Prioritized QoS Framework – Network Entry for IEEE 802.16m
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number: IEEE S802.16m-08/1046
Date Submitted: 2008-09-09
Source
An Nguyen
D. J. Shyy
An.P.Nguyen@dhs.gov
djshyy@mitre.org
Venue: MAC: Network Entry
In response to IEEE 802.16m-08/033, Call for Contributions and Comments on Project 802.16m System Description Document (SDD)
Base Contribution: C802.16m-08/1046r1
Purpose: Request consideration of prioritized QoS framework in network entry contained herein for the 802.16m SDD
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Outline
• Introduction
• Prioritized QoS framework in connection
establishment and maintenance
• SDD text proposal
Objective
• Priority access is one of the important
requirements for Emergency
Telecommunications Service (ETS)*
• IEEE 802.16m has requirements on priority for
the government and public safety
– Section 5.8 of IEEE 802.16m-07/002r4
• “IEEE 802.16m shall be able to support public safety first
responders, military and emergency services such as callprioritization, preemption, push-to-talk”
*“Overview of Standards in Support of Emergency Telecommunication Service (ETS),” ATIS-pp-0100009, November 2006.
Radio Access Congestion Points
ASN
16e MS
16m MS
R1
R1
16m BS
R6
R6
16m MS
R1
16m BS
• Contention-based radio resource
• Initial ranging
• Bandwidth request
• Allocation-based radio resource
• Service flow admission
ASN Gateway
802.16e Network Entry Procedure
•
•
•
•
•
•
•
•
Scanning
Obtaining parameters
Initial ranging
Exchanging capabilities
Authentication
Registration
IP connectivity
Creating transport connection (Adding service,
service flow admission)
• Bandwidth Request for admitted service flow
802.16m Prioritized Contention Resolution
• Bandwidth request and initial ranging use contention-based
scheme to access the network. The ranging and bandwidth
requests use PN sequences (codes) to mitigate collisions.
• Our concerns
– First, based on the WiBro deployments, their capacity is actually the
bottleneck of the network.
– Second, configurations for initial ranging and bandwidth request can be
specified only on a per sector basis, i.e., they cannot be defined on a per
user class per sector basis. As a result, no service differentiation can be
provided to MSs for initial ranging or bandwidth request within a
sector.
– We propose to have the parameters for initial ranging and bandwidth
request to be specified on a per user class per sector basis for IEEE
802.16m.
• In the next few slides, we analyze the performance of
prioritized initial ranging and illustrate its benefits
Two Types of Code Interference
•
•
Multiple users choose the same code (code
collision)
Excessive interference at the receiver (code
interference)
–
Code interference threshold (4 or 8)
Mitigation Techniques
•
Dedicated code
–
•
Orthogonal code; this solves the code collision, but does
not resolve code interference.
Dedicated initial ranging slot
–
•
Dedicated subchannel (orthogonal frequency) and
dedicated symbol (orthogonal time); this solves code
interference.
Time between dedicated initial ranging regions
–
Dedicated frame (orthogonal time); this solves code
interference.
Simulation Results I
Initial Raning Performance Analysis for 802.16e/m Networks
1
0.9
0.8
0.7
Probability
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
Total IR Arrival Rate (= lt where t = 5 ms)
overall IR success rate (I.2)
reg interference (I.1)
cc pri to pri (I.1)
regular IR success rate (I.1)
overall interference (I.2)
cc pri to reg (I.1)
priority IR success rate (I.1)
cc all to all (I.2)
cc reg to pri (I.1)
pri interference (I.1)
cc reg to reg (I.1)
In Case I.1, there is only one initial ranging slot, but regular and priority users have their dedicated codes. In Case I.2, there is only
one initial ranging slot, but regular and priority users share the code space. Case I.1 performs worse than case I.2 which means if
there are no orthogonal resources in time and/or frequency (e.g. initial ranging slot) for priority users, division of code space does
not help. The reason is that since the dominating interference factor is excessive interference, division of the code space does not
provide any benefit.
8
Simulation Results II
Initial Raning Performance Analysis for 802.16e/m Networks
1
0.9
0.8
0.7
Probability
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
Total IR Arrival Rate (= lt where t = 5 ms)
priority IR success rate (II.1)
pri interference (II.1)
regular IR success rate (II.1)
cc reg to reg (II.1)
reg interference (II.1)
cc pri to pri (II.1)
In Case II.1, one initial ranging slot is for regular users while another initial ranging slot is dedicated to priority users. The
probability of success for priority initial ranging can be maintained about 90% for all initial ranging arrival load.
Simulation Results III
Initial Raning Performance Analysis for 802.16e/m Networks
1
0.9
0.8
0.7
Probability
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
Total IR Arrival Rate (= lt where t = 5 ms)
priority IR success rate (III.1)
reg interference (II.5)
regular IR success rate (III.1)
cc reg to reg (III.1)
pri interference (III.1)
cc pri to pri (III.1)
Case III.1 assigns 7 frames (out of every 8 frames) for regular user traffic and 1 frame (out of every 8 frames) for priority user
traffic. Although the probability of success for priority initial ranging degrades with higher initial ranging load, its performance is
better than that of regular user.
Observation
• In most of the cases, the excessive interference
is the dominating factor of interference. As a
result, division of the code space (without
dedicated slot or time for priority users) does
not provide any benefit. Division of code
space must be accompanied by dedicated
time/frequency resources.
SDD Text Proposal
[---------------------------------------------------Start of Text Proposal--------------------------------------------------]
Section 10 Medium Access Control Sub-Layer
10.x Network Entry
Assign one or more dedicated initial ranging slot for regular user and one dedicated initial ranging slot for priority user for a larger
channel bandwidth (e.g. 10 MHz). Also assign a set of dedicated codes for regular user initial ranging and another dedicated set for
priority user initial ranging.
Optionally, assign one or more dedicated initial ranging frames for regular user and one dedicated initial ranging frame for priority
user for a smaller channel bandwidth (e.g. 5 MHz).
[---------------------------------------------------End of Text Proposal--------------------------------------------------]