utilizing beamforming antennas for wireless multi-hop networks
DESCRIPTION
Utilizing Beamforming Antennas for Wireless Multi-hop Networks. Romit Roy Choudhury Dept. of Computer Science University of Illinois at Urbana-Champaign. Wireless Multihop Networks. Collection of wireless hosts Relay packets on behalf of each other Together form an arbitrary topology - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/1.jpg)
1
Utilizing Beamforming Antennas for Wireless Multi-hop Networks
Romit Roy Choudhury
Dept. of Computer ScienceUniversity of Illinois at Urbana-Champaign
![Page 2: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/2.jpg)
2
Wireless Multihop Networks
B
Collection of wireless hosts Relay packets on behalf of each other Together form an arbitrary topology May be connected to wired infratructure
2 reasons to prefer multihop Capacity and Power constraint
A
C
D
![Page 3: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/3.jpg)
3
Applications
Multihop networks gained wide popularity Began with military applications
New applications proving to be commercial Already beginning to appear around us
For Example …
![Page 4: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/4.jpg)
4
Wireless Multihop Networks
RFID
RFID
Sensors
RFID Readers
![Page 5: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/5.jpg)
5
Wireless Multihop Networks
![Page 6: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/6.jpg)
6
Wireless Multihop Networks
![Page 7: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/7.jpg)
7
Wireless Multihop Networks
Internet
![Page 8: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/8.jpg)
8
Protocol Design
Numerous challenges Connectivity (nodes can be mobile) Capacity (increasing demand) Reliability (channels fluctuate) Security QoS …
Many protocols designed
One commonality among most protocols
![Page 9: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/9.jpg)
9
Omnidirectional Antennas
Internet
![Page 10: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/10.jpg)
10
CTS = Clear To Send
RTS = Request To Send
IEEE 802.11 with Omni Antenna
D
Y
S
M
K
RTS
CTS
X
![Page 11: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/11.jpg)
11
IEEE 802.11 with Omni Antenna
D
Y
S
X
M
Ksilenced
silenced
silenced
silencedData
ACK
![Page 12: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/12.jpg)
12
IEEE 802.11 with Omni Antenna
DS
X
M
Ksilenced
silenced
silenced
Y
silencedData
ACK
D
silenced
E
silencedA
silencedC
silenced
F
silenced
B
silenced
G
silenced
`` Interference management ``A crucial challenge for dense multihop networks
![Page 13: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/13.jpg)
13
Managing Interference
Several approaches Dividing network into different channels Power control Rate Control …
Our focus Exploiting antenna capabilities
•Switched Beam Antennas•Steerable Antennas•Reconfigurable Antennas, etc.
Many becoming commercially available
For example …
![Page 14: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/14.jpg)
14
Electronically Steerable Antenna [ATR Japan]
Higher frequency, Smaller size, Lower cost Capable of Omnidirectional mode and Directional
mode
![Page 15: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/15.jpg)
15
Switched and Array Antennas
On poletop or vehicles Antennas bigger No power constraint
![Page 16: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/16.jpg)
16
Antenna Abstraction
3 Possible antenna modes Omnidirectional mode Single Beam mode Multi-Beam mode
Higher Layer protocols select1. Antenna Mode2. Direction of Beam
![Page 17: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/17.jpg)
17
Antenna Beam
Energy radiated toward desired direction
A
Pictorial Model
A
Main Lobe (High gain)
Sidelobes (low gain)
![Page 18: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/18.jpg)
18
Directional Reception
Directional reception = Spatial filtering Interference along straight line joining
interferer and receiver
A BC
D
Signal
Interference
No Collision at A
A B
C
D
Signal
Interference
Collision at A
![Page 19: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/19.jpg)
19
Will attaching such antennas at the radio layer yield most of the benefits ?
Or
Is there need for higher layer protocol support ?
![Page 20: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/20.jpg)
20
We design a simple baseline MAC protocol(a directional version of 802.11)
We call this protocol DMAC and investigate its behavior through simulation
![Page 21: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/21.jpg)
21
Remain omni while idle Nodes cannot predict who will trasmit to it
DMAC Example
D
Y
S
X
![Page 22: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/22.jpg)
22
RTS
DMAC Example
D
Y
S
X
Assume S knows direction of D
![Page 23: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/23.jpg)
23
RTS
RTSCTS
DMAC Example
D
Y
S
X
DATA/ACK
X remembers not to initiate transmission toward D
![Page 24: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/24.jpg)
24
Intuitively
Performance benefits appear obvious
![Page 25: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/25.jpg)
25
However …
0
100
200
300
400
0 500 1000 1500 2000 2500
Sending Rate (Kbps)
Agg
rega
te T
hrou
ghpu
t (K
bps)
802.11
DMAC
Sending Rate (Kbps)
Th
rou
gh
pu
t (K
bp
s)
![Page 26: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/26.jpg)
26
Clearly, attaching sophisticated antenna hardware is not sufficient
Simulation traces revealed various new challenges
Motivates higher layer protocol design
![Page 27: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/27.jpg)
27
Research Contribution
Identified several new challenges
Designed MAC and Routing protocols MMAC, ToneDMAC, CaDMAC DDSR, CaRP Cross-Layer protocols – Anycasting Improved understanding of theoretical capacity
Developed prototype testbed
![Page 28: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/28.jpg)
28
Research Contribution
Identified several new challenges
Designed MAC and Routing protocols MMAC, ToneDMAC, CaDMAC DDSR, CaRP Cross-Layer protocols – Anycasting Improved understanding of theoretical capacity
Developed prototype testbed
![Page 29: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/29.jpg)
29
Self Interferencewith Directional MAC
New Challenges [Mobicom 02]
![Page 30: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/30.jpg)
30
Unutilized Range [Best Paper, PWC 03]
Longer range causes interference downstream Offsets benefits
Network layer needs to utilize the long range Or, MAC protocol needs to reduce transmit power
A B CData
D
route
![Page 31: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/31.jpg)
31
New Hidden Terminal Problemswith Directional MAC
New Challenges II …
![Page 32: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/32.jpg)
32
New Hidden Terminal Problem [IEEE TMC]
Due to gain asymmetry
Node A may not receive CTS from C i.e., A might be out of DO-range from C
B CAData
RTSCTS
![Page 33: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/33.jpg)
33
New Hidden Terminal Problem
Due to gain asymmetry
Node A later intends to transmit to node B A cannot carrier-sense B’s transmission to C
B CAData
Carrier Sense
RTSCTS
![Page 34: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/34.jpg)
34
New Hidden Terminal Problem
Due to gain asymmetry
Node A may initiate RTS meant for B A can interfere at C causing collision
B CADataRTS
Collision
![Page 35: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/35.jpg)
35
Deafnesswith Directional MAC
New Challenges III …
![Page 36: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/36.jpg)
36
Deafness [ICNP 04]
Node N initiates communication to S S does not respond as S is beamformed toward
D N cannot classify cause of failure Can be collision or deafness
S D
N
Data
RTS
M
![Page 37: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/37.jpg)
37
Channel Underutilized
Collision: N must attempt less often Deafness: N should attempt more often
Misclassification incurs penalty (similar to TCP)
S D
N
Data
RTS
M
Deafness not a problem with omnidirectional antennas
![Page 38: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/38.jpg)
38
Deafness and “Deadlock”
Directional sensing and backoff ... Causes S to always stay beamformed to D X keeps retransmitting to S without success Similarly Z to X a “deadlock”
DATA
RTS
X
DS
Z
RTS
![Page 39: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/39.jpg)
39
MAC-Layer CaptureThe bottleneck to spatial reuse
New Challenges IV …
![Page 40: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/40.jpg)
40
Typically, idle nodes remain in omni mode When signal arrives, nodes get engaged in
receiving the packet Received packet passed to MAC If packet not meant for that node, it is dropped
Capture [HotNets 03]
Wastage because the receiver could accomplish useful communication
instead of receiving the unproductive packet
![Page 41: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/41.jpg)
41
Capture Example
A B
C
D
Both B and D are omni whensignal arrives from A
A B
C
D
B and D beamform to receivearriving signal
![Page 42: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/42.jpg)
42
Research Contribution
Identified several new challenges
Designed MAC and Routing protocols MMAC, ToneDMAC, CaDMAC DDSR, CaRP Cross-Layer protocols – Anycasting Improved understanding of theoretical capacity
Developed prototype testbed
![Page 43: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/43.jpg)
43
Impact of Capture
Beamforming for transmission and reception only is not sufficient
Antenna control necessary during idle state also
A B
C
DA B
C
D
![Page 44: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/44.jpg)
44
Capture-Aware MAC (CaDMAC) D monitors all incident traffic Identifies unproductive traffic
Beams that receive onlyunproductive packets are turned off
However, turning beams offcan prevent useful communication in future
MAC Layer Solution
A B
C
D
![Page 45: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/45.jpg)
45
CaDMAC turns off beams periodically Time divided into cycles Each cycle consists of
1.Monitoring window + 2. Filtering window
1 2
CaDMAC Time Cycles
1 12 2
cycle
time
All beams remain ON,monitors unproductive beams
Node turns OFF unproductivebeams while it is idle.
Can avoid capture
![Page 46: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/46.jpg)
46
CaDMAC Communication
Transmission / Reception uses only necessary single beam
When node becomes idle, it switches back to appropriate beam pattern Depending upon current time window
![Page 47: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/47.jpg)
47
During Monitoring window, idle nodes are omni
Spatial Reuse in CaDMAC
A B
C
EF
D
![Page 48: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/48.jpg)
48
At the end of Monitoring window CaDMAC identifies unproductive links
Spatial Reuse in CaDMAC
A B
C
EF
D
![Page 49: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/49.jpg)
49
During Filtering window use spatial filtering
Spatial Reuse in CaDMAC
A B
C
EF
D
Parallel CommunicationsCaDMAC : 3 DMAC & others : ≤ 2Omni 802.11 : 1
![Page 50: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/50.jpg)
50
Network Capacity [TechReport ‘05]
Existing results show Capacity improvement lower bounded by
Results do not consider side lobes of radiation patterns
We consider main lobe and side lobe gains (gm
and gs)
We find capacity upper bounded by
i.e., improvement of
2
O
2
1
1
21
s
m
g
g
n
W
2
s
m
g
gO
CaDMAC still below achievable capacity
![Page 51: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/51.jpg)
51
CaDMAC cannot eliminate capture completely
Happens because CaDMAC cannot choose routes Avoiding capture-prone links A routing
problem
Discussion
YX
AB
![Page 52: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/52.jpg)
52
Routing using Directional AntennasIncorporating capture-awareness
![Page 53: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/53.jpg)
53
Motivating Capture-Aware Routing
YX
AB
YX
AB
D
S
Z DZ
S
Find a route from S to D, given AB exists Options are SXYD, SXZG
Capture No Capture
![Page 54: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/54.jpg)
54
1. Sum capture costs of all beams on the route Capture cost of a Beam j =
how much unproductive traffic incident on Beam j
2. Route’s hop count3. Cost of participation
How many intermediate nodes participate in cross traffic
Measuring Route Cost
X
DS
![Page 55: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/55.jpg)
55
Uroute = Weighted Combination of1. Capture cost (K)2. Participation cost (P)3. Hop count (H)
Weights chosen based on sensitivity analysis
Unified Routing Metric
ijipijrouteij
kroute HPU
![Page 56: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/56.jpg)
56
CaRP Vs DSR
1
2
34
![Page 57: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/57.jpg)
57
CaRP Vs DSR
![Page 58: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/58.jpg)
58
CaRP Vs DSR
![Page 59: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/59.jpg)
59
CaRP Vs DSR
![Page 60: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/60.jpg)
60
CaRP Vs DSR
![Page 61: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/61.jpg)
61
CaRP Vs DSR
![Page 62: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/62.jpg)
62
CaRP Vs DSR
![Page 63: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/63.jpg)
63
CaRP Vs DSR
![Page 64: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/64.jpg)
64
CaRP Vs DSR
DSR CaRP
CaRP prefers a traffic-free direction“Squeezes in” more traffic in given area
![Page 65: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/65.jpg)
65
Performance of CaDMAC
CaDMAC
DMAC
802.11
CBR Traffic (Mbps)
Ag
gre
gate
Th
rou
gh
pu
t (M
bp
s)
CMAC
![Page 66: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/66.jpg)
66
Throughput with CaRP CaRP +CaDMAC
DSR +CaDMAC
DSR +802.11
Ag
gre
gate
Th
rou
gh
pu
t (M
bp
s)
Topology Number
Random Topologies
![Page 67: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/67.jpg)
67
Research Contribution
Identified several new challenges
Designed MAC and Routing protocols MMAC, ToneDMAC, CaDMAC DDSR, CaRP Cross-Layer protocols – Anycasting Improved understanding of theoretical capacity
Developed prototype testbed
![Page 68: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/68.jpg)
68
Testbed Prototype [VTC 05, Mobihoc05Poster]
Network of 6 laptops using ESPAR antennas ESPAR attached to external antenna port Beams controlled from higher layer via USB
Validated basic operations and tradeoffs Neighbor discovery
•Observed multipath
•60 degrees beamwidth useful
Basic link state routing • Improves route stability
•Higher throughput, less delay
![Page 69: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/69.jpg)
69
Summary
Proliferation of wireless devices motivate better interference management
Most research assume omni antennas Energy radiated in all directions – inefficient
![Page 70: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/70.jpg)
70
Omnidirectional Antennas
Internet
![Page 71: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/71.jpg)
71
Summary
Our focus on exploiting antenna capabilities Several challenges appear Existing protocols incapable of leveraging benefits
Designed protocols at MAC and Network layer MMAC, ToneDMAC, CaDMAC Directional DSR, CaRP Analysed the upper bounds on capacity
Developed prototype testbed Capable of utilizing beamforming antennas
![Page 72: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/72.jpg)
72
Summary
Internet
![Page 73: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/73.jpg)
73
Other Work
Sensor Networks Reliable network-wide broadcast [submitted ICDCS]
Exploiting mobility as a carrier of gossip [StoDis 05]
K-Coverage problems
Location management in mobile networks Designed distributed algorithms [IPDPS], [Mobihoc]
Scheduling protocols for 802.11n Combination of CSMA + TDMA schemes [WTS 04]
![Page 74: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/74.jpg)
74
Future Work
Next generation radios (software, cognitive) PHY layer not be sufficient to harness flexibility
Example•When should a radio toggle between TDMA and CSMA
?
•Dynamic channel access needs coordination
Higher layer protocols necessary for decisions
![Page 75: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/75.jpg)
75
Future Work
Exploiting Diversity Opportunistically Especially in the context of improving
reliability
•Link diversity
•Route diversity
•Antenna diversity
•Channel diversity …
My previous work on Anycasting – a first step I intend to continue in this direction
S
A
B
C
D
![Page 76: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/76.jpg)
76
Future Work
Sensor Networks
Strong guarantees
Weak guarantees
Solu
tion C
om
ple
xit
ySensor networks ammenableto probabilistic guarantees.
Need to design protocols that exploit this possibility
![Page 77: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/77.jpg)
77
Future Work
Experimental Testbeds and Prototypes Evaluate protocols in real conditions Intend to build prototype testbed for sensor
and mesh networks
![Page 78: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/78.jpg)
78
Thank You
AcknowledgmentsProf. Nitin Vaidya (advisor)
Members of my research group
CollaboratorsRam Ramanathan (BBN)
Tetsuro Ueda (ATR Labs, Japan)Steve Emeott (Motorola Labs)
Lily Yang, Guoquing Li (Intel Labs)
![Page 79: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/79.jpg)
79
Wireless Networks
Gained popularity over last decade Cellular networks Mesh networks Wireless LANs
Several advantages Users can be mobile Low deployment cost Information access anytime-anywhere
![Page 80: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/80.jpg)
80
Capacity Result
Wireless network capacity is shared by users
Per-user capacity upper bounded by
Implication: Relaying better than shouting
n
WO
B
A
C
D
relay relay
![Page 81: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/81.jpg)
81
Modify
Similar to TCP on deafness – no Typo – reduscing 802.11 – say request to send Multihop in sensor MIMO – and multipath 1 slide on antenna beam/mode
Say “Antenna has 3 modes – omni, single, multi” Higher layer sets 1 mode, and direction before initiating
communication 802.11 just before DMAC 1 minute on MMAC, ToneDMAC, etc. Turning off beams has to be done before comm starts Say shortest hop first – then say DSR
![Page 82: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/82.jpg)
82
RTS = Request To Send
RTS
CTS = Clear To Send
CTS
IEEE 802.11 with Omni Antenna
D
Y
S
X
M
K
![Page 83: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/83.jpg)
83
Enhancing MAC [Mobicom02]
MMAC Transmit multi-hop RTS to far-away receiver Synchronize with receiver using CTS
(rendezvous) Communicate data over long links
![Page 84: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/84.jpg)
84
Routing with Higher Range [PWC03 Best Paper]
Directional routes offer Better connectivity, fewer-hop routes
However, broadcast difficult Sweeping necessary to emulate broadcast
Evaluate tradeoffs Designed directional DSR
![Page 85: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/85.jpg)
85
ToneDMAC’s Impact
Another possible improvement:
Backoff Counter for DMAC flows
Backoff Counter for ToneDMAC flows
time
Ba
cko
ff V
alu
es
![Page 86: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/86.jpg)
86
2-hop flow
DMAC
IEEE 802.11
Dea
fnes
s
![Page 87: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/87.jpg)
87
Neighbor Discovery
Non LOS and multipath important factors However, wide beamwidth (60 degrees)
reasonable envelope
Anechoic Chamber Office Corridor
![Page 88: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/88.jpg)
88
Route Reliability
Routes discovered using sweeping – DO links Data Communication using DD links Improved SINR improves robustness against
fading
![Page 89: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/89.jpg)
89
Optimal Carrier Sense Threshold
When sidelobe abstracted to sphere with gain Gs
T
Sidelobe Gs
Mainlobe Gd
Provided, optimal CS threshold is above the Rx sensitivity thresholdi.e., min {CS_calculate, RxSensitivity}
![Page 90: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/90.jpg)
90
Commercial Antennas …
Paratek (DRWin scanning smart antennas) Beamforming in the RF domain (instead of digital) Multiple simultaneous beams possible, each
steerable http://www.mobileinfo.com/news_2002/issue08/Paratek_Antenna.htm
Motia Inc. (Javelin appliqué to 802.11 cards) Blind beamforming in RF domain (< 2us, within pilot)
CalAmps (DirectedAP offers digital beamforming) Uses RASTER beamforming technology http://www.calamp.com/pro_802_directedap.html
![Page 91: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/91.jpg)
91
Commercial Antennas
Belkin (Pre-N smart antenna router – Airgo tech.) Uses 3 antenna elements for adaptive
beamforming http://www.techonline.com/community/tech_group/37714
Tantivy Communications (switching < 100 nanosec) http://www.prism.gatech.edu/~gtg139k/papers/11-03-025r0-WNG-bene
fitsofSmartAntennasin802.11Networks.pdf
![Page 92: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/92.jpg)
92
While node pairs communicate X misses D’s CTS to S No DNAV toward D
New Hidden Terminal Problem II
D
Y
S
X
DataData
![Page 93: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/93.jpg)
93
While node pairs communicate X misses D’s CTS to S No DNAV toward D X may later initiate RTS toward D, causing
collision
New Hidden Terminal Problem II
D
Y
S
X
Data
RTS
Collision
![Page 94: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/94.jpg)
94
Abstract Antenna Model
N conical beams
Any combination of beams can be turned on
Capable of detecting beam-of-arrival for received packet
![Page 95: Utilizing Beamforming Antennas for Wireless Multi-hop Networks](https://reader034.vdocument.in/reader034/viewer/2022051417/56814a86550346895db797f7/html5/thumbnails/95.jpg)
95
Source routing protocol (like DSR) Intermediate node X updates route cost from S -
X
Destination chooses route with least cost (Uroute) Routing protocol shown to be loop-free
Protocol Design
X
DS
C1
C2
C3
C5
USX
USD = USX + C2 + C5 + PD + 1