Cross-evaluation results for network-initiated network entry proposals
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16p-11/0233
Date Submitted:
2011-09-18
Source:
Jinsoo Choi, Youngsoo Yuk, Jin Sam Kwak
Email: js.choi@lge.com
LG Electronics
Re:
To provide the evaluation results for network-initiated network entry proposals
Abstract:
This contribution provides the evaluation results for network-initiated network entry proposals
Purpose:
To provide the evaluation results for network-initiated network entry proposals
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1
Evaluation assumption
 Basic evaluation assumptions follow the network entry
evaluation guideline document. Beside the guideline,
followings are more assumed for the details.
• Paging cycle: 1s, 2.5s, 5s (For correct performance comparison, assumi
ng on-going ranging load by consecutive paging intervals)
• Access rate: 40/s, 60/s, 80/s
• Different initial backoff window size: 4, 8, 16, 32, 64, 128, 256, 512, 102
4
• Backoff selection schemes
 A (The proposal from C802.16p-11/0142r1): Random backoff selection
starting with initial K backoff window size and raging retrials with 2^x
increasing window size
 B (The proposal from C802.16p-11/0180r1 excluding device specific
parameter scheme): Random backoff selection starting with initial K
backoff window size and raging retrials with 2^x decreasing window size
(min: 2) and start point alignment of backoff window
• Performance metric: Minimum average delay to meet the given
success rate, for the successful devices
Evaluation results
Terms
A
B
Targeting success rate
over 99%
over 99%
Initial backoff window size
4
64
Average delay (required frames)
0.51 s (102 frames)
0.3s (60 frames)
Table-1: Access rate = 40/s, paging cycle = 1 s
Terms
A
B
Targeting success rate
over 99%
over 99%
Initial backoff window size
8
256
Average delay (required frames)
1.23 s (246 frames)
0.98s (196 frames)
Table-2: Access rate = 40/s, paging cycle = 2.5 s
Terms
A
B
Targeting success rate
over 99%
over 99%
Initial backoff window size
16
512
Average delay (required frames)
2.55 s (510 frames)
1.96 s (392 frames)
Table-3: Access rate = 40/s, paging cycle = 5 s
3
Evaluation results (cont’d)
Terms
A
B
Targeting success rate
over 98%
over 98%
Initial backoff window size
16
128
Average delay (required frames)
1.22 s (244 frames)
* 0.99s w 94%
0.58 s (116 frames)
Table-4: Access rate = 60/s, paging cycle = 1 s
Terms
A
B
Targeting success rate
over 98%
over 98%
Initial backoff window size
128
256
Average delay (required frames)
4.51 s (902 frames)
* 2.36s w 91%
1.17s (234 frames)
Table-5: Access rate = 60/s, paging cycle = 2.5 s
Terms
A
B
Targeting success rate
over 98%
over 98%
Initial backoff window size
128
512
Average delay (required frames)
7.64 s (1528 frames)
* 4.74s w 91%
2.33 s (466 frames)
Table-6: Access rate = 60/s, paging cycle = 5 s
*: delay and success rate
within a paging cycle
4
Evaluation results (cont’d)
Terms
A
B
Targeting success rate
over 90%
over 90%
Initial backoff window size
128
256
Average delay (required frames)
4.16 s (832 frames)
1.55 s (310 frames)
Table-7: Access rate = 80/s, paging cycle = 1 s
Terms
A
B
Targeting success rate
over 90%
over 90%
Initial backoff window size
128
512
Average delay (required frames)
9.74 s (1948 frames)
2.86 s (572 frames)
Table-8: Access rate = 80/s, paging cycle = 2.5 s
Terms
A
B
Targeting success rate
over 90%
over 90%
Initial backoff window size
128
1024
Average delay (required frames)
15.3 s (3060 frames)
5.57 s (1114 frames)
Table-9: Access rate = 80/s, paging cycle = 5 s
5
Summary
 Performance comparison
• For all cases with various paging cycle and access rate, B scheme
shows less delay to satisfy the given success rate.
• Up to 60/s access rate, the overlapped ranging trial events (i.e. exceed
to the next paging interval), which actually affect on the access
performance in paging scenario, doesn’t occur in B scheme.
 Conclusion
• In paging scenario, many devices throng to the start point of paging
interval for ranging transmission. With small initial backoff window,
each failed ranging trial raises next ranging retransmission and
competition with devices in next paging cycles. As the access rate
increases, the competition will grow. This would not be a good
situation.
• In network-initiated network entry scenario, BS can set the proper
initial backoff window size based on the number of devices. Based on
that, the B scheme can effectively reduce the delay for successful
access and avoid the aforementioned situation as possible.
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