Energy and Spatial Reuse Efficient Network-Wide Real-Time

Data Broadcastingin Mobile Ad Hoc NetworksB. Tavli and W. B. Heinzelman

Julián Urbanojurbano@vt.edu

Overview

• Introduction

• Background

• MH-TRACE

• NB-TRACE

• Simulation

• Conclusions

Introduction

Network-Wide Real-TimeData Broadcasting

• Military networks– Broadcast– QoS– Can not restrict to single-hop

• Energy efficiency, efficient spatial reuse and QoS are mandatory– No architecture proposed so far addressing all them– Network-wide Broadcasting through Time Reservation

using Adaptive Control for Energy efficiency (NB-TRACE)

– Based on MH-TRACE

Background

Energy Dissipation

• Different Categories– Transmit mode– Receive mode– Idle mode– Carrier sense mode– Sleep mode

Energy Dissipation (II)

• How to Achieve it?– Unnecessary carrier sensing– Idle energy dissipation– Overhear irrelevant packets– Transmit energy dissipation– Reduce overhead

Energy Dissipation (III)

• Before– IEEE 802.11 supports ATIM

• Ad Hoc Traffic Indication Message• Reduces idle time but doesn’t address overhear• Focused on unicast traffic

– SMAC• Periodically shuts off radios to reduce idle time• With low traffic outperforms IEEE 802.11

• TSMAC and RSMAC

Energy Dissipation (and IV)

• About overhearing– Information Summarization (IS) packet

• RTS/CTS packets on top of IEEE 802.11– Power Aware Multiaccess protocol with Signaling for Ad

Hoc Networks (PAMAS)

• Redundant IS packet? Go sleep!

• Delay, throughput and transmit dissipation– There is an optimum transmit radio DOP

• Beyond DOP multi-hop outperforms single-hop• Great for constant transmit range radios

Efficient Spatial Reuse

• # retransmissions required for a packet to be received by every node

• Algorithms– Non-coordinated– Fully coordinated

• Create a Minimum Connected Dominating Set

– Partially coordinated• Create a MCDS, almost

Efficient Spatial Reuse (II)

• Non-coordinated– Flooding

• With Random Access Delay (RAD) from 0 to TRAD

– Gossiping• With RAD and probability pGSP

Efficient Spatial Reuse (III)

• Fully coordinated algorithms– Based on global info– NP-problem

Efficient Spatial Reuse (and IV)

• Partially coordinated algorithms– Based on local info– Counter-Based Broadcasting (CBB)

• Count packets until broadcast timer expires

• If received less than NCBB retransmit

– Distance-Based Broadcasting (DBB)• Based on received power strength

• If closest received is beyond DDBB retransmit

Quality of Service

• Necessitates– Low delay

• # hops traversed and contention level

– Low jitter• Deviation from periodicity of packet receptions

– High Packet Delivery Ratio (PDR)• Drops and collisions

• Parameters– TDROP = 150ms– Packet Generation period (TPG)– PDR = 95%

Quality of Service (and II)

• Highly related to energy efficiency

• Centralized Control?– Not practical in Mobile Ad Hoc– High overhead

• Clustering with Cluster Heads (CH)– Schedule the channel access– Some nodes can sleep

MH-TRACE

MH-TRACE

• Multi-Hop Time Reservation using Adaptive Control for Energy efficiency

MH-TRACE (and II)

• Gain access through the contention slots• If gets access fill out the corresponding IS slot• Transmit in the corresponding data slot…• …until it finishes? Starvation?

• Network synchronization through GPS

NB-TRACE

Design Principles

• Integrate energy-efficiency in MH-TRACE

• Flooding– IS = (IDnode, IDpacket)

– Go sleep!

• Problems with other algorithms– MH-TRACE is application-based

• NB-TRACE floods the network and prunes

• Maintain a Control Dominating Set (CDS)

Overview

• Time Division Multiple Access (TDMA)• Initially flood to the whole network• ACK the upstream nodes

• If no ACK in TACK cease rebroadcast

• Algorithm– Initial Flooding (IFL)– Pruning (PRN)– Repair Branch (RPB)– Create Branch (CRB)– Activate Branch (ACB)

Initial Flooding

• Broadcast packets to one-hop neighbors• Contend channel access and rebroadcast

– Eventually every node has received

• IFL IDD=1 for TIFL so every node wakes up

Pruning

• 3 states for nodes– Passive– Active– Activate Branch (ACB)

• Problem: stop ACKing from outermost leaf– Eventually, only the source node broadcasts

• Solution: CHs always rebroadcast– Maintain the Non-Connected Dominating Set

Pruning (and II)

• Eventually 1, 3, 5 and 7 go to passive mode– 0, 2, 4 and 6 make up the broadcast tree

• 5 stops rebroadcast after TACK, 3 stops after 2TACK, 1 stops after 3TACK

• Problem: the nodes are mobile– Re-flood again? Not efficient

Repair Branch

• Mobility causes CHs to go out and come in– New CH stays in startup mode– Mark the beacon packet– Every node rebroadcasts it

• Problem: broken trees

Create Branch

• If a node detects an inactive CH in TCRB

– Switch to active and rebroadcast

Activate Branch

• If a node does not receive for TACB

– Go to ACB mode

– Send ACB packet with pACB

• Into the IS slots in order not to modify MH-TRACE

– If a node receives an ACB packet• Switch to active and begin relying

– If there is nothing to send, they go to ACB mode

– If an ACB node receives data• Switch to active and begin relying

Packet Drop Threshold

• TDROP used throughout the network

• TDROP-SOURCE used at the source node

• TDROP-SOURCE=TPG

Simulations

Overview

• QoS and energy dissipation on– NB-TRACE– MH-TRACE with

• Flooding

– IEEE 802.11 and SMAC with• Flooding• Gossiping• CBB• DBB

Environment

• Data packets of 110bytes• Node mobility speed from

0.0 to 5.0m/s– 2.5±0.2m/s– 2.2 ±0.4m/s

• 1km wide network• 80 nodes• Data rate of 32Kbps

Performance Analysis

• 3B = IFL, PRN and RPB• 4B = IFL, PRN, RPB and CPB

Performance Analysis (II)

• Time– 81.4% in sleep– 16.7% in idle– 2.8% in transmit, receive and carrier sense

• 19.4% of the total energy dissipation

• Energy– 82.4% packet transmissions– 7.5% IS transmissions– 10.1% other control packet transmissions

Performance Analysis (III)

Performance Analysis (and IV)

Varying the Data Rate

• Adjust the superframe size• Adjust # of data slots per frame• Superframe time≈TPG=25ms.

Varying the Data Rate (and II)

Varying the Node Density

• 1 by 1km network with 48Kbps

Conclusions

Overview

• Most of the work to date targeted at deducing transmit energy dissipation only

• NB-TRACE also targets receiving, idle, sleep and carrier sense dissipation

• According to the 2 (experimental) energy models, transmit energy is not as dominant as thought

Quality of Service

• Satisfies QoS requirements under several different scenarios– Robustness of the broadcast tree– Maintenance of the NCDS– Cross-layer design– Automatic renewal of channel access

Energy Dissipation

• It is way lower– Coordinated channel access– Packet discrimination– Lower Average Retransmitting Nodes (ARN)

Delay

• It is larger with small networks– Restricted channel access

• Maintains a regular delay with bigger networks

• It is much lower with larger networks– High node density– High data rates

Jitter

• Lower to all but MH-TRACE– Channel access granted by CHs after contend

Spatial Reuse

• Better than the others– Robustness of channel access– Full integration with MAC layer– IEEE‘s MAC doesn’t prevent excessive

collisions

• No data!

Energy Model

• Energy savings are related to the model

• Some radios do not support sleep mode or the dissipation difference is small– However, NB-TRACE performs well

Future Work

• Extend TRACE to multicast and unicast– The blocks are reusable– CHs can become multicasting group members

as they always broadcast

• Realistic environments with channel errors– MH-TRACE is shown to outperform IEEE