A Cross Layer MAC with Explicit Synchronization through Intelligent Feedback for Multiple Beam Anten...
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A Cross Layer MAC with Explicit Synchronization through Intelligent Feedback for Multiple Beam Antennas. Vivek Jain, Anurag Gupta Dharma P. Agrawal. Dhananjay Lal. ECECS Department University of Cincinnati {jainvk, guptaag, [email protected] Research and Technology Center

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Vivek jain anurag gupta dharma p agrawal

A Cross Layer MAC with Explicit Synchronization through Intelligent Feedback for Multiple Beam Antennas

Vivek Jain, Anurag Gupta Dharma P. Agrawal

Dhananjay Lal

ECECS Department

University of Cincinnati

{jainvk, guptaag, [email protected]

Research and Technology Center

Robert Bosch Corporation

[email protected]


Outline

Outline

  • Introduction

  • Multiple Beam Antennas

  • MAC Protocol Design Issues

  • The ESIF Protocol

  • Performance Evaluation

  • Conclusions


Introduction

Directional Antenna – Better Spatial reuse. But a node still unable to fully utilize “spatial bandwidth”.

Nodes in Silent Zone

E

C

C

G

G

X

A

B

A

B

F

H

F

D

H

D

Directional Communication

Introduction

Omnidirectional Antenna – Low Throughput in Wireless Ad hoc networks due to poor spatial reuse

Omnidirectional Communication


Introduction1

DATA

DATA

DATA

DATA

DATA

DATA

Introduction

  • Multiple Beam Antenna – Exploits spatial bandwidth fully

  • A node can initiate more than one simultaneous transmissions (or receptions).

A

E

D

B

F

C

G


Multiple beam antennas types

Interferer 3

top view (horizontal)

top view (horizontal)

Interferer 3

3

4

User 3

2

5

Interferer 1

Interferer 1

User 3

6

1

User 1

User 1

7

12

8

11

9

10

Interferer 2

User 2

User 2

Interferer 2

Switched array

Adaptive array

Wireless Local Area Networks

Cellular Communication Networks

Military networks

Applications

Multiple Beam Antennas - Types


Multiple beam antennas beam forming

Beam Formation

Direction of Arrival Estimation

Multiple Beam Antennas - Beam Forming

Therefore, a node can either transmit or receive simultaneously but not both.

… …


Ieee 802 11 dcf

IEEE 802.11 DCF

  • De-facto medium access control for wireless LAN and ad hoc networks

  • Originally designed for omnidirectional communication, its virtual carrier sensing (VCS) mechanism is enhanced for directional communication to include directional of arrival also.

Physical Carrier Sensing

DIFS

SIFS

Time

RTS

Data

Source

SIFS

SIFS

CTS

ACK

Destination

DIFS

RTS

NAV (RTS)

Other

NAV (CTS)

aSlotTime

NAV (Data)

Virtual Carrier Sensing

Defer access

RandomBackoff


Mac issues

DIFS

RTS

RTS

RTS

RTS

RTS

RTS

DIFS

RTS

RTS

DATA

CTS

RTS

DIFS

ACK

CTS

MAC – Issues

Concurrent Packet Reception with IEEE 802.11 DCF

A

E

DIFS

D

B

F

C

G

Conclusion: Eradicate the backoff after DIFS duration


Mac issues backoff removal

DATA

ACK

RTS

CTS

MAC Issues – Backoff Removal

  • Multiple transmitters, located in the same beam of common receiver, always get the same receiver schedule and thus initiate communication at the same time - collision

  • A node with very high data generation rate will overwhelm its receiver, without giving latter a chance to forward this traffic - fairness issue

  • All classes of service get same priority – QoS issue

Use p-persistent CSMA

A

DIFS

RTS

X

RTS

B

C

DIFS

A

B

C

DIFS

DIFS

Hold the transmitting node


Esif assumptions

ESIF – Assumptions

  • Nodes are equipped with multiple switched beam antenna array and can precisely calculate the Angle of Arrival (AoA) of the received signal

  • All nodes form non-overlapping multiple beams with equal gain so as to collectively span entire space

  • Beam shape is assumed as conical and benefits of nulling or the impact of side-lobe interference are not considered

  • A node can either transmit or receive data on multiple beams at the same time but not both

  • The channel is symmetric.


Esif enav

ESIF – ENAV

  • Every node maintains an ENAV:

    • The beam a neighbor falls within

    • Neighbor’s schedule - the duration until this neighbor is engaged in communication elsewhere

    • Whether a neighbor’s schedule requires maintaining silence in the entire beam

    • Number of data packets outbound for the neighbor

    • The p-persistent probability to use when talking to this neighbor


Esif cross layer data management

ESIF – Cross Layer Data Management

  • Using network layer information along with ENAV a node determines:

    • Whether a beam contains an active route

    • The number of potential transmitters in each beam

    • Until what time the node needs to maintain silence in a particular beam

  • Each node has a store-and-forward buffer for relaying data packets

  • Available buffer is used dynamically to form different queues for each beam - prevents head-of-the-line blocking


Esif design

ESIF – Design

  • ESIF piggybacks feedback onto control messages; RTS with Intelligent Feedback (RIF), and CTS with Intelligent Feedback (CIF), Schedule Update with Intelligent Feedback (SCH)

  • SCH identifier allows a neighbor to adjudge whether to defer transmission for only this node or for the entire beam

  • buffer-threshold to control priorities between receiver and transmitter modes

    • Reception gets priority as long as the buffer size remains under the threshold

    • If a node cannot actually initiate transmitter mode, the receiver still gets the priority

  • Priority switch solves problems of an overwhelmed receiver.

  • This also provides a mechanism to control the contribution of a node to end-to-end delays


Esif control message packet format

ESIF – Control Message Packet Format

  • Type field in Frame Controlis used toidentify a control message as RIF, CIF or SCH

  • Duration holds the estimated time of communication that the other nodes must backoff for;

  • Priority contains the priority of this request, and

  • p is the persistent probability which the other nodes should use when talking to this node.

Control packet (RIF/CIF/SCH) format


Performance evaluation

3

2

4

1

Directional Coverage Area

5

8

Omnidirectional Coverage Area

6

7

Performance Evaluation

  • Generation of packets is modeled as a Poisson process with the equal mean arrival time

  • IEEE 802.11 DCF based protocols are used for omnidirectional antenna (Omni), single beam directional antenna (Directional-NB) and MBAA (MMAC-NB), directional (Directional) and multiple-beam (Multibeam)

  • Directional-NB, MMAC-NB and ESIF protocols involve DVCS

  • ESIF is implemented with a buffer-threshold value of 1

Gains from spatial reuse only are considered

The Antenna Model


Esif basic operation

ESIF – Basic Operation


Simulation parameters

Simulation Parameters


Performance evaluation1

Performance Evaluation

B

A

  • Removal of contention window based backoff in ESIF does not affect long-term fairness

  • Both the transmitters get equal opportunity to transmit


Performance evaluation2

A

C

B

D

Performance Evaluation

  • ESIF enhances throughput by the priority switch between transmission and reception modes

  • ESIF is able to achieve concurrent data communications between node pairs A-B and C-D


Performance evaluation3

A

E

D

B

F

C

G

Performance Evaluation

  • ESIF is able to achieve CPR at common intermediate node D

  • Dynamic priority switch ensures data packets just received are transmitted (concurrently) in the next cycle, thus, maximizing throughput and minimizing delay


Conclusions

Conclusions

  • ESIF is the first attempt to achieve concurrent packet reception with on-demand protocols for MBAA

  • ESIF removes the contention window based random backoff in IEEE 802.11 DCF based protocols and uses embedded feedback to synchronize neighboring nodes

  • Allows nodes to receive or transmit multiple packets simultaneously in different beams

  • Cross layer information is used to guarantee long-term fairness

  • ESIF is a hybrid of synchronous and asynchronous on-demand medium access control


Vivek jain anurag gupta dharma p agrawal

Questions ???

Thank You!!!


Performance evaluation4

A

B

C

D

Performance Evaluation

  • Deafness and route coupling do not affect omni-protocols, but directional protocols experience performance degradation at higher loads.


Performance evaluation5

A

C

D

B

Performance Evaluation

  • Omnidirectional protocols overwhelms node C leading to data loss when the packet lifetime expires.

  • ESIF extracts the highest throughput among all protocols by using a proportional p value for p-persistent CSMA.


Performance evaluation6

G

J

B

D

A

F

C

E

I

H

Performance Evaluation

  • Directional protocols perform better at higher loads because of better spatial reuse.

  • ESIF takes advantage of CPR and CPT to achieve optimal performance


Performance evaluation7

D

E

C

B

A

Performance Evaluation

  • Node-based backoff protocols for multiple beam antennas achieve maximum throughput due to gains from concurrent packet transmissions

  • On-demand protocols does not yields optimal results for Complete-k topologies due to synchronization losses


Performance evaluation8

Performance Evaluation

  • Multiple beam omni-directional protocols expend more energy due to omni-directional transmission of control messages.

Energy expended in random and compete-5 topologies


Ieee packet formats

IEEE – Packet Formats

Frame control field for control messages


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