cascading :
DESCRIPTION
EbT. CtS. CtS link. CC1010 sender. CC1010 receiver. Implementation. Energy-Efficient Communication Strategy for Wireless Sensor Networks. Yujie Zhu and Raghupathy Sivakumar GNAN Research Group, Georgia Tech. Example: 10Mbps data rate, 10 bit data packet size - PowerPoint PPT PresentationTRANSCRIPT
Cascading:
An Overview of the Strategy
Yujie Zhu and Raghupathy Sivakumar
GNAN Research Group, Georgia Tech
Energy-Efficient Communication Strategy for Wireless Sensor Networks
Implementation
Point-to-point link, one sender, one receiver CtS strategy is used to send randomly generated data packets Both sender and receiver are implemented using RF transceiver modules Chipcon CC1010 – single chip RF transceiver
Multiplexing:
Fast-forwarding:
The energy consumed for transmitting each bit of datadecreases inverse linearly with data packet size
Motivation:
Need for energy-efficient communication from light sensors to sink Traditional communication strategy conveys information between the sender and the receiver using energy (EbT) only
Energy consumption is keb, where k is the length of the bit-stream and eb is energy per bit
Can we use time as an added dimension to convey information?Communication through Silence (CtS):
A new communication strategy that conveys information using silent periods in tandem with small amount of energy Procedure:
Sender interprets the information to be transmitted as a data value Sender transmits start signal Receiver starts to count from 0 upon receiving start signal Sender and receiver are synchronized in counting clock Sender transmits stop signal when receiver counts up to the desired value Information delivered!
The energy consumption for CtS is always 2eb irrespective of the amount of information being sent
97 !
START
1 0 0 0 0 1 1
97
97 !
1 0 0 0 0 1 1 1 0 0 0 0 1 1
97
STOP
1 2 ….
EbT
CtS
The Energy Throughput Tradeoff
The time taken to transmit a packet
of s bits is 2s using Cts The throughput of CtS decreases as s/ 2s
Example:10Mbps data rate, 10 bit data packet sizeEnergy improvement: 5 timesEffective throughput: 10Kbps The CtS strategy incurs exponential throughput decrease
Optimization Strategies – Throughput Improvement
Two or more contending sender-receiver pairs can transmit at the same time as along as the start/stop signals do not overlap Enabled by the typical long silent intervals between start and stop signals in CtS Not possible in EbT since a sender-receiver pair has to occupy the channel exclusively during transmissions
CtS with Multiplexing
C-Dstart
C-D stop
2
2
4 C-Dstart
C-D stop
A-Bstart
A-BstopBasic CtS
10 time slots!
6 time slots !
A-Bstart
A-Bstop
Consecutive data values that are monotonically increasing or decreasing can be sent in a combined “signal train” consist of one start signal, multiple intermediate signals and one stop signal instead of multiple consecutive start/stop signals The same counting process can be used for multiple packets at the same time for CtS Not possible in EbT since overlapped data packets confuse the receiver
Basic CtS
A-Bstart
A-Bstop
3A-Bstart 1
A-Binterme
diate
CtS with Cascading
3
12 time slots!
7 time slots !
5A-Bstart 2
A-Bstop 2
A-Bstop1
For multihop CtS communication, a relay node can forward start/intermediate signals before the stop signal is received Enabled by the separable signals of each packet and possibility of simultaneous counting in CtSNot possible in EbT because a packet has to be received in full before forwarding to ensure content integrity
Basic CtS[t1 t5] [t7 t11]
[t2 t6] [t8 t12]
[t13 t17]
[t14 t18]
CtS with Fastforwarding
[t3 t7]
[t4 t8]
[t5 t9]
[t6 t10]
S DR1 R2
[t1 t5]
S DR1 R2
[t2 t6]
18 timeslots !
10 timeslots !
Performance Evaluation of Optimized CtS :
0
1000
2000
3000
4000
5000
6000
7000
0 10 20 30 40 50 60
Path Length (hop)
En
erg
y (E
b/b
it) CtSmfc EbT
The throughput of integrated CtS is up to twice that of EbT The energy consumption of EbT increases faster with path length than
integrated CtS
Summary:The energy-delay trade-off of basic CtS strategy can be alleviated by Proper combination of optimization strategies Adaptation of parameters
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 10 20 30 40 50 60
Path Length (hop)
Th
rou
gh
pu
t (b
it/b
it s
lot)
CtSmfc EbT
Protocol Design:
Test bed Implementation:
Hardware design MAC layer solutions: reliability, addressing, sequencing
CC1010 sender
CC1010 receiver
CtS link