halim yanikomeroglu halim@scerleton scerleton/faculty/yanikomeroglu.html

IEEE ICC 2006 – H. Yanikomeroglu of 130

IEEE ICC 2006 – Tutorial 1011 June 2006, Istanbul, Turkey

Infrastructure-BasedInfrastructure-Based

Wireless Multihop, Relay, Mesh NetworksWireless Multihop, Relay, Mesh Networks

Broadband Communications & Wireless Systems (BCWS) Centre

Department of Systems & Computer Engineering

Carleton University

Ottawa

Halim Yanikomeroglu

[email protected]

www.sce.carleton.ca/faculty/yanikomeroglu.html



Destination

DD

Source

SS

Relay

Relaying: New Perspective vs Old Perspective

Conventional relaying: for coverage

Analog/digital dump (non-selective) repeaters

Satellite, microwave, cellular, deep space, …

RR

RR

RR

DD

S/RS/R

SS

RR

SS

Relay/mesh/multihop networks: for coverage, throughput, QoS, …, through cooperation

RR RR

RR



Relaying…

Relaying: paradigm shift in systems level

wired AWGN wireless fading wireless mesh

Impact in all layers of wireless communications

* propagation

* physical layer (PHY+IT+DSP) [channel capacity, cooperative relaying,…]

* multiple access layer (MAC) [RRM, scheduling, CAC, …]

* networking layer [load balacing, routing, handoff, …]

* higher layers and protocols

single-hop

multihop



Relaying…

Relaying: great interest in academia and industry* great interest does not necessarily mean successful realization* new network architecture network problem

physical layer: just one elementMAC, networking, protocols: important

* time to realization:TX diversity (Alamouti), turbo codes: 4-5 yearCDMA: 15 yearsad hoc networks: ∞relaying: will take some time, but will become a reality

single-hop

multihop



Relaying: Comprehensive Investigation Required

Simple example:

Relaying: links (hops) with less path-loss

higher spectral efficiency in each link

Relay: cannot receive and transmit at the same channel (half-dublex)

2-hop link 2 channels (time or frequency)

n-hop link 2 to n channels

Capacity gain or loss?



Infrastructure-based vs Infrastructure-less Multihop Networks

infrastructure-based multihop network

BS/AP common source or sink

infrastructure-less multihop network

systems & networking layers: many differences

physical layer: many similarities

cellular

WiFi

WiMax

(sensor)

ad hoc



OutlinePart I: Relaying for cost-effective ubiquitous high data rate coverage Capacity limited vs coverage limited networks Relaying: promising solution for coverage limited networks

Part II: Possibilities Analog relaying vs digital relaying Fixed relaying vs terminal relaying Homogeneous relaying (single air interface) vs heterogeneous relaying (dual air

interface)

Part III: Further exploitation of the relay/multihop/mesh architecture Cooperative relaying Novel diversity schemes Intelligent routing and scheduling

Diversity- and AMC (Adaptive Modulation and Coding)-aware routing in infrastructure-based TDMA multihop networks

BS-relay coordination Dynamic frequency hopping in cellular relay networks



Expectations for 4G Wireless Networks

WWRF (World Wireless Research Forum) & mITF predictions: mobile: up to 100 Mbps stationary/nomadic: up to 1Gbps !!!

More bandwidth more rates: it does not scale necessarily!

High bandwidth & high carrier frequency Tremendous stress on link budget

But how?

More bandwidth is needed

around 3 or 5 GHz band (World Radio Conference, Nov 2007)

advanced antenna technologies (MIMO, smart) advanced signal processing (modulation, coding, equalization) advanced radio resource management techniques

necessary but not sufficient

A fundamental upgrade in the network architecture is needed



QoS Eb

R: Data Rate = Pr

Pt

Pathloss

Propagation Conditions

Cell Size

BW

PHY

Cell Capacity

Low Data Rate

I)

II)

High Data Rate

Cellular Design Fundamentals

R.Eb



available capacity / cell < capacity demand

capacity limited

Capacity-Limited Networks

Solution: cell splitting



available capacity / cell > capacity demand

coverage limited

Coverage-Limited Networks

Solution: range extension



Capacity-Limited vs Coverage-Limited Networks

1G

2G

(3G)

4G

Capacity limited network grows as needed

great success

Ubiquitous high data rate coverage limited

very high deployment cost from the beginning

great challenge

WLAN: low deployment cost great success



R32

Coverage Extension through Digital Fixed Relays

Same high data rate coverage

• Low cost digital fixed relays located at strategic locations

No wired internet connection at relays

• Different from conventional fixed relays (selective relaying)

• Different from ad hoc networks (routing is less of an issue)

relay

relayrelay

relay

relayrelay

BS/AP BS/AP

What is a relay?



Coverage CDFs

propagation exponent = 3

0 5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

dB

Prob

[SIN

R >=

abs

ciss

a]

w/o relay (1000m)w/o relay (2000m)w/o relay (4000m)w/o relay (8000m)w relay (1000m)w relay (2000m)w relay (4000m)w relay (8000m)

0 5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

dB

Prob

[SIN

R >=

abs

ciss

a]

w/o relay (1000m)w/o relay (2000m)w/o relay (4000m)w/o relay (8000m)w relay (1000m)w relay (2000m)w relay (4000m)w relay (8000m)

propagation exponent = 3 propagation exponent = 3.5

H. Hu, H. Yanikomeroglu, D.D. Falconer, S. Periyalwar

“Range Extension w/o Capacity Penalty in Cellular

Networks with Fixed Relays”, Globecom 2004



propagation exponent = 3.5

Average spectral efficiency w.r.t. cell size Outage w.r.t. cell size

0 1000 2000 3000 4000 5000 6000 7000 80000

0.5

1

1.5

2

2.5

3

3.5

4

Cell size (m)

Aver

age

spec

tral e

ffici

ency

per

use

r (in

fo b

its/s

ec/H

z)

w/o relaywith relay

0 1000 2000 3000 4000 5000 6000 7000 80000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Cell size (m)

Out

age

w/o relayw relay



Cost-Efficient Range Extension

Same “average spectral efficiency” and “outage” w.r.t. cell size trends are observed for different values of Propagation exponent Cluster size Shadowing standard deviation BS transmit power

Ex: Range extension = x2 Cost [micro-BS] / Cost [relay] = 10

Cost [microcellular network] / Cost [relay network]

= Cost [L micro-BSs] / (Cost [L/4 micro-BSs] + Cost [6L/4 relays])

= 40/16 = 2.5

Relay networks: significant potential for range extension



62

x

xyzCost [conventional network] / Cost [relay network]:

(IEEE Globecom 2004)



Base station Antenna

Distributed Antennas

Antenna Remoting / Radio-on-Fiber

Infostations

Other Cost Effective Network Architecture Alternatives

non-ubiquitous coveragewiring cost wiring cost

Microcellular Network

Chinese FuTURE Project(Future Technology for Universal Radio Environment)

www.chinab3g.org/english/futureproject.htm



Ο :

• :

Central Node (CN)

Relay

: Wireless Link

•Only CN is connected to the backhaul

•No Tx & Rx on the same channel for a relay

•Nodes have two kinds of antenna

•Direct link with only the neighbor nodes

•Same BW for each primary link

Capacity of Cellular Fixed Relay/Mesh Networks

M: # of root nodes (trees)

N: # of nodes per tree

MN+1: # of nodes per cell



W (Hz)B (Hz)RCCN (bits/sec)RCFRN (bits/sec)RB

MN

: Total available bandwidth for a cell

RCCN = RW : Capacity of CCN is a function of W

RCFRN = (M.N+1)RB ≈ M.N.RB

: Capacity of the Conventional Cellular Network (CCN): Capacity of the Cellular Fixed Relay Network (CFRN): Capacity of a relay: Number of the root nodes: Number of nodes of a tree

B

W

: Available bandwidth for a relay



• • •



• • •

N



• • •

N

2

1N



• • •

2

1N

N

4

3N



Total Number Channel Groups: 12

1/

NNBW

12

1 B

NNW

12

1 BW R

NNR



WCFRN RMN

N

NR .

12

1

) .(1

) .(1 CCNWCFRN RM

p

pRM

p

pR

Previously it is stated that:

Then,

In general, if each node has child nodes:

BCFRN RNMR . .

WCFRN RMR . 3

2

p



q

k

q

kk

k

k

q

kk

k

T pp

p

pNN

p

p

pN

NN2 2

1

1

12

1

1

11

111

1

1

Total number channel groups when all the hop links use orthogonal channel groups:

Then:

WWq

k

q

kk

k

k

NCFRN MR

p

pMR

ppp

pNN

NR

1

11

11lim

2 21

1

1



When every other ‘hop’ links reuse the same channel groups:

When all of the links use orthogonal channel groups:

) .(1)1(log

1CCN

pCFRN RM

NR

Capacity Comparisons

) .(1 CCNCFRN RM

p

pR



Bandwidth Allocation to Access and Feeder Systems

Access system

cluster size N = 3Base Station service area

Relay service area

BT: Total BW

BA: total Access BW

BF: total Feeder BW

Ba: access BW for each relay

Bf: feeder BW for each relay

a: spectral efficiency for access

f: spectral efficiency for feeder

nr: number of relays

BT = BA+ BF

BA = NBa

BF = nr Bf

Bf f = Ba a

Each color represents a

frequency group

Florea, Yanikomeroglu

IEEE WCNC’06




a

f

r

T

F

nNB

B

1

1

access, feeder throughput

N = 3 19%, 81% 3.2 BT

N = 1 7%, 93% 3.7 BT

Bandwidth allocation for Bandwidth allocation for ACCESSACCESS

Bandwidth allocation for Bandwidth allocation for FEEDERFEEDER

f

arT

A

NnB

B

1

1

feeder portionaccess portion

Ex: nr = 25, f = 4, a= 2

if nr ∞, then BA/BT 0 and BF /BT 1

far

Taar

nN

BBnT

1

Throughput:

if nr ∞, then T f BT




100 Mbps – only in this small area

67 Mbps – in a much larger area

Why to use relays?



Relay Network Microcellular Network

Cost-effective high data rate coverage excellent moderate

Capacity (aggregate throughput) moderate excellent

Relay Network vs Microcellular Network

Rule of Thumb in Design:

* Deploy as many BSs/APs as needed according to capacity demand

* Then distribute the capacity in the coverage region evenly using as many relays as needed

Potential capacity: remains more or less the same

Usable capacity: increases (outage decreases) due to better coverage

Relays distribute the total capacity throughout the coverage region



b : spectral efficiency of single-hop link

ai : spectral efficiency in hop i

ac: net (overall) spectral efficiency of n-hop link

M: message size

B: bandwidth

T: message transfer time

Spectral Efficiency of n-hop Link with Orthogonal Channels

TMH = T1 + T2 + … + Tn (assuming orthogonal channels)

TMH = M/(Ba1)+ M/(Ba2)+ … + M/(Ban) = M/(Bac )

n

c

aaaa

a1

...1111

321



Multiplexing Loss in Multihop Relaying with Orthogonal Channels

When does it make sense to break a single-hop into multiple hops?

Low SNR case

Single-hop with 4 dB SNR ½-rate QPSK: 1 b/s/Hz

Two hops each with 12 dB SNR ¾-rate 16-QAM: 3 b/s/Hz

Net spectral efficiency: 1.5 b/s/Hz use multihop

High SNR case

Single-hop with 26 dB SNR full-rate 64-QAM: 6 b/s/Hz

Two hops each with 34 dB SNR 128-QAM: 7 b/s/Hz

Net spectral efficiency: 3.5 b/s/Hz use single-hop

Rule of thumb: low SNR multi-hop

high SNR single-hopopportunistic relaying



Multi-Hop Criterion

If single-hop SNR satisfies

then

[net spectral efficiency]n+1 >

[net spectral efficiency]n

n - number of hops p - path loss exponent

Assumptions:

- all links have same path loss exponent p

- All relays are placed uniformly on a in straight line from source to destination

SNR values under which there exists a SNR values under which there exists a ((n+1)n+1)-hop link -hop link withwith better spectral efficiency better spectral efficiency

compared with an compared with an nn-hop link-hop link

1

1

np

pn

n

n

-10

-5

0

5

10

15

20

2 2.4 2.8 3.2 3.6 4 4.4 4.8

Path Loss Exponent

SN

R [

dB]

1->2

2->3

3->4

One-hop region

Two-hop region

Three-hop region

Four(or more) -hop region

Florea, Yanikomeroglu

IEEE Globecom’05



Outline

Part II: Possibilities Analog relaying relaying vs digital relaying Fixed relaying vs terminal relaying Homogeneous relaying (single air interface) vs

heterogeneous relaying (dual air interface)



Analog Relaying vs Digital Relaying

Digital relaying (router, bridge)Regenerative relayingDecode-and-forward (detect-and-forward) relayingAdaptive (selective) decode-and-forward

Analog relayingNon-regenerative relayingAmplify-and-forward relaying On channel With frequency translation

Analog relaying noise propagationDigital relaying error propagation

Analog relaying may be better than digital relaying in certain scenariosHybrid analog/digital relaying: another possibility

digital relay

DF

CMPth



Fixed Relaying vs Terminal/Mobile Relaying

Terminal relaying: rich theoretical area, full of potentials

But, many technical challenges No service guarantee Increased energy consumption (fast battery draining) Increased transmit power (in CDMA) Additional hardware and functionality (higher terminal cost) Security issues Frequent hand-offs (especially in the presence of high mobility)

Terminal relaying: any incentives? Special applications: single team (law-enforcement, military, rescue) Non-battery powered fixed user terminals (802.16a) Cooperative relaying with simultaneous mutual benefits (symmetric cooperation) Personal area networks Commercial applications: business plan needed (air time offers?)

Ad hoc networks (infrastructureless): no internet connection!



Fixed Relaying vs Terminal/Mobile Relaying

Routing: easier in infrastructure-based multihop networks than infrastructureless ad hoc multihop networks Nodes with extra complexity and intelligence (BS/AP or fixed relays) Common source or destination

Routing with more demanding goals: possible

Expectations in 4G networks: first, fixed relays then, mobile/terminal relays

Single-hop (infrastructureless) ad hoc networks: possible

Multihop (infrastructureless) ad hoc networks: commercially difficult!



Heterogeneous (vs Homogeneous) Relaying

Decoupling of access and backbone networks Access: air interface A Backbone (feeder): air interface B

Customized air interfaces

Easier interference management

License-exempt bands can be utilized



Single-hop PC Two-hop PC

Single Air Interface vs Dual Air Interface

New issues emerge

Ex: power control in the reverse-link of two-hop CDMA networks

Walsh, Yanikomeroglu

IEEE CCECE’04



Outline

Part III: Further exploitation of the relay/multihop/mesh architecture Novel diversity schemes Advanced cooperative relaying Intelligent routing

Diversity- and AMC (Adaptive Modulation and Coding)-aware routing in infrastructure-based TDMA multihop networks

BS-Relay coordination Dynamic frequency hopping in cellular relay networks

WiMax mesh networks



Theoretical Literature on Relay/Mesh/Multihop NetworksVan der Meulen (68,71)El Gamal, Cover, Aref (79,80,82) [Stanford]Willems (83,85)

Sendonaris, Erkip (98-…) [Rice]Laneman [Notre Dame], Wornell [MIT] (00-…)

Gupta [ASU], Kumar [UIUC]Dohler [KCL]Nosratinia, Hunter [UTD]Tse [Berkeley]Hasna [Qatar], Alouini [Minnesota]Giannakis, Cai, Ribeiro [Minnesota]Host-Madsen [Hawaii]PottieZhang [ASU]Stefano [Brooklyn]Wittneben, RankovCho, Haas [Cornell]

Anghel, Emamian, Kaveh [Minnesota]Bolcskei, Nabar [ETH]Gastpar [Berkeley]Dawy [AUB]Kramer [Bell Labs]Franceschetti [UCSD]Herhold, Zimmermann [TUD]Vetterli [EPFL]Valenti Walke [Aachen]Karagiannidis [AU Thessaloniki]…

A few conference papers explosion in literature



Destination

DD

Source

SS

Relay

Relaying: New Perspective vs Old Perspective

coverage extension

RR

RR

RR

DD

S/RS/R

SS

RR

SS

RR RR

RR

Cooperative relaying virtual antenna array:

diversity, space-time coding, MIMO, …



Asymmetric vs Symmetric Cooperation

Asymmetric Cooperation: relay terminal between source and destination Only one terminal benefits Pathloss gain

Symmetric Cooperation: a pair of nearby terminals cooperate Immediate benefit for both terminals No pathloss gain



User Cooperative Diversity

)()()(

)()()(

)()()()(

21122

12211

02201100

tZtXKtY

tZtXKtY

tZtXKtXKtY

10K

20K

x

+x

+

x

x

+

E1

E2

21K

12K

0Y

1Y

2Y

2W

1W

2Z

1Z

0Z

1X

2X

Channel Model (full-duplex assumption)

Sendonaris, Erkip, Aazhang

IEEE T-COM, Nov. 2003

(ISIT 1998)



Implementation case example: CDMA Resources Distribution codes power allocation and

Using the same number of codes as in no cooperation scenario

No cooperation

),()( 1)1(

111 tcbatX

,)()(1 Period

2)1(

222 tcbatX

),(1)2(

11 tcba )(1)3(

11 tcba

,)(2 Period

2)2(

22 tcba 3 Period

2)3(

22 )(tcba

),()( 1)1(

1111 tcbatX

,)()(1 Period

2)1(

2212 tcbatX

),(1)2(

112 tcba )()( 2

)2(

2

^

141)2(

113 tcbatcba

,)(2 Period

2)2(

222 tcba

3 Period

2)2(

2241

)2(

1

^

23 )()( tcbatcba

Users transmit to BS

Users exchange

cooperative information

BS may hear

Constructed cooperative

signals are sent to BS

),(tci ia jia

With cooperation



N/2 N/2

T1 Tx T2: Tx T1: Tx

b) Orthogonal direct transmission

N

T1: Tx + T2: Tx

a) Direct, MAI transmission

N/4 N/4 N/4 N/4

T1 Tx + T2 Rx T2 Tx + T1 Rx T1 RelayT1: Tx + T2: Rx T1: Relay T2: Relay T2: Tx + T1: Rx

c) Orthogonal cooperative diversity (slow fading channel)

T4T2

T3T1

Engaging terminals in cooperation

Laneman, Tse, Wornell

IEEE T-IT, Dec’04

Laneman, Wornell

IEEE T-IT, Oct’03



Destination

DDSS

Source

Parallel Relays

rel

ay

rel

ay

rel

ay

first slot:

broadcast

second slot: multiple access

orthogonal multiplexing loss

beamforming CSI (overhead)

diversity order: up to R+1

provided that error propagation is prevented



Destination

DD

First Hop Second Hop

SS

Source

RlayRlay# R# R

RlayRlay# 1# 1

Adinoyi, Yanikomeroglu

WCNC’06 (IEEE TWireless’07)Multi-Antenna Aspects of Cooperative Fixed Relays

use few relays with multi-antennas

(even with selection combining)

instead of many relays with single antennas



Adinoyi, Yanikomeroglu

WWRF15, VTC’S06

Practical Cooperative Communication Schemes Through Fixed Relays

D

RelayProcessing

RelayProcessing

R1

R2

(a)

S2

S1

S1 (d1) ---> R1S2 (d2) ---> R2

R1 (d1) ---> D and R2

R2 (d2) ---> D and R1

R1(d2) ---> DR2 (d1) ---> D

(b)no need for incentives for cooperation

no security risk

no complexity incurred in terminals

complexity: moved to network




S1 (d1) ---> R1 , R2S2 (d2) ---> R1 , R2

R1 (d1(1)) ---> D

R2 (d2(2)) ---> D

R1(d2(1)) ---> D

R2 (d1(2)) ---> D

(b)

D

S1

S2

Multi-userdetection

SignalProcessinge.g., DSTC

Relay 1 (R1)

d1(1)

d2(1)

(a)

SignalProcessinge.g., DSTC

Multi-userdetection

Relay 2 (R2)

d1(2)

d2(2)



D

RelayProcessing

RelayProcessing

FRN1

FRN2

S1

S1 (d1) ---> FRN1, FRN2 S2(d2) ---> FRN1, FRN2

FRN1 (d1) ---> DFRN2 (d2) ---> D

FRN1(d2) ---> DFRN2 (d1) ---> D

S2

1

L

1

L




Multihop DiversityAnalysis of multihop channels with diversity Decoded relaying with diversity: intermediate terminals combine, digitally decode

and re-encode the received signal from all preceding terminals Amplified relaying with diversity: intermediate terminals combine and amplify the

received signal from all preceding terminals

Diversity in 2-Hop Links Mazen Hasna, Mohamed-Slim Alouini J. Laneman, Greg Wornell

Diversity in n-Hop Links (for fully connected networks) John Boyer, David D. Falconer, Halim Yanikomeroglu, “Multihop Diversity in

Wireless Relaying Channels,” IEEE Trans. on Communications, Oct. 2004

Main Observations Comparison of relaying and diversity schemes wrt BER Multihop Diversity > Multihop > Singlehop Amplified Relaying > Decoded Relaying DRMD improves when intermediate terminals are closer to the source terminal ARMD improves when intermediate terminals are closer to the destination

terminal



Full-Diversity Relays and Destination

Full diversity reception at all receivers

Requires n channels for n relaying hops

Complex relay behavior (diversity combining)

Source Relay1 Relay2 Relay3 Destination

Boyer, Falconer, Yanikomeroglu

IEEE T-COM, Oct. 2004



Aggregate SNR of Amplified Relaying Channels

John Boyer, David D. Falconer, Halim Yanikomeroglu, “On the Aggregate SNR of Amplified Relaying Channels”, IEEE Globecom 2004.

Aggregate Signal to Noise Ratio “Aggregate”: inclusion of propagated noise terms in the SNR formulation. Propagated noise terms are generated as amplified relaying terminals amplify

both the information and noise portions of received signals indiscriminately.

Motivated by findings indicating that the performance of amplified relaying can approach and in some cases exceed that of decoded relaying.

Aggregate SNR expressions developed for amplified relaying channels with given source, destination, and relaying terminals, link connectivity, link attenuation, transmit power, and receiver noise.

Aggregate SNR expression developed for following network connectivity: Serial Amplified Relaying Channels (serial node connectivity) Parallel Amplified Relaying Channels (parallel node connectivity) General Amplified Relaying Channels (general node connectivity)



Amplified Relaying

Source

terminal

Destination

terminal



ith Amplifying Relay

From

Terminal k:

ikkkkikik zar ,,, )(

ikz ,

iA

)( iiiis

1)(

:ionNormalizat

terminalfrompower trans.

terminalfrom noise propagated

terminalfrom symbol data

22

kk

k

k

k

E

k

k

k



Definitions

Aggregate SNR at for : Link SNR at for :

where is the transmitted power is the complex amplitude of the information symbol is propagated noise is distance-dependant attenuation, shadowing, and fading is the variance of the zero-mean Gaussian random variable

This model normalizes the transmit signal such that

iT iT)(iPk TT )(iPk TT

2

,,

2

2

,][ ikikkk

kkik

aNE

2

,,

,

ikik

kik

aN

ii

i

ikN , ikz ,

1][22 ii E

ika ,



Some Equations

Serial Amplified Relaying Channels (recursive form)

Serial Amplified Relaying Channels (sum of products form)

Parallel Amplified Relaying Channels

General Amplified Relaying Channels

)(11

),(1,

1),(

1,),( ,)( iPkkkPikkkPikiiP TT

1

,,

1),(

1),(

1),(

,

1),(

1),(

1),(),( ...)(

)()()(

lkj

iRlkj

kj

iRkjiRjTTT

TTTTllPkkPjjP

TTTTT

kkPjjPTT

jjPiiP

)(

,),(

iPk TTikiiP

)(

11),(

1,

1),(

1,),( )(

iPk TTkkPikkkPikiiP



Example Channels

s1

r2,3

s3

r3,4

s2

r1,2

T1

T2

T4

T3

s1

s3

r3,4

r2,4s2

r1,2

T1

T2

T4

T3r1,3

s1

r2,3

s3

r3,4

r2,4s2

r1,2

T1

T2

T4

T3

s1

r2,3

s3

r3,4

r2,4s2

r1,2

T1

T2

T4

T3r1,3

s1

r2,3

s3

r3,4

r2,4s2

r1,4

r1,2

T1

T2

T4

T3r1,3

Fig 1. Serial Connected Fig 2. Parallel Connected

(multi-route diversity)

Fig 4. General Connected 2

Fig 3. General Connected

Fig 5. Fully Connected



Aggregate SNR vs. Link SNR

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Fig. 5

T

1

T

2s

1

s

3

s

2T

1

T

4

s

1 s

3

s

2

T

2

T

4

T

3

s

1

s

3

s

2T

1

T

2

T

4

T

3

s

1 s

3

s

2T

1

T

2

T

4

T

3

s

1 s

3

s

2T

1

T

2

T

4

T

3

T

3



Comparison with a Linear Relation (high order multiplicative termsin formula at bottom of slide 62 removed)

T

1

T

2s

1

s

3

s

2T

1

T

4

s

1 s

3

s

2

T

2

T

4

T

3

s

1 s

3

s

2T

1

T

2

T

4

T

3

T

3

Fig. 1

Fig. 2

Fig. 5



Observations

Serial Amplified Relaying Channels: Allocate relatively more power to weaker links

Parallel Amplified Relaying Channels: Allocate relatively less power to weaker links

General Amplified Relaying Channels: Allocate relatively more power to weak links that are not parallel to strong links and relatively less power to weak links that are parallel to strong links

Maximizing Links in parallel (diversity gains) more important than maximizing links in serial (attenuation gains) for the example simulations.

For strong links in serial the performance is approximately linear with respect to the component link SNRs

For weak links in serial the performance is less than linear with respect to the component link SNRs

Amplified relaying may not be appropriate for very low SNR systems as propagated noise becomes limiting factor.



System Resource Constraints

John Boyer, David D. Falconer, and Halim Yanikomeroglu, ”Impact of System Resource Constraints on the Connectivity of Wireless Relaying Networks”, ICC 2005 (under review in TWireless)System resource constraints have a direct impact on the link connectivity of wireless relaying networks and therefore the possible distributed spatial diversity techniquesConstraints considered Number of Channels Available (NCA): N or 2 available channels Relay Combination (RC): Diversity combining or simple relay Destination Combination (DC): Diversity combining or simple relay Multiple Channel Reception (MCR): Multiple channels or single combined by

receiver Multiple Channel Transmission (MCT): Multiple channels or single transmitted

Possible constraint combinations are analyzed and reducedRelaying types Amplify-and-forward (analog) relaying Decode-and-forward (digital) relaying with error propagation Decode-and-forward (digital) relaying without error propagation



Full-Diversity Relays and Destination

Full diversity reception at all receivers

Requires n channels for n relaying hops



Boyer, Falconer, Yanikomeroglu

IEEE T-COM, Oct. 2004



2-Channel Diversity Relays and Destination

Successive transmitters along multihop path transmit/receive on alternating channels.

Requries 2 channels for n relaying hops.

Complex relay behavior (diversity combining).




2-Channel Diversity Relays w Full Diversity Destination

Alternating channels with full diversity at destination

Requires 2 channels for n relaying hops





Non-Diversity Relays w Full Diversity Destination

Alternating channels with full diversity at dest.

Requries 2 channels for n relaying hops.

Simple relay behavior (no combining).




System Connectivity Models

Models defined by the connectivity of source, relay, destination 1X: Terminal class X connected to one transmitter 2X: Terminal class X connected to the subset of transmitters on one channel FX: Terminal class X connected to all transmitters

Inter-model transitions based on minimum cost constraint sets:

FRFD

1R1D

1RFD

2RFDFS

2RFD

2R2DFS2R2D

1R2D2S1R2D

DC

MCT

MCR

RC

MCT

RC

MCR

MCT

RC MCR NCA

NCA

2R1D 2R1D2S

FR1D

RC DC

MCT

DC NCA

DC

S: Source

R: Relay

D: Destination



System Connectivity Models (Samples)

1R1D

1R2D

1RFD

2R2D

2RFD

FRFD

0

1

0

0

0

0

0

0

0

1

1

11

1

1

1 1

1

11

1

1

1

1

1

0

00 0

00

0

00

00

01

1

1 11

0 0 0

0

0

1

100



Minimum Cost Constraint Sets

Mark of ’X’ indicates that the constraint is lifted the capability described by the corresponding system resource is available

Model NCAN Channels

Available

RCRelay

Combination

DCDestination

Combination

MCRMultiple Channel

Reception

MCTMultiple Channel

Transmission

1R1D

1R2D X

1R2D2S X X

1RFD X X

2R1D X

2R1D2S X X

2R2D X X

2R2DFS X X X

2RFD X X X

2RFDFS X X X X

FR1D X X X

FRFD X X X X



Amplified Relaying

1R1D

1R2D

2R2D

1RFD

2RFD

FRFD

1R1D

2R2D

1RFD

2RFD

FRFD

FR1D

Singlehop



Decoded Relaying with Error Propagation

1R1D

2R2D2RFD

FRFD

1R2D1RFD

1R1D

FRFD

Singlehop



Decoded Relaying without Error Propagation

FRFD2RFD

1RFD

2R2D

1R2D

1R1DSinglehop

1R1D

2R2D

FRFD



Observation I

Simulation of connectivity models for amplified relaying, decoded relaying with error propagation, and decoded relaying without error propagation isolates the impact of each constraint

Impact summary of system resource constraints Relaying Method NCA RC DC MCR MCT Amplified Small Small Large Large Small Decoded w Prop Small Medium Medium Small Medium

Decoded w/o Prop Small Medium Large Large Small

Different impact for different relaying methods.

Connectivity priorities for optimal performance Amplified Maximize destination connectivity Decoded w Prop Equalize relay & destination connectivity Decoded w/o Prop Maximize destination connectivity & disjoint network paths



Observations II

Diversity order of the system is dependent on the connectivity Amplified relaying Dependent only on destination Decoded relaying w Prop Dependent only on minimally connected relay Decoded relaying w/o Prop Dependent on destination and disjoint paths

Guidance for the order in which the constraints should be lifted Amplified DC, MCR, RC, MCT Decoded w Prop RC, DC, MCT, MCR Decoded w/o Prop DC, MCR, RC, MCT

Impact of lifting NCA contraint when all other constraints are lifted is small Likely will not be implemented in practice since the cost of N orthogonal channels

per information signal transmission is very high with respect to spectral efficiency.



Ongoing WorkIncorporation of Interhop Interference Cancellation (IC) as a constraintExplicit separation of Common Channel Combination and Orthogonal Channel Combination as constraintsGeneralization of analysis for arbitrary number of channels available (K<N)Formalization of method for deriving system connectivity modelsMapping of models to cooperative diversity techniques in the literatureInterrelationships between system resource constriantsRelationship of system resource constraints to relay node placement

Grid placement Colinear equidistant between source and destination placement ’Bunched’ nodes placement between source and destination Random placement with varying uniformity of relay density

Practical issues and cost of system resource constraints Common channel combination techniques Cooperative coding Relay block size Spatial reuse of channels Wireless fading models Spectral efficiency



Coordination among BSs/APs and Relays

Coordination among BSs Scheduling Interference management Radio resource management Admission control …

Rich literature

Limited usage in practice in conventional cellular networks

May be used in cellular relay networks



Each terminal measures path losses to the neighboring bases and transmits this information to its serving base on a regular basis.

Each base communicates to several tiers of its neighbors the information about its own resource utilization (i.e. time slots, frequency hopping patterns and current power levels).

The serving base station calculates the interference level at each available resource, determines the least-interfered time slot and FH pattern pair, and assigns this to the terminal.

i. ii.

iii.

Base Station

Mobile terminal

CLASSICAL DYNAMIC FREQUENCY HOPPING WITH NETWORK ASSISTED RESOURCE ALLOCATION (DFH with NARA) – [AT&T Bell Labs]



MOBILE STATION 1

Measure Pathloss on BCCH for BS 1

Local Copy of FH Patterns For All BS

WIRELESS MEDIUM

Average

Send to BS1

Read and Use Specified FH Pattern

Measure Pathloss on BCCH for BS K

Average

Send to BS1….

Local Copy of Measurements For All MS from All BS

BASE STATION 1

To Other MobilesFrom Other

Mobiles

Manage Frequency Hop Patterns For This BS

Send Orders To MSs with Next FH Patterns

Collect Measurements From All MS in this BS Coverage Area

From Other Base Stations

To Other Base Stations To Other Base

Stations

From Other Base Stations

LANDLINE NETWORK

BLOCK DIAGRAM OF A CELLULAR SYSTEM THAT SUPPORTS DFH WITH NARA FOR DOWNLINK

….

….



Base Station

Relay Station

User Equipment

Cell Border

Relay or Base Neighborhood

Inter-relay and Relay-Base Communication

SYSTEM ARCHITECTURE FOR TWO-HOP COMMUNICATIONS



R1

R2

R3

R4

R6

R5

BS

R1: 3 in-cell interferers (R2,R6,BS) and 3 out-of-cell interferers (R3,R4,R5)

UE pathloss info: R1BS

BS already has resource utilization information of the in-cell interferers of R1

BS: decide on DFH pattern based on limited info

BSR1: DFH pattern

DFH with LIMITED INFORMATION (Time Slot 2)

Mubarek, Yanikomeroglu, Periyalwar



First Tier Interferers

Second Tier Interferers

Base Station

Relay Station

User Equipment

Cell Border

Relay or Base Neighborhood

INTERFERING SUB-CELLS

FIGURE 9



UE

Measure Pathloss for BS

Average out Rayleigh

Get the new FH Pattern

Measure Pathloss for Interfering Relay1


UEs IN RS NEIGHBORHOODS

IN-CELL RELAYS

Measure Pathloss for Interfering Relay2


Collect Pathloss Reports from UEs in RS Neighborhood

Notify RSs with the new FH Patterns for UEs in

RS Neighborhoods

Create new Random FH Patterns for UEs in RS

Neighborhoods from the pool of available and unblocked Resources

Store FH Patterns of all

UEs and RSs in Memory

BASE STATION

Calculate which resources result in a SIR less than the threshold SIR, SIRTh,

and block them

OTHER BASE STATIONS

OUT-OF-CELL RELAYS

LANDLINE NETWORK

NO COORDINATION

Get the new FH Pattern

Notify UEs in RS Neighborhoods with their

new FH Patterns

UE in RS-Neighborhoods



UE in BS service region: DFH with full information

DFH with LIMITED INFORMATION (Time Slot 2)



UE

Measure Pathloss for RS1 …


Get the new FH Pattern…

Measure Pathloss for RS6


UEs IN BS NEIGHBORHOOD Collect Pathloss Reports

from UEs in BS Neighborhood

Notify UEs in BS Neighborhood with their

new FH Patterns

Create new FH Patterns for UEs in BS Neighborhood

Store FH Patterns of all

UEs and RSs in Memory

BASE STATION

OTHER BASE STATIONS

OUT-OF-CELL RELAYS

LANDLINE NETWORK

IN-CELL RELAYS

NO COORDINATION

BS-Neighborhood, BS relays as interferers



Cooperative Induced Multi-user Diversity Relaying (CIMDR)

First hop Multi-user diversity exploits through transmission with maximum bit-rate

Second-hop Multi-user diversity exploits through transmission on a “good channel”

Two phase protocol: Feeding and delivery phase

Base Station

Relay

Destination user

Relay

Relay

Relay

Multi-user diversity

Transmission with maximum bit-rate

Navaie, Yanikomeroglu

VTC’S06



Node

Base Station (BS)

Node-BS Link

x

x

x

x

Node at the edge of the cell with high Path loss

Poor link due to strong Shadowing

Performance Improvements through the Mesh Architecture in TDMA based Broadband Fixed Cellular Network

Syed, Ahmed, Yanikomeroglu, Mahmoud

WCNC’04



Cellular Mesh Network with Global Resource Allocation

Nodes

Base Station (BS)

Node-BS Link

Node-Node Link



Algorithm for Constructing Routing Table

Step 1

Reject all node-node & node-BS links with PL>PLmaxStep 2

List all 2-hop & 3-hop routes between source node and BS(s)Step 3

Arrange in ascending order,the routes found in Step 2 using criterion

min{ max (PLi )} where i=1,2 or i=1,2,3

Step 4

If tie in max(PLi), then min{ PLi } route on the top

PL1 PL2 PL3



Route SelectionPolicyMinimum Number of Hops Route First

ConditionsFree slot(s) available on all hops

SINRrSINRth on the free slot(s)

Salient Features Less spectral resources used (time slots) Viable SINR links used (SINRrSINRth) Simple call admission policy Simple algorithm



Adaptive Modulation & Coding

SINR (dB) Code & Mod. Info. bps/hz

<4.65 - 0

4.65-7.45 ½ QPSK 1

7.45-10.93 ¾ QPSK 1.5

10.93-12.0 ½ 16-QAM 2.0

12.0-14.02 2/3 16-QAM 2.67

14.02-15.0 ¾ 16-QAM 3

15.0-17.7 7/8 16-QAM 3.5

17.70-19.0 2/3 64-QAM 4

19.0-21.94 ¾ 16-QAM 4.5

21.94-26.0 7/8 64-QAM 5.25

>26.0 64-QAM 6



Main Simulation Parameters

System Parameter Simulation Value

Network Cellular, Noise limited, 200 Nodes,

4-Square Cells, Cell Size = 3x3 km2

Multiple Access TDMA / FDD, 10 slots/channel

Propagation Channel nn-BS= 3.8, nn-n= 4, n-BS= 6dB, n-n= 4dB

Carriers & Bandwidth Single Carrier @ 2.5GHz, BW= 5 MHzs

No. of Channels = 2 to 6

Antenna Type 30o, switched beam, Gml= 7 dB, Gsl,bl= 0 dB, Rooftop (node end)

Transmit Power Fixed, Pt= 2 watts

Noise AWGN, Noise Power = - 130 dBW



Simulation Parameters … Cont.

System Parameter Simulation Value

Network Traffic Traffic Arrival : Poisson, =400-8000 burst/sec

Burst size : Exponential, =15 kbits

PLmax for Routing 126 dB

SINRth 4.65 dB

Frame specification Tf=10ms, 10 slots/frame

Slot allocated per hop 1

Upper limit on consecutive frame drop before retransmission

3



Simulation Assumptions

Snap shot processing at frame level All transmissions are slot synchronized Independent & fixed shadowing on all links Doppler shift negligible Multipath fading handled by micro diversity Infinite buffer size on the node All user nodes are active Separate control channels are available Continuous ARQ Protocol



Outage Probability



Outage Analysis of SH & MH Network, 2-Channels



Connectivity Analysis: MH Network, 2-Channels



Net Node Throughput



Diversity- and AMC (Adaptive Modulation and Coding)-Aware Routing inInfrastructure-based TDMA Multihop Networks

Hop0 to 4

Hop0 to 1

Hop1 to 2

Hop2 to 3

Hop0 to 5

Hop5 to 6

Connection to 3Connection to 4 Connection to 6

0AP

1

2

3

4

56

Extra channels are not used. Connections and hops are orthogonal in the time domain.

Time Domain – MAC Frame

Hares, Yanikomeroglu, Hashem

VTC’F03 & Globecom’03



Routing

Routing objective Select relay nodes and hop modulation/coding (MC) to maximize throughput

Throughput = (Information Rate bits/sec)*(1 - Probability of error) Increase Info. Rate or decrease end-to-end error rate to increase throughput. How?

-100 -50 0 50 100

-100

-80

-60

-40

-20

0

20

40

60

80

100

SingleHop Routing

1

2

3

4

5

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7

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64

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-100

-80

-60

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-20

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MultiHop Routing

1

2

3

4

5

6

7

8

9

10

11

12 13

14

15

16

17

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64



Hop0

Frame Allocation for Relaying

•Adaptive modulation and coding (AMC)

•Different MC used on hops

•Amount of data entering and exiting relaying nodes are equal

QAM64 QAM64

Hop10 1 2

QAM4

Hop0 20

Hop0

Hop0

Hop1Hop0 Hop1

Hop0



Multihop Diversity

Time Domain

MRC DecoderSymbols CRC

OK?

YesBits

DecoderSymbols YesBits

Node 3 Receiver Operation Equivalent

No

QAM64 QAM16 QAM64

Hop1 Hop2Hop0

Hop2

Hop0

Hop1



No

Hop0

Hop1

CRC OK?

CRC OK?

CRC OK?

Node 2 Receiver Operation Equivalent

0 1 2 3Hop2Hop1Hop1Hop0Hop0



Adaptive Modulation & Coding Maximization (AMCM)

Originally, hop modes were selected to maximize data rates on hops.

AMCM adapts hop modes to maximize the connection throughput for systems using MRC diversity.

Performed after route has been selected.

Possible modes a hop can assume is limited to the set of modes used in the connection (i.e. QAM16, QAM64, QPSK1/2).

For each iteration, examine all possible modes for all hops.

Change a mode for a single hop that generates the maximum metric for the connection.

Use the new set of modes for the subsequent iteration.

Stop when a mode change does not increase the metric for the connection.

Hop1 Hop2 Hop3

QAM64QAM16 QPSK1/2

From all possible changes, changing the mode of hop 2 from QAM64 to QAM16 generates the

max. metric.

Stop when mode changes do not increase the connection metric.

Hop1 Hop3

Use the new set of modes to continue to maximize the metric.

QPSK1/2QAM16

Hop2

QAM16

Hop2

QAM64



Routing Types

Route Selection Strategies: Single Hop (SH) Multihop (MH) Multihop Selection Combining Diversity (MHSC)

Routing metric factors selection combining diversity Multihop MRC Diversity (MHMRC)

Routing metric factors MRC diversity Multihop Adaptive Modulation MRC Diversity (MHAMMRC)

Routing metric factors MRC diversity Uses AMCM

Hybrid Digital and Analog Relaying (HDAR) Nodes relay incorrectly decoded signals as analog signals



Routing – Example (1)

Iteration Next = 1Current = 0

AP A A

B B

C

D

E

C

D

E

Initially, routes only contain the AP and destination node.

Examine all next routes.

Next routes (black) built off current routes (red).

Next routes generating max. metrics are in purple.

If metric of next route > metric of current route, on next iteration, current route = next route.

Next iteration routes: B: AP-A-B C: AP-E-C E: AP-A-E





AP A

B

D

E

C

E

A

B

C

D

E

Only check routes to nodes not included in current route.

Next iteration routes: C: AP-A-E-C D: AP-E-C-D

Need to only examine next routes built from routes which changed on previous iteration.





AP A

B

E

C

E

C

D

A

B

D

Stop searching when next generation of routes do not yield higher metrics.

Final connections: A: AP-A B: AP-A-B C: AP-A-E-C D: AP-E-C-D E: AP-A-E



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SingleHop Routing

1

2

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Simulation - Routing Example



-100 -50 0 50 100

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-80

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MultiHop Routing

1

2

3

4

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Simulation - Routing Example



NLOS office environmentETSI-A channel model

Rayleigh fading 50ns RMS delay spreadNoise power, PN0 = -90dBmPropagation exponent, α = 3.4Carrier frequency, fc = 5.3GHzShadowing, σ = 5.1dBOmni-directional antennasFixed transmit power, Ptx = 23dBmAdaptive modulationConstant interferenceHexagonal radius, R = 128mCluster size, N = 12No mobility

Simulation - Parameters



Simulation – Throughput, 128m Cell

0 5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

T, [Mbps]

Pr(

Use

r T

hrou

ghpu

t <

= T

)

SHMHMHSCMHMRCMHAMMRCMHMRC-HDARMHAMMRC-HDAR



Simulation - Number of hops, 128m Cell

0 1 2 3 4 5 6 7 8 9 100

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Number of Hops, d

Pr(

Num

ber

of H

ops

in R

oute

= d

)MHMHSCMHMRCMHAMMRCMHMRC-HDARMHAMMRC-HDAR



Simulation – Throughput, 256m Cell

0 1 2 3 4 5 6 7 8 9 100

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

T, [Mbps]

Pr(

Use

r T

hrou

ghpu

t <

= T

)

SHMHMHSCMHMRCMHAMMRCMHMRC-HDARMHAMMRC-HDAR



Simulation - Number of hops, 256m Cell

0 1 2 3 4 5 6 7 8 9 100

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Number of Hops, d

Pr(

Num

ber

of H

ops

in R

oute

= d

)MHMHSCMHMRCMHAMMRCMHMRC-HDARMHAMMRC-HDAR



Simulation Results

Routing Type System Diversity

Avg. Network Throughput [Mbps] Avg. Hops in Route

128m Cell 256m Cell 128m Cell 256m Cell

SH None 7.75 2.07 1 1

MH None 12.77 4.17 2.21 2.93

MHSC SC 13.17 4.70 2.64 4.17

MHMRC MRC 13.19 4.70 2.62 4.14

MHAMMRC MRC 13.26 4.85 2.62 4.24

MHAMMRC-HDAR MRC 14.32 5.62 2.56 3.70

Routing Type – routing/metric typeSystem Diversity – form of diversity used at nodesSH = singlehop, MH = multihop (routing algorithm)MHAM = multihop adaptive modulation (routing algorithm)



Observations

Multihop routes Optimal 2-hop routesDiversity techniques: very attractive -- they do not use additional radio resources (power or bandwidth)Routing: incorporates diversity benefitsHDAR: increases diversity benefitsAverage aggregate throughput: increases 2-3XOutage: reduces very significantly (range extension: remarkable)Strategically placed fixed relayers: may be very attractiveCan be used in any TDMA network, if PER models are known & channel updates supported

For more information: Shoaev Hares, Halim Yanikomeroglu, and Bassam Hashem,

"Diversity- and AMC (Adaptive Modulation and Coding)-Aware Routing in TDMA Multihop Networks", IEEE GLOBECOM 2003

Shoaev Hares, Halim Yanikomeroglu, and Bassam Hashem, "A relaying algorithm for multihop TDMA TDD networks using diversity", IEEE VTC Fall 2003



Previous Standardization Efforts

Opportunity-driven multiple access (ODMA) – 1999, 3GPP

HiperLAN/2 (non-contention based multiple access)



Current Interest in Relay/Mesh/Multihop Networks (1) IEEE 802.11s – WLAN (Wireless Local Area Network) ESS Mesh Networking

Auto-configuring multihop paths between APs in a wireless distribution system. Targeted to be approved by 2008.

IEEE 802.15.5 – WPAN (Wireless Personal Area Network) Mesh Networking Aims at determining the necessary mechanisms that must be present in the PHY and MAC layers of

WPANs to enable mesh networking. Targeted to be approved by 2007.

IEEE 802.16 – WMAN (Wireless Metropolitan Area Network) 802.16-2004 standard “Air Interface for Fixed Broadband Wireless Access Systems”: approved in July

2004. MAC layer supports an optional mesh topology. 802.16e amends 802.16 to support mobility for the devices operating in the 2-6 GHz licensed bands. An optional mesh mode is being considered based on 802.16e-2005 OFDMA

MMR-SG: Mobile Multihop Relay Study Group 802.16j (Taipei, Sep’05; Vancouver, Nov’05; New Delhi, Jan’06; Denver, Mar’06)http://grouper.ieee.org/groups/802/16/sg/mmr/http://ieee802.org/16/sg/mmr/

IEEE 802.20 – MBWA (Mobile Broadband Wireless Access) Aims at developing the specification of PHY and MAC layers of an air interface for interoperable mobile

broadband wireless access systems, operating in licensed bands below 3.5 GHz, optimized for IP-data transport, with peak data rates per user in excess of 1 Mbps.

Expected to support the mesh architecture. http://grouper.ieee.org/groups/802/11/index.html

http://www.802wirelessworld.com



Current Interest in Relay/Mesh/Multihop Networks (2)

Cellular 4G Networks (WINNER Project)

Propriety solutions by industry BelAir, Firetide, Strix, Tropos, RoamAD, Mesh Networks, … Nortel, Nokia, IBM, …

Booming literature



WINNER – Wireless World Initiative New RadioIntegrated Project funded by European Union under the 6th Framework Program (FP6)

Objective: “to develop a ubiquitous radio system concept based on global requirements for mobile communication systems beyond 3G. The project covers a full scope from short-range to wide-area scenarios and will provide significant improvement to current systems in terms of performance, efficiency, coverage and flexibility.”

01 Jan 2004 – 31 Dec 2009 (three 24-month phases)

~ 50 partners (all European, except 2 Chinese & 1 Canadian [Carleton]) Manufacturers, network operators, academic institutions and research centres Including Siemens, Alcatel, DoCoMo Europe, Ericsson, Nokia, France Telecom,

Fujitsu Europe, IBM Europe, Philips, Samsung Europe, Vodafone, Qualcom Europe, Nortel Europe

Relaying: integral part of WINNER network deployment conceptCheck https://www.ist-winner.org Public Deliverables D3.x



Concluding Remarks

Infrastructure-based multihop networks: cost-effective ubiquitous high data rate coverage in future wireless networks

Fixed relay stations with add-on terminal relays

Impact in all layers of wireless communications Propagation, PHY, MAC, networking, higher layers and protocols

Relay networks will soon become a realityGoal: to develop advanced cooperation protocols and algorithms among relays and APs to obtain further performance gains at physical layer (cooperative diversity, virtual antenna arrays, …) systems layer (interference avoidance and management) networking layer (smart scheduling and routing, load balancing, …)

by relying on other advanced technologies, such as OFDM(A) and MIMO, as much as possible.



Tutorial/Overview/Perspective Papers

H. Yanikomeroglu "Fixed and mobile relaying technologies for cellular networks", Second Workshop on Applications and Services in Wireless Networks (ASWN'02), pp. 75-81, 3-5 July 2002, Paris, France.

H. Yanikomeroglu, "Cellular multihop communications: infrastructure-based relay network architecture for 4G wireless systems", the 22nd Queen's Biennial Symposium on Communications (QBSC'04), 1-3 June 2004, Queen's University, Kingston, Ontario, Canada; invited paper.

R. Pabst, B. H. Walke, D. C. Schultz, P. Herhold, H. Yanikomeroglu, S. Mukherjee, H. Viswanathan, M. Lott, W. Zirwas, M. Dohler, H. Aghvami, D. D. Falconer, and G. P. Fettweis, “Relay-based deployment concepts for wireless and mobile broadband radio”, IEEE Communications Magazine, vol. 42, no. 9, pp. 80-89, September 2004.

R. Bruno, M. Conti, and E. Gregori, “Mesh networks: commodity multihop ad hoc networks”, IEEE Communications Magazine, vol. 43, vol. 3, pp. 123-131, March 2005.



Relay/multihop/mesh networks research at Carleton University

Halim Yanikomeroglu

2 PDF

7 Ph.D. students

2 M.A.Sc. students

6 B.Eng. students

visiting professors and researchers

[email protected]

www.sce.carleton.ca/faculty/yanikomeroglu.html

halim yanikomeroglu halim@scerleton scerleton/faculty/yanikomeroglu.html

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