1. Submission Title: Pre-Arbitrated Slot Allocation (PASA) MAC Protocol
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: Pre-Arbitrated Slot Allocation (PASA) MAC Protocol
Date Submitted: 9 Nov., 2004
Source: [Hyung Soo Lee (1), Cheol Hyo Lee (1), Dan Keun Sung (2), Dong Jo Park (2), Joon Yong Lee (3),
Chang Yong Jung (2), Jo Woon Chong (2), Min Jeong Kim (2), Sung Yoon Jung (2), Mi Kyung Oh (2)]
Company: [(1) Electronics and Telecommunications Research Institute (ETRI) (2) Korea Advanced Institute of Science and Technology (KAIST) (3) Handong Global University (HGU)]
Address: [(1) 161 Gajeong-dong, Yuseong-gu, Daejeon, Republic of Korea (2) Guseong-dong, Yuseong-gu,
Daejeon, Republic of Korea (3) Heunghae-eup, Buk-gu, Pohang, Republic of Korea]
Voice: [(1) , (2) (5439), (3) ], FAX: [(2) ]
[(1) (2) (3)
Abstract: [This document proposes preliminary proposal for the IEEE alternate PHY standard]
Purpose: [Preliminary Proposal for the IEEE a standard]
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is
not binding on the contributing individual(s) or organization(s). The material in this document is subject to
change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or
withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be
made publicly available by P802.15

2. Pre-Arbitrated Slot Allocation (PASA) MAC Protocol
ETRI-KAIST-HGU
Republic of Korea

3. Contents CSMA/CA in a UWB Impulse Environment
Requirements for a New Energy-Efficient MAC Protocol
Pre-Arbitrated Slot Allocation (PASA) MAC Protocol
Performance Comparisons of PASA and CSMA/CA
Simultaneously Operating Piconets (SOP)
Conclusions

4. CSMA/CA in a UWB Impulse Environment
Difficulties in Carrier Sensing
Detection of UWB Impulse signals
Integration and decision  detection error and delay
Longer Clear Channel Assessment (CCA) detection time
(d=30m, False Alarm Probability =0.1)
Relatively Large Amount of Power Consumption
Carrier sensing (CCA) overhead
Tx, Rx, CCA, and idle states for the most of contention access period (CAP)
CCA Detection Time
1 ms
2 ms
4 ms
8 ms
CCA Detection Probability
0.37
0.53
0.77
0.92

5. Requirements for a New Energy-Efficient MAC Protocol
No Carrier Sensing
No CCA overhead
Reduced Number of Node States
Tx, Rx, and sleep
Group Management
Support for a large number of nodes
Traffic load balancing
Very Low User Activity
Low Complexity
Low Cost
Contention Access Period and Contention Free Period

6. Pre-Arbitrated Slot Allocation (PASA) MAC Protocol
Superframe Structure
Beacon Period
Contention Access Period (CAP)
Pre-Arbitrated Slot Allocation (PASA)
Contention Free Period (CFP)
Time Division Multiple Access (TDMA)
Beacon
CAP
CFP
PASA
TDMA
Active
Inactive

7. Pre-Arbitrated Slot Allocation (PASA) MAC Protocol (Cont’d)
Pre-Arbitrated Slot Allocation for Each Group
No CCA
Elimination of CCA and idle states
Grouping Nodes
Support for a large number of nodes
Efficient Energy Management
Active state only if nodes transmit or receive frames
Group Acknowledgement via the next available beacon
Hierarchical Backoff Algorithm
Intra-superframe backoff : random slot selection in the superframe
Inter-superframe backoff : binary exponential superframe backoff

8. Pre-Arbitrated Slot Allocation (PASA) MAC Protocol (Cont’d)
Operation
Random
Slot Selection
Random
Slot Selection
Pre-Arbitrated
Slot Allocation
CAP

9. Node States in Both PASA and CSMA/CA
Node States in PASA
Tx : transmit data
Rx : listen to beacon, receive data
Sleep : except for Tx and Rx states
Node States in CSMA/CA
Rx : listen to beacon, receive ACK, and receive data
CCA : perform CCA
Idle : ready to transmit or receive
Sleep : inactive state

10. Superframe Structure For Performance Evaluation
Active
Inactive
CAP
CFP
PASA
TDMA
BEP =
256 (ms)
CAP = 3072 (ms)
CFP = 768 (ms)
SD = 4096 (ms)
BI = (ms)
Assumptions
Tb = 1 (ms), TimeSlot (TS) = 256 (ms)
Superframe Duration (SD) = 4096 (ms)
Beacon Interval (BI) = 8192 (ms)
Beacon extension period (BEP) : 1 superframeslot = 256 (ms)
CAP : 12 superframeslots = 3072 (ms)
CFP : 3 superframeslots = 768 (ms)
FER : 0.08

11. Power Consumption Model (Example)
Power Consumption Assumed for Various Node States
MAC
Power State
*Zigbee
CSMA/CA
PASA
Tx state
31 mW
Rx state
35 mW
CCA state -
33 mW
Idle state
30 mW
Sleep state
10 mW
* G. Lu, B. Krishnamachari, and C.S. Raghavendra,”Performance Evaluation of the
IEEE MAC for Low-Rate Low-Power Wireless Networks”, EWCN ‘04

12. Performance Measures Throughput # of Bits per Energy (bits/Joule)
Successfully transmitted bits per second
Focus on the CAP period
# of Bits per Energy (bits/Joule)
Average Delay
From the frame generation time to the reception time of ACK for successful frame transmission
: power consumption in state for node
: steady state probability of state for node
: the number of sensor nodes

13. Performance Comparisons of PASA and CSMA/CA (1)
Throughput
Channel activity factor per node : 10-3
Channel activity factor per node : 10-4

14. Performance Comparisons of PASA and CSMA/CA (2)
Bits per Energy (bits/mJ)
Channel activity factor per node : 10-3
Channel activity factor per node : 10-4

15. Performance Comparisons of PASA and CSMA/CA (3)
Average Delay
Channel activity factor per node : 10-3
Channel activity factor per node : 10-4

16. Simultaneously Operating Piconets (SOP)
Time Division
Operating bandwidth
GHz can be fully used (UWB pulse)
Configuration of SOPs
Self configuration of SOPs is possible by scanning the channel
Piconet #1
Active
Inactive
Piconet #2
Piconet #3

17. Conclusions Pre-Arbitrated Slot Allocation (PASA) MAC Protocol
No carrier sensing
Reduced number of node states
Tx, Rx, and sleep states
Active only if nodes transmit or receive frames
Scalability
Group management
Energy efficiency at the cost of delay
Candidate for a MAC protocol based on UWB impulse radio