each copy of the burst is

combined with a gain factor proportional to its own SNR. The resulting received SNR is the

sum of the two links SNR’s. [16] In figure 3.8 an example of RS8 is shown. MS (a) is

connected to RS 23 and RS 8. The burst are relayed to RSID1 (in this case is RS 23). When RS

23 receives the burst, it relays it to RS 8. In the next access zone both transmits a copy to the

MS. The MS performs MRC with both signals received from RS 8 and RS 23. The resulting

received SNR is the sum of both signals received.

Two RSIDs are assigned to each burst. The RSID with least amount of hops is RSID1 and the

other is RSID2. The MS is located an r distance from each RS or MR-BS. The simulation

chooses r randomly with a uniform distribution from (0, Rmax]. The burst is relayed to

destination RSID1, when it receives the burst it transmit a copy to RSID2. The burst is

transmitted in the same access zone in different groups. The M-file algorithms are shown in

appendix part A for both SD and MRC.

MS RSID 1 RSID 2

a 23 8

b 8 32

c 8 46

Figure 3.8: Example of a Mesh Topology with MRC

28

4 Performance

4.1 Delay

The delay evaluated in these simulations is the frame count from when the burst was

generated to the frame the burst was transmitted to the MS in access zone. This delay does

not account for the delay in the access link channel. The delay is averaged over all burst

transmitted in access zone for each frame. Later it’s averaged over all N frames.

4.2 Throughput

The nominal bandwidth is 20MHz. With guards we have 16.406MHz of used bandwidth,

which is 546.8 KHz per sub-channel. There are 30 usable sub-channels in a frame. One slot is

equal to 1sub-channel (6bins)*1 symbol and one burst is equal to 12 slots. Therefore the

smallest bandwidth of a burst is 546.8 KHz and the largest is 6.561 MHz. This depends on the

grouping of slots in the burst. The lower bound is calculated in this simulation.

3.3 Work load

Each RS and MR-BS has a buffer with burst waiting for relaying to other RS or for

transmitting to MS. In the simulation the buffer size of every RS and MR-BS are evaluated in

every frame. This is done in order to see bottlenecks especially in non-uniform traffic.

3.4 Service Rate

The service rate is the amount of bursts transmitted to MSs during a frame period. It

averaged over N frames. This parameter is important it determines how many MS get

service during a frame. Larger the service rate more fairness in the network.

29

5 Results

5.1 Relay Zone

The tree and mesh topology are compared with uniform traffic and resource allocation: 2

Access Zone and 74, 12 and 12 even Relay groups and 25 in odd relay groups. This resource

allocation configuration gives the highest performance for both topologies. Table 5.1 shows

the results from this 100 simulation with 10^5 frames for uniform traffic and 100 simulations

with 10^4 frames for non-uniform. This difference is due to bottle necks in tree topology, RS

buffer work load grows exponentially with time. Mesh topology under perfect conditions

doesn’t increase delay or buffer work load in RSs or decreases service rate.

Table 5.1: Relay Zone performance measurements

Figure 5.1: Non uniform buffer work load with w=2

Uniform Traffic

Service Rate

[burst per

frame]

Average Hop Mean Buffer Work

load RS [bursts]

Tree 74.4543 3.5783 3.2091

Mesh 74.5125 3.5564 3.2869

Non- Uniform Traffic w=2

Tree 67.8956 3.5020 98.0449

Mesh 68.1804 3.4960 1.6844

30

With non uniform traffic bottle neck occurs in access link with resource allocation used in

uniform traffic above. With double resources in access link (4 Access Zone and [69, 11, 11,

23, 23, 23] Relay Zone) the mesh and tree topology performs better. Tree topology still has

bottle necks. Figure 5.1 shows a bottle neck at RS 22 and average work load over all RS of

98.004 approximately 58 times higher than the mesh topology with w=2. A median of 0.2467

bursts in buffer for tree topology and 0.1295 for mesh topology is shown in figure 5.1.

The mesh topology with an increase value of w decreases service rate in the topology about

6% with w=4. Figure 5.2 shows maximum service rate and mean RS buffer work load for each

value of w with different resource allocation scheme. The mean RS buffer work increases

100% with w=5. The appendix part C shows the performance results for different value of w

and resource allocations.

Figure 5.2: Mesh topology with non-uniform traffic distribution

31

2 2.5 3 3.5 4 4.5 5 5.5 60

10

20

30

40

50

60

AZ-burst per group

De

lay [fr

am

e]

2 2.5 3 3.5 4 4.5 5 5.5 635

40

45

50

55

60

65

70

75

AZ-bursts per group

Se

rvic

e R

ate

Ne

two

rk

2 2.5 3 3.5 4 4.5 5 5.5 60.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6x 10

9

AZ-bursts per group

Th

rou

gh

pu

t

5.2 Access Zone

MRC needs more resources in access zone therefore limiting service rate in the network.

Burst have higher throughput than in SD strategy. In figure 5.3 and table B in appendix it can

be seen that MRC gives best performance with Nmax=4 in access zone and [69 11 12 23 23

23] in Relay Zone. SD best performance is with Nmax=2 access zone and Nmax= [74 12 12 25

25 25] in relay zones. Short simulations duration (100 frames) are used because of rapid

bottle necks with some schemes like: MRC with Nmax=4 in access zone. Five thousand

simulations are run and average performance measurements calculated for every frame and

simulation.

Figure 5.3: Comparison between MRC and SD with different resource allocation schemes

The best resource allocation for SD and MRC was simulated with 1000 frames to see stability

and performance over a longer period. 5,000 simulations ran and mean performance

measurements were calculated. Table 5.3 shows the results from these simulations.

32

From table 5.2 we can see that there is a 3.5% increase in delay with MRC. With frames of

10ms gives on average a delay of 31.47ms without counting transmission delays in access

zone. The total throughput in MRC is 4.8% larger than with SD. With 10% less service rate

per frame than SD.

Table 5.2: Performance Measurements SD and MRC with 1000 frames

SD MRC

Resource allocation RZ 74 12 12 25 25 25/

AZ 2

RZ 67 11 11 22 22 22/

AZ 5

Delay per burst [frame] 3.1479 3.0446

Throughput per frame

[bps]

1.4481e+009 1.5181e+009

Service rate [burst per

frame]

73.9784 67.0124

Mean RS buffer work load

[burst]

5.0771 4.4364

33

6 Discussion:

6.1 Conclusion

Under stable conditions with uniform traffic the mesh topology performs the same as the

tree topology. On the other hand, mesh performance is better with non-uniform traffic.

Mesh topology is a more robust topology without sacrificing performance. Bursts have least

amount of probability of getting stuck in a bottle neck. Therefore less lost of burst in

network and re-transmission delay in non-uniform traffic environment.

MRC is good technique for achieving higher throughput per burst. There is a draw back in

service rate with a 10% decrease in the number of burst transmitted per frame. The total

throughput is increase 4.8% per frame. MRC increase throughput without sacrificing delay

constraints.

6.2 Future work

Some insight is gained by the simulations. Resource allocation to different zones is crucial in

performance of the network. Poor choice can degrade network performance greatly. Future

work for this thesis is to make an algorithm for different traffic model and burst types. How

can mesh topology with MRC resolve burst requirements? Certain burst like VOIP require

low delay of less than 160ms and real time streaming audio and video have low tolerance for

jittering.

34

7 References

[1] IEEE 802.16 Working group on Broadband Wireless Access, “Part 16: Air Interface for

Broadband Wireless access System, Amendment1: Multihop relay Specification”, June 2009, IBSN 978-

0-7381-5921-8 STD95915

[2] B. Timus, “Studies on the Viability of Cellular Multihop Networks with Fixed Relays”, Royal

Institute of Technology (KTH), May 2009, PhD Thesis, Kista, Sweden

[3] D. Ghosh, A. Gupta, P. Mohapatra, “Adaptive Scheduling of Prioritized Traffic in IEEE 802.16j

Wireless Networks”, Department of Computer Science, University of California, Davis, California, USA

[4] V. Genc, S. Murphy, J. Murphy, “Performance Analysis of transparent Relays in 802.16j MMR

Networks”, UCD School of computer science and Informatics, University College Dublin, Stillorgan,

Ireland

[5] M. Okuda, C. Zhu, D. Viorel, “Multihop Relay Extensions for WiMAX Networks- Overview and

Benefits of IEEE 802.16j Standard” , Fujitsu scientific and technical journal, ISSN 0016-2523 CODEN

FUSTA4 , vol. 44, no3, pp. 292-302 , January 2008, Japan

[6] E. Yeh; R. Berry, “Throughput optimal control of wireless networks with two-hop cooperative

relaying,” in Proc. IEEE Int. Symp Information Theory (ISIT), June 2007.

[7] D. Das; V. Sagar; R. K. Kalle; “Wi-MuMe: WiMAX MuLTIHOP MeSH – A Relay Based Approach

to Deliver Broadband to Rural Community”, International Conference on Communication

Convergence and Broadband Networking (ICCBN-08), July 17-20, 2008, Bangalore, India

[8] J. Shin, R. Kumar, Y. Shin, T. la Porta, “Multihop Wireless Relay Networks of Mesh Clients”,

Proceedings of IEEE WCNC, pp. 2717–2722, march 2008, Las Vegas, USA

[9] J. Sydir; R. Taori, “An Evolved Cellular System architecture incorporating relay stations” ,

Communications Magazine, IEEE, Volume 47, Issue 06, June 2009 Page(s):115– 121, Digital Object

Identifier 10.1109/MCOM.2009.5116808

[10] Y. Yang; H. Hu; J. Xu; G. Mao, “ Relay technologies for WiMAX and LTE-advanced mobile

systems”, Communications Magazine, IEEE, Volume 47, Issue 10, October 2009 Page(s):100 – 105,

Digital Object Identifier 10.1109/MCOM.2009.5273815

[11] WiMAX Forum, “Mobile WiMAX – Part I: A Technical Overview and Performance Evaluation”,

August 2006

[12] IEEE 802.16 Working group on Broadband Wireless Access, H. Zhang, P. Zhu, M. Fong, W.

Tong, D. Steer,G. Senarath, D. Yu, M. Naden, G.Q. Wang “MAC PDU Design for Supporting Data

Forwarding Schemes in 802.16j”, IEEE C802.16j-07/094, January 2007

35

[13] IEEE 802.16 task group, “Channel Models for Fixed Wireless Applications“, IEEE 802.16.3c-

01/29r4 edition, July 2001.

[14] IEEE 802.16j task group, “Multihop relay system evaluation methodology (channel model and

performance metric) “, IEEE 80216j-06_013r3, February 2007

[15] IST-4-027756, WINNER II, “D1.1.2 V1.1 WINNER II Channel Models, Part I Channel Models”,

February 2008, http://www.ist-winner.org/WINNER2-Deliverables/D1.1.2.zip.

[16] L. Ahlin, J. Zander, B. Silmane, “Principles of Wireless Communications”, Chapter 5

Diversity Systems, pages 360-367, Studentlitteratur, 2006, IBSN 91-44-03080-0

[14] IEEE 802.16j task group, “Harmonized definitions and terminology for 802.16j Mobile

Multihop Relay“, 80216j-06_014 edition, May 2006

36

8 Appendix:

A. M-files

Tree and Mesh Topology

for n=1:Nframes

for group =1:6

If

group=1

-Generate bursts at the MR-BS with

RSID

-Uniform/ Non-uniform traffic

Function [X, BS] =relay_zone(group,X BS,next_hop,ch_RS)

Find RS that Tx in group (RS_group)

For k=1: length (RS_group)

Find RS that tx (pac_pos)

l=1; Counter set to zero

While length (pac_pos)>0 && l<Nmax (group)

l=l+1;

Update Buffer size BS in old position (-1 burst),

Look up routing table

Update X, new position

Update X, hop count

Update BS new position (+1 burst)

pac_pos(1)=[]; packet sent eliminate from list

End

End

end

yes

no

Function [NHC, X, N_pack,BS]= acess_zone(X,k,BS)

Maximum burst tx in access zone 10= MaxN

Find RS that tx in access zone RS_AZ

Number of hop count empty (NHC),

Burst count empty (N_pack)

Burst Tx per RS RS_TX=0

For n=1: length (RS_AZ)

If RS_TX (m) <MaxN RS_TX update burst tx at RS (m) (+1 burst)

NHC = [NHC, hop count for tx burst in RS)];

N_pack tx add (+1 burst)

Burst tx store in vector RS_AZ_TX Update buffer size in RS (-1burst)

End

End

X (RS_AZ_TX, :) = []; burst eliminated from X

Performance measurements: mean_RS_BS= (mean_RS_BS+BS). /2; moving average of BS in

each RS

AHC=mean ([AHC, NHC]); new mean hop count

mean_pack_frame=mean ([mean_pack_frame, N_pack]);

Mean_BS=mean ([Mean_BS, BS']);

end

-Generate initial burst at MR-BS with RSID

-Uniform/ Non- Uniform

37

Mesh Topology with MRC

for n=1:Nframes

for group =1:6

If

group=1

-Generate bursts at the MR-BS with

RSID

-Uniform/ Non-uniform traffic

Function [X, BS] =mesh_relay_zone(group,X BS,next_hop,ch_RS,

num_hop)

Nmax=[74,12,12,25,25,25] Find RS that Tx in group (RS_group)

For k=1: length (RS_group)

Find RS that tx (pac_pos)

l=0; Counter set to zero

While length (pac_pos)>0 && l<Nmax (group)

l=l+1;

Update Buffer size BS in old position (-1 burst),

Look up routing table for RSID1 if not yet received,

else RSID2

Update X, new position

Update X, hop count

Update BS new position (+1 burst)

pac_pos(1)=[]; packet sent eliminate from list

End

End

end

yes

no

Function [NHC, X, N_pack,BS]= acess_zone(X,k,BS)

Maximum burst tx in access zone 2= MaxN

Find RS that tx in access zone RS_AZ

Number of hop count empty (NHC),

Burst count empty (N_pack)

Burst Tx per RS RS_TX=0

For n=1: length (RS_AZ)

If RS_TX (m) <MaxN RS_TX update burst tx at RS (m) (+1 burst)

NHC = [NHC, hop count for tx burst in RS)];

N_pack tx add (+1 burst)

Burst tx store in vector RS_AZ_TX Update buffer size in RS (-1burst)

End

End

X (RS_AZ_TX, :) = []; burst eliminated from X

Performance measurements: mean_RS_BS= (mean_RS_BS+BS). /2; moving average of BS in

each RS

AHC=mean ([AHC, NHC]); new mean hop count

mean_pack_frame=mean ([mean_pack_frame, N_pack]);

Mean_BS=mean ([Mean_BS, BS']);

end

-Generate initial burst at MR-BS with RSID1 and RSID2

-Uniform/ Non- Uniform

38

B. Routing tables

Tree Routing Table

Position of burst

RS

ID

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

1 1

2 20 2

3 20 3

4 21 4

5 21 5

6 22 6

7 22 7

8 20 23 2 8

9 20 25 3 9

10 20 25 3 10

11 21 26 4 1

1

12 21 27 4 12

13 21 28 5 13

14 21 28 5 14

15 22 29 6 15

16 22 30 6 16

17 22 31 7 17

18 22 31 7 18

19 20 2 19

20 20

21 21

22 22

23 20 23 2

24 20 24 2

25 20 25 3

26 21 26 4

27 21 27 4

28 21 28 5

29 22 29 6

30 22 30 6

31 22 31 7

32 20 23 32 2 8

33 20 25 33 3 9

34 20 25 3

4

3 10

35 20 25 3

5

3 10

36 21 26 3

6

4 1

1

37 21 27 37 4 12

38 21 28 3

8

5 13

39 21 28 39 5 14

40 21 28 40 5 14

41 22 29 41 6 15

42 22 30 42 6 16

43 22 31 43 7 17

44 22 31 44 7 18

45 22 31 45 7 18

39

The tree next node routing table is of size 46x31. This is because RS 32-46 don’t have child RS to relay

burst to. For example RS 3 has a burst with destination RSID=9. Position (3+1, 9) = the next hop will

be delivered a burst to RS25.

Mesh Routing Table

The next node table shows three possible neighboring RS for each RS. Each row shows RS in

first column and neighbor RS in the next. Note that not all RS have three neighboring RS.

46 20 24 46 2 19

RS Next Node

1 20 21 22 2 20 23 24 3 20 25 26 4 21 26 27

5 21 28 29 6 22 29 30 7 22 24 31 8 23 32 46

9 23 25 33 10 25 34 35

11 26 35 36 12 27 36 37

13 27 28 38 14 28 39 40

15 29 40 41

16 30 41 42 17 30 31 43

18 31 44 45 19 24 45 46

20 1 2 3 21 1 4 5

22 1 6 7 23 2 8 9

24 2 7 19 25 3 9 10

26 3 4 11 27 4 12 13

28 5 13 14 29 5 6 15

30 6 16 17 31 7 17 18

32 8 33 9

34 10 35 10 11

36 11 12 37 12 38 13 39 14 40 14 15 41 15 16 42 16 43 17 44 18 45 18 19 46 8 19

40

Each RS has at most 3 possible branches to relay burst. The num hop table shows the least hop count to a destination node RSID (columns) in a position RS (rows).

HOP COUNT TO DESTINATION RSID

PO

S

RS

1 2 3 4 5 6 7 8 9 1

0 11

1

2

1

3

1

4

1

5

1

6

1

7

1

8

1

9

2

0

2

1

2

2

2

3

2

4

2

5

2

6

2

7

2

8

2

9

3

0

3

1

3

2

3

3

3

4

3

5

3

6

3

7

3

8

3

9

4

0

4

1

4

2

4

3

4

4

4

5

4

6

0 2 2 4 8 8 4 4 4 4 4 6 6 8 8 8 6 6 4 1 5 5 3 3 3 3 5 7 7 7 5 5 5 5 5 5 7 7 9 9 9 9 7 7 5 5

0 8 4 2 2 4 8 8 6 6 4 4 4 4 4 6 6 8 8 5 1 5 7 7 4 3 3 3 3 5 7 9 7 7 5 5 5 5 5 5 5 7 7 9 9 9

1

0 4 8 8 4 2 2 6 6 8 8 8 6 6 4 4 4 4 4 5 5 1 7 3 7 7 7 5 3 3 3 7 7 9 9 9 9 7 7 5 5 5 5 5 5 5

2 0 2 4 4 4 4 6 4 4 4 6 6 6 6 6 6 6 6 1 3 3 5 5 3 3 5 5 5 5 5 7 5 5 5 5 7 7 7 7 7 7 7 7 7 7

5 0 4 6 8 8 6 2 2 4 6 8 8 1

0

1

0

1

0 8 6 4 5 7 7 1 5 3 5 7 9 5 9 7 3 3 5 5 7 9 9 11 11 11 11 9 7 5 3

2

4 0 6 6 6 4 2 4 6 8 8 8 8 8 6 6 4 4 2 5 5 3 5 1 7 7 7 7 9 5 3 5 7 9 9 9 9 9 9 7 7 7 5 5 3 3

2 2 0 4 4 4 4 4 4 6 6 6 6 6 6 6 6 6 4 1 3 3 3 3 5 5 5 5 5 5 5 5 5 7 7 7 7 7 7 7 7 7 7 7 5 5

6 4 0 6 8 8 6 4 2 2 4 6 8 1

0

1

0

1

0 8 8 6 5 7 7 3 5 1 5 7 11 9 9 7 5 3 3 3 5 7 9 11 11 11 11 9 9 7 5

3

4 6 0 2 4 6 6 8 6 4 2 4 4 6 6 8 8 8 8 5 3 5 7 7 5 1 3 5 5 7 7 9 7 5 3 3 5 5 7 7 7 9 9 9 9 9

2 4 4 0 2 4 4 6 6 6 6 6 4 4 4 6 6 6 6 3 1 3 5 5 5 5 5 3 3 5 5 7 7 7 7 7 7 5 5 5 5 7 7 7 7 7

4 4 2 0 6 6 6 6 4 4 2 4 6 8 8 8 8 8 6 3 5 5 5 5 3 1 5 7 7 7 7 7 5 5 3 3 5 7 9 9 9 9 9 9 7 7

4

6 8 6 0 4 6 8 1

0 8 6 4 2 2 4 6 8 8

1

0

1

0 7 5 7 9 9 7 5 1 3 5 7 9 11 9 7 5 3 3 3 5 5 7 9 9 11 11 11

2 4 4 2 0 4 4 6 6 6 4 4 4 6 6 6 6 6 6 3 1 3 5 5 5 3 3 5 5 5 5 7 7 7 5 5 5 5 7 7 7 7 7 7 7 7

6 8 6 4 0 6 8 1

0 8 8 6 8 2 2 4 6 8

1

0

1

0 7 5 9 9 9 7 5 3 1 5 7 9 11 9 9 7 5 5 3 3 3 5 7 9 11 11 11

5

4 6 6 6 0 2 4 8 8 8 8 4 6 4 2 4 4 6 6 5 5 3 7 5 7 7 7 5 1 3 5 9 9 9 9 9 9 9 5 3 3 5 5 7 7 7

2 4 4 4 4 0 2 6 6 6 6 6 6 6 8 6 4 4 4 3 3 1 5 3 5 5 5 5 5 5 3 7 7 7 7 7 7 7 7 7 7 7 5 5 5 5

4 6 6 4 2 0 6 8 8 8 6 6 4 4 2 4 6 8 8 5 3 5 7 7 7 5 5 3 1 5 7 9 9 9 7 7 7 5 5 3 3 5 7 9 9 9

6

6 6 8 8 6 0 4 8 8 1

0

1

0

1

0 8 6 4 2 2 4 6 7 7 5 7 5 9 9 9 7 5 1 3 9 9 11 11 11 11 9 7 5 3 3 3 5 5 7

2 4 4 4 4 2 0 6 6 6 6 6 6 6 4 4 6 6 8 3 3 1 5 5 5 5 5 5 3 3 5 7 7 7 7 7 7 7 7 5 5 5 5 7 7 7

4 2 4 6 6 6 0 4 4 6 6 8 8 1

0

1

0 8 4 4 2 3 5 5 3 1 5 5 7 7 9 7 5 5 5 7 7 7 9 9 11 11 9 9 7 5 3 3

7

6 6 8 8 6 4 0 6 8 1

0

1

0

1

0 8 8 6 4 2 2 4 7 7 5 7 5 9 9 9 7 5 3 1 7 9 11 11 11 11 9 9 7 5 5 3 3 3 5

4 2 4 6 6 6 4 0 2 4 6 8 8 8 8 8 6 6 4 3 5 5 1 3 3 5 7 7 7 7 5 3 5 5 7 9 9 11 9 9 9 7 7 5 5

0 1

8

6 4 6 8 8 6 4 0 6 8 8 1

0

1

0

1

0 8 8 6 4 2 5 7 5 5 3 7 7 9 9 7 7 5 7 9 9 9 11 11 11 9 9 9 7 5 3 1

4 2 4 6 6 6 4 2 0 6 6 8 8 8 8 8 6 6 4 3 5 5 1 3 5 5 7 7 7 7 5 3 7 7 7 9 9 9 9 9 9 7 7 4 3

4 4 2 4 6 6 6 6 0 2 4 6 6 8 8 8 8 8 6 3 5 5 5 5 1 3 5 7 7 7 7 7 3 3 5 7 7 9 9 9 9 9 9 7 7

9

0 1

4 4 2 4 6 6 6 4 2 0 4 6 6 8 8 8 8 8 6 3 5 5 3 5 1 3 5 7 7 7 7 5 3 5 5 7 7 9 9 9 9 9 9 7 5

0 1

10

6 6 4 4 6 8 8 8 6 0 2 4 6 8 8 1

0

1

0

1

0 8 5 5 7 7 7 5 3 5 7 7 9 9 9 7 1 3 5 7 9 9 9 11 11 11 9 9

4 4 2 2 4 6 6 6 4 4 0 4 4 6 6 8 8 8 6 3 3 5 5 5 3 1 3 5 5 7 7 7 5 5 5 5 5 5 7 7 7 9 9 9 7 7

6 6 4 6 8 8 8 6 4 2 0 8 8 1

0

1

0

1

0

1

0

1

0 8 5 7 7 5 7 3 5 7 9 9 9 9 7 5 3 1 5 9 9 11 11 11 11 11 11 9 7

11

6 9 6 4 6 8 8 1

0 8 8 0 2 4 6 8

1

0

1

0

1

0

1

0 7 5 7

1

0

1

0 7 5 3 5 7 9 9

1

0 9 9 5 1 3 5 7 7 9 11 11 11 11 11

4 6 4 2 4 6 6 8 6 6 4 0 2 4 6 8 8 8 8 5 3 5 7 7 5 3 1 3 5 7 7 9 7 7 5 5 3 5 5 7 9 9 9 9 9

6 6 4 4 6 8 8 8 6 4 2 0 6 8 8 1

0

1

0

1

0

1

0 5 5 7 7 7 5 3 5 7 7 9 9 9 7 5 3 1 7 9 9 9 11 11 11 9 9

12

0 1

4 6 4 2 4 6 6 8 6 6 4 2 0 6 6 8 8 8 8 5 3 5 7 7 5 3 1 5 5 7 7 9 7 7 5 5 2 7 7 7 9 9 9 9 9

4 6 6 4 2 4 6 8 8 8 6 6 0 2 4 6 6 8 8 5 3 5 7 7 7 5 5 1 3 5 7 9 9 9 7 7 7 3 5 5 7 7 9 9 9

13

0 1

4 6 6 4 4 4 6 8 8 8 6 4 2 0 4 6 6 8 8 5 3 5 7 7 7 5 3 1 3 5 7 9 9 9 7 5 5 3 5 5 5 7 7 9 9 9

0 1

14

6 8 8 6 4 4 6 1

0

1

0

1

0 8 8 6 0 2 4 6 8 8 7 5 5 9 7 9 7 7 5 3 5 7 11 11 11 9 9 9 7 9 1 3 5 7 9 9 9

41

4 6 6 4 2 2 4 8 8 8 6 6 4 4 0 4 4 6 6 5 3 3 7 5 7 5 5 3 1 3 5 9 9 9 9 7 7 5 5 5 5 5 7 7 7

6 8 8 6 4 6 8 1

2

1

0

1

0

1

0 6 4 2 0 8 8

1

0

1

0 7 5 7 9 9 9 7 5 3 5 7 9

1

3 11 11 9 9 9 5 3 1 9 9 9 11 11 11

15

6 8 8 8 6 4 6

1

0

1

0

1

0

1

0

1

0 8 8 0 2 4 6 8 7 7 7 9 7 9 9 9 7 5 3 5 11 11 11 11 11 11 9 9 1 3 5 7 7 9

4 6 6 6 4 2 4 8 8 8 8 8 6 6 4 0 2 4 6 5 5 3 7 5 7 7 7 5 3 1 3 9 9 9 9 9 9 7 7 5 5 3 5 5 7

6 8 8 6 4 4 6 1

0

1

0

1

0 8 8 6 4 2 0 6 8 8 7 5 5 9 7 9 7 7 5 3 5 7 11 11 11 9 9 9 7 5 3 1 7 9 9 9

16

0 1

4 6 6 6 4 2 4 8 8 8 8 8 6 6 4 2 0 6 6 5 5 3 7 5 7 7 7 5 3 1 5 9 9 9 9 9 9 7 7 5 3 3 7 7 7

4 4 6 6 6 4 2 6 6 8 8 8 8 8 6 6 0 2 4 5 5 3 5 3 7 7 7 7 5 5 1 7 7 9 9 9 9 9 9 7 7 7 3 3 5

17

0 1

4 4 6 6 6 4 2 6 6 8 8 8 8 8 6 4 2 0 4 5 5 3 5 3 7 7 7 7 5 3 1 7 7 9 9 9 9 9 9 7 5 5 3 5 5

0 1

18

6 4 6 8 8 6 4 4 6 8 8 1

0

1

0

1

0 8 8 6 0 2 5 7 5 5 3 7 9 9 9 7 7 5 5 7 9 9 9 11 11 11 9 9 9 7 1 3

4 2 4 6 6 4 2 4 4 6 6 8 8 8 6 6 4 4 0 3 5 3 3 1 5 5 7 7 5 5 3 5 5 7 7 7 9 9 9 7 7 7 5 5 5 5

6 6 8 8 8 6 4 8 8 1

0

1

0

1

0

1

0

1

0 8 6 4 2 0 7 7 5 7 5 9 9 9 9 7 5 3 9 9 11 11 11 11 11 11 9 7 7 5 3 1 9

19

6 4 6 8 8 8 6 2 4 6 8 1

0

1

0

1

0

1

0

1

0 8 8 0 5 7 7 3 5 9 9 9 9 7 5 3 3 5 7 7 9 11 11 11 11 11 11 9 9 9 1

1 5 5 3 3 3 3 7 7 7 5 5 5 5 5 5 5 5 5 0 2 2 6 4 6 4 4 4 4 4 4 8 8 8 8 6 6 6 6 6 6 6 6 6 6 6

5 1 5 7 7 5 3 3 3 5 7 9 9 9 7 7 5 5 3 0 6 4 2 2 4 6 8 8 6 6 4 4 4 6 6 8 1

0

1

0

1

0 8 8 8 6 6 4 4

20

5 5 1 3 5 7 7 5 3 3 3 5 5 7 7 9 9 9 6 0 4 6 4 6 2 2 4 6 6 8 8 6 4 4 4 4 4 4 8 8 8 1

0

1

0

1

0 8 8

1 3 3 5 5 3 3 5 5 5 5 7 7 7 5 5 5 5 5 2 0 2 4 4 4 4 6 6 4 4 4 6 6 6 6 6 8 8 8 6 6 6 6 6 6 6

5 5 3 1 5 7 7 7 5 5 3 3 3 5 7 9 9 9 7 4 0 6 6 6 4 2 2 4 6 8 8 8 8 6 4 4 4 4 6 6 8 1

0

1

0

1

0 8 8

21

5 7 7 5 1 3 5 9 9 9 7 5 3 3 3 5 5 7 7 6 0 4 8 6 8 6 4 2 2 4 6 1

0

1

0

1

0

1

0 8 6 4 4 4 4 6 6 8 8 8

1 3 3 3 3 5 5 5 5 5 5 5 5 5 5 7 7 7 5 2 2 0 4 4 4 4 4 4 4 6 6 6 6 6 6 6 6 6 6 6 6 8 8 8 6 6

5 7 7 5 3 1 5 9 9 9 5 5 5 5 3 3 3 5 7 6 4 0 8 6 8 6 6 4 2 2 4 1

0

1

0

1

0 8 8 8 8 6 4 4 4 4 6 6 8

21

5 3 5 7 7 5 1 5 5 7 7 9 9 9 7 5 3 3 3 4 8 0 4 2 6 6 8 8 6 4 2 6 6 8 8 8 1

0

1

0

1

0 8 6 6 4 4 4 4

3 1 3 5 5 5 3 5 5 5 5 7 7 7 7 7 5 5 3 2 4 4 0 2 4 4 6 6 6 6 4 6 8 6 6 6 8 8 8 8 8 8 6 6 4 4

5 5 7 5 7 7 7 1 7 9 9 11 11 11 9 9 7 5 3 6 8 6 0 4 8 8 1

0

1

0 8 8 6 2 8

1

0

1

0

1

0 12 12 12

1

0

1

0

1

0 8 6 4 2

22

7 5 3 9 9 7 5 5 1 3 5 7 7 9 9 9 9 9 7 4 6 6 0 9 9 7 4 6 8 8 8 8 2 4 4 6 8 8 1

0

1

0

1

0

1

0

1

0

1

0

1

0 8

3 1 3 5 5 5 5 3 3 5 5 7 7 7 7 7 7 6 5 2 4 4 1 0 4 4 6 6 6 6 6 4 4 6 6 8 8 8 8 8 8 8 8 8 8 8

3 5 5 5 5 3 1 7 7 7 7 7 7 7 5 5 3 3 5 4 4 2 6 0 6 6 6 6 4 4 2 8 8 8 8 8 8 8 8 6 6 6 4 4 4 6

23

7 5 7 9 9 7 5 3 5 7 9 11 11 11 9 7 5 3 1 8 6 8 4 0 8 8 1

0

1

0 8 6 4 4 6 8 8

1

0

1

0 12 12

1

0 8 8 6 4 2 2

3 3 1 3 5 5 5 5 5 5 3 5 5 7 7 7 7 7 5 2 4 4 4 4 0 2 4 6 6 6 6 6 4 4 6 6 8 8 8 8 8 8 6 6

5 3 5 7 7 7 5 3 1 7 7 9 9 9 9 9 7 7 5 4 6 6 2 4 0 6 8 8 8 8 6 4 2 8 8 1

0

1

0

1

0

1

0

1

0

1

0 8 8 6 4

24

7 7 5 5 7 9 9 9 9 1 3 5 7 9 9 11 11 11 11 6 6 8 8 8 0 4 6 8 8 1

0

1

0

1

0 2 2 4 6 8

1

0

1

0

1

0 12 12 12

1

0

1

0

3 3 1 5 5 5 5 5 3 3 5 7 7 7 7 7 7 7 5 2 4 4 4 4 2 0 8 6 6 6 6 6 4 4 4 8 8 8 8 8 8 8 8 8 6 6

3 5 5 1 3 5 5 7 7 7 5 3 3 5 5 7 7 7 7 4 2 4 6 6 6 0 2 4 4 6 6 8 8 8 8 4 4 4 6 6 6 8 8 8 8 8

25

7 7 5 5 7 9 9 7 5 3 1 3 5 7 9 11 11 11 11 6 6 8 8 8 4 0 4 6 8 1

0

1

0 8 6 4 2 2 4 6 8 8

1

0 12 12 12 12 8

3 5 5 1 3 5 5 7 5 5 3 7 5 5 5 7 7 7 7 4 2 4 6 6 4 2 0 4 4 6 6 8 6 6 4 4 6 6 6 8 8 8 8 8

7 7 5 5 7 9 9 9 7 5 3 1 9 11 11 11 11 11 9 6 6 8 8 8 6 4 0 8 8 1

0

1

0

1

0 8 6 4 2 2 12 12 12 12 12 12

1

0

1

0

26

5 7 7 5 3 5 7 9 9 9 9 9 1 3 5 7 7 9 9 6 4 6 8 8 8 6 0 2 4 6 8 1

0

1

0

1

0 8 8 2 4 4 6 8 8

1

0

1

0

1

0

3 5 5 3 1 3 5 7 7 7 5 5 5 5 3 5 5 7 7 4 2 4 6 6 6 6 4 0 2 4 6 8 8 8 8 6 6 4 6 6 6 8 8 8

5 7 7 3 5 7 7 9 7 7 5 3 1 9 9 9 9 9 9 6 4 6 8 8 6 4 2 0 6 8 8 1

0 8 8 8 6 4 2 8 8

1

0

1

0

1

0

1

0

1

0

27

7 9 9 7 5 5 7 11 11 11 11 11 11 1 3 5 7 9 9 8 8 6 1

0 8

1

0

1

0

1

0 0 4 6 8 12 12 12 12 12 12 2 2 4 6 8

1

0

1

0

1

0

3 5 5 3 1 5 5 7 7 5 7 5 3 3 5 9 9 7 7 4 2 4 6 6 6 4 4 2 0 8 8 8 8 8 8 6 6 4 4 4 1

0

1

0 8 8 8 8

3 5 5 5 5 1 3 7 7 7 7 7 7 9 5 3 3 5 5 4 4 2 6 4 6 6 6 6 0 2 4 8 8 8 8 8 8 8 1

0

1

0 4 4 4 6 6 6

28

7 9 9 9 9 5 7 11 11 11 9 7 5 3 1 3 5 7 9 8 1

0 8

1

0 8

1

0 8 6 4 0 4 6 12 12 12 12 8 8 6 4 2 2 4 6 8 8

1

0

3 5 5 5 5 1 3 7 7 7 7 7 5 5 3 5 5 5 5 4 4 2 6 4 6 6 6 4 2 0 4 8 8 8 8 8 8 6 6 4 4 6 6 6

7 9 9 5 5 7 11 11 11 9 9 7 7 7 3 1 11 11 8 8 1

0

1

0

1

0

1

0 8 6 8 6 4 0 12 12 12

1

0

1

0

1

0

1

0 8 8 4 2 2

1

0

1

0

1

0

29

5 5 7 7 7 5 3 7 7 11 9 9 9 9 9 11 1 3 5 6 6 4 6 4 8 8 8 8 8 0 2 8 8 1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0 2 4 4 6

3 3 5 5 5 3 1 5 5 7 7 7 7 7 5 5 5 5 3 4 4 2 4 2 6 6 6 6 4 4 0 6 6 8 8 8 8 8 8 6 6 6 4 4

5 7 7 7 5 3 5 9 9 9 9 9 9 7 5 3 1 11 9 6 6 4 8 8 8 8 8 8 4 2 0 1

0

1

0

1

0

1

0

1

0

1

0 8 8 6 4 4 2

1

0

1

0

30

7 5 7 9 9 9 5 5 7 9 9 11 11 11 11 11 11 1 3 6 8 6 6 4 8 8 1

0

1

0

1

0

1

0 0 6 8

1

0

1

0

1

0 12 12 12 12 12 12 2 2 4

3 1 3 3 5 5 5 3 1 5 5 7 7 7 7 7 5 5 5 5 3 4 4 2 4 2 6 6 6 6 4 4 0 6 6 8 8 8 8 8 8 6 6 6 4 4

42

5 7 7 7 5 3 5 9 9 9 9 9 9 7 5 3 1 11 9 6 6 4 8 8 8 8 8 8 4 2 0

1

0

1

0

1

0

1

0

1

0

1

0 8 8 6 4 4 2

1

0

1

0

7 5 7 9 9 9 5 5 7 9 9 11 11 11 11 11 11 1 3 6 8 6 6 4 8 8

1

0

1

0

1

0

1

0 0 6 8

1

0

1

0

1

0 12 12 12 12 12 12 2 2 4

1

32

1

33

1

34

5 5 3 5 7 7 7 5 3 1 5 7 7 9 9 9 9 9 7 4 6 6 4 6 2 4 6 8 8 8 8 6 4 2 0 8 8

1

0

1

0

1

0

1

0

1

0

1

0 8 6

5 5 3 3 5 7 7 7 5 5 1 3 5 7 7 9 9 9 9 4 4 6 6 6 4 2 4 6 6 8 8 8 6 0 2 4 6 8 8 8 8

1

0 8 8 8

35

5 5 3 3 5 7 7 7 5 3 1 5 7 7 7 9 9 9 7 4 4 6 6 6 4 2 4 6 6 8 8 8 6 6 2 0 6 8 8 8 8

1

0

1

0 8 8

5 7 5 3 5 7 7 9 7 7 5 1 3 5 7 9 9 9 9 6 4 6 8 8 6 4 2 4 6 8 8

1

0 8 8 8 0 2 4 6 6 8

1

0

1

0

1

0

1

0

1

0

36

1

37

1

38

1

39

5 7 7 5 5 5 7 9 9 9 7 5 3 1 5 7 7 9 9 6 4 6 8 8 8 6 4 2 4 6 8 10 10 10 8 8 6 4 2 0 8 8 8 10 10 10

5 7 7 5 13 3 5 9 9 9 9 7 5 5 1 3 5 7 7 6 4 4 8 6 8 6 6 4 2 4 6 10 10 10 10 8 8 6 6 0 2 4 6 8 8 8

40

5 7 7 5 3 3 5 9 9 9 7 7 5 3 1 5 5 7 7 6 4 4 8 6 8 6 6 4 2 4 6 10 10 10 8 8 8 6 4 2 0 6 8 8 8

5 7 7 7 5 3 5 9 9 9 9 9 7 7 5 1 3 5 7 6 6 4 8 6 8 8 8 6 4 2 4 10 10 10 10 10 10 8 8 8 0 2 4 6 6 8

41

1

42

1

43

1

44

5 5 5 7 7 5 3 7 7 9 9 9 9 9 7 5 5 1 5 6 4 4 6 3 8 8 8 8 6 4 2 8 8 10 10 10 10 10 10 8 6 6 4 2 0 8

5 3 7 7 7 5 3 3 5 7 7 9 9 9 9 7 3 5 1 4 6 4 4 3 6 6 8 8 6 6 4 4 6 8 8 8 10 10 10 8 8 8 6 0 2

45

5 3 5 7 7 7 5 1 3 5 7 9 9 9 9 9 7 7 5 4 6 6 2 4 4 6 8 8 8 8 6 2 4 6 6 8 10 10 10 10 10 10 8 8 8 0

5 3 5 7 7 5 3 5 5 7 7 9 9 9 7 7 5 3 1 4 6 4 4 2 6 6 8 8 6 6 4 6 8 8 8 10 10 10 8 8 8 6 4 2 0

46

43

C. Results

Relay Zone

Figure A: Work load for a uniform traffic for both mesh and tree topology using 10^5 frames.

Mesh Topology with 4 AZ and 69 11 11 23 23 23 RZ and Non-Uniform traffic

Average RS Buffer work

load

Mean Hop Count Service rate Median Buffer

work Load

W=2 1.8956 3.5009 68.6088 0.2216

W=3 2.3474 3.4593 66.2272 0.7017

W=4 349.8459 5.9744 67.6772 327.6099

Mesh Topology with 5 AZ and 66 11 12 22 22 22 RZ and Non-Uniform traffic

W=4 2.5024 3.4078 67.8901 0.8517

W=5 4.9556 3.3841 68.9395 0.7943

W=6 20.5787 4.9046 67.3455 3.4186

Table A: Performance Measurements for different value of W. Using 10^4 frames with

different resource allocation schemes.

Tree Topology Mesh Topology

Average buffer Work Load for each RSs and MR-BS using:

Arrival rate: 74 bursts/ frame

Frame allocation: 2Access Zone, 74 12 12 25 25 25 Relay Zone

Traffic distribution: uniform

44

5 10 15 20 25 30 35 40 450

5

10

15

20

25

30

MR-BS and RS

Mean R

S b

uffer W

ork

Load

Mean RS Buffer Work Load for SD and MRC

SD

MRC

Access Zone:

Table B: Comparison between MRC and SD with different resource allocation schemes

Figure B: Mean Buffer Work Load for SD and MRC in a mesh topology with best allocation

scheme and using 10^4 frames

SD

AZ-burst per group 2 3 4 5 6

RZ resource allocation

per group

74 12 12

25 25 25

72 11 12

24 24 24

69 11 12

23 23 23

67 11 11

22 22 22

64 11 11

21 21 21

Delay per burst [frame] 3.1490 2.3200 2.2406 2.2391 2.2372

Throughput per frame

[bps]

1.4502.e

+009

1.4104e

+009

1.3489e

+009

1.3107e

+009

1.2498e

+009

Service rate [burst per

frame]

74.0452 72.0232 68.9222 66.9323 63.8285

Mean RS buffer work

load [bursts]

5.0786 3.6422 3.3648 3.2655 3.1151

MRC

AZ-burst per group 2 3 4 5 6

RZ resource allocation

per group

74 12 12

25 25 25

72 11 12

24 24 24

69 11 12

23 23 23

67 11 11

22 22 22

64 11 11

21 21 21

Delay per burst [frame] 50.1738 23.8608 6.1718 2.9904 2.8092

Throughput per frame 8.3767e

+008

1.2625e

+009

1.5212e

+009

1.5160e

+009

1.4505e

+009

Service rate [burst per

frame]

37.6356 56.6410 68.9263 67.8682 64.8077

Mean RS buffer work

load [bursts]

82.5401 39.4448 9.4824 4.3639 3.9152