1 a new qos architecture for ieee 802.16 and spec. instruction speaker:93598009 ming-chia hsieh...
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A new QoS Architecture for IEEE 802.16 and Spec. Instruction
Speaker:93598009 Ming-Chia HsiehDate:2005/05/03
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Outline
Introduction Spec. New Qos Architecture 802.16a brief introduction Conclusion
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Introduction
802.16– Fast Deployment– Cost Savings– Support Quality of Service
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FRAMEWORK
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Outline
Introduction Spec. New Qos Architecture Conclusion
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Spec.
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Spec.
Communicate path – Uplink Channel (SS to BS)—
TDMA UL-MAP
– Downlink Channel (BS to SS) Broadcast
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Spec.
TDMA
mini-slots called Time-Division Multiple Access
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TDD frame structure
Symbol Rate: range 10~32M Baud, increments of 100k Baud
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Spec.
Uplink Channel– Uplink Channel Descriptor
Configuration Change Count– Determine whether the content is changed
Mini-Slot Size– Units of Physical Slot, Allowable n=2m
Uplink Channel ID– Arbitrarily Chosen by the BS– Unique within the MAC-Sublayer domain
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Spec
Uplink Channel (Cont.)– Uplink Map (UL-MAP)
Allocates access to the uplink channel
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Step to enter the network
BS
SSSCAN for a downlink channel
Downlink channel
parameter
DL-MAP
DCD
parameter
Adjust local parameter
Authorize/key exchange
Management msg
SBC-REQ
Control by BSIP
Establish time of day
Configuration information
REG-REQ
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Channel Access
BS
SS
Downlink channel
1 2 3 4 5 6 7
DATA
DL-MAP
Uplink Channel
UL-MAP
Time slot
DATA
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Spec.
Downlink Channel– Downlink Channel Descriptor (DCD)
Transmitted by the BS Define the characteristics of a downlink physical
channel
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Spec.
Downlink Channel– Downlink Map Parameter
PHY Synchronization
DCD Count– Match the DCD
Base Station ID– 48-bit
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Spec.
Qos ( Quality of Service )– Associate a packet with a service flow– Service Flow: unidirectional flow of packets that
provides a particular Qos
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Spec.
Support Quality of Service
Unsolicited Grant Service—UGS
Real-Time Polling Service—rtPS
Non-Real-Time Polling Service—nrtPs
Best Effort—BE
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Spec.
QoS types– UGS
Real-time service flows Periodic, fixed size grants Avoid overhead and latency of frequent SS redundant Meet the continuous need of service flow T1 / E1 / VoIP
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Spec.
Qos Types (Cont.)– rtPS (Real-Time Polling Service)
Real-time service flows Variable size data MPEG
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Spec.
QoS types– nrtPS
Non real-time service flow Variable size data
– BE Best Effort﹝ ﹞ Efficient service to best effort
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Spec.
Bandwidth allocation and request– Each SS is assigned 3 dedicated CID for different
level of QoS
– Incompressible constant bit rate UGS can’t reallocate bandwidth
– DAMA services are given resources on a demand assignment basis
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Spec.
Mode of grant of bandwidth request– GPSS Grant per Subscriber Station Mode﹝ ﹞
Bandwidth request are addressed to SSs Smaller UL maps Allow more intelligent SS
– GPC Grant per Connection﹝ ﹞ Bandwidth request are addressed to CIDs
– 這二個MODE在 802.16a中刪除了
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Outline
Introduction Spec. New Qos Architecture Conclusion
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Qos of IEEE 802.16Admission Control undefined by IEEE 802.16
Uplink BandwidthAllocation Scheduling
Uplink Scheduling for UGS defined by IEEE 802.16
Uplink scheduling for rtPS, nrtPS and BE service undefined
by IEEE 802.16
Traffic
Connection Classifier
UGS rtPS nrtPS BE
scheduler
Connection Request
ConnectionResponse
BW RequestMessage
Data packets
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New Qos Architecture
Admission Control
Uplink BandwidthAllocation Scheduling
Data Packet Packet Module
Traffic Management Table
Packet Allocation Module
Data Packet Analysis Module
Traffic
Connection Classifier
UGS rtPS nrtPS EE
Scheduler
Connection Request
ConnectionResponse
Data packets
BW requestMessage
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New Qos Architecture
Before establish connection SS set connection request to BS Admission control part of the BS decides to
accept or reject BS provide necessary information to SS
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New Qos Architecture
After establish Enforce the traffic on the contract BS update the traffic management table BS generate UL-MAP in downlink subframe SS transmits packets according to the UL-M
AP
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New Qos Architecture
Uplink Scheduler of SS– Transmit data PDU using uplink data slot granted
by BS.– UGS append virtual packet arrival time of rtPS– DPAM ( Data Packet Analysis Module ) receive rt
PS deadline information from SS.– Packet deadline=arrival time + maximum delay re
quirement of the connection
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New Qos Architecture
Uplink Scheduler of SS (Cont.)– nrtPS uses either contention-free or contention m
od.
– BE uses only contention mode
– BS controls contention mini-slot size in frame.
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New Qos Architecture
Uplink Bandwidth Allocation Scheduling– DPAM of BS separates UGS data and virtual pac
kets arrival time of rtPS– Traffic Management Module manages the informa
tion to decide the Poll order of next time
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New Qos Architecture
Backoff Procedure– BS broadcast a common back-off window size “B”
– SSs will randomly choose a reservation slot numbered between 1 and B to transmit its request
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Channel utilization analysis
K Classes Arrival events are mutual independent C denotes the server capacity and channel
utilization for each class I
C=p1+p2+p3+……pi ,C<=1
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Channel utilization analysis
λK: offered load for class K E[τK]: average service time for class K
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Simulation parameters
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Simulationa. no limit bandwidth
Offered Load
Channel
Utilization
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Simulationb. fixed quota
Offered Load
Channel
Utilization
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Simulationc. different data size (100 byte)
Offered Load
Throughp
ut
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Simulation d. different data size (150 byte)
Offered Load
Throughp
ut
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Simulatione. different data size ()
Offered Load
Throughp
ut
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Conclusions
The main target of WiMax is to replace the so called last mile.
It can advance a lot in the future.
Whether it can make it or not is still unable to answer.
But many companies have announced to support it, especially INTEL
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Reference
IEEE 802.16 Standards Performance Analysis of the IEEE 802.16
Wireless Metropolitan Area Network, (DFMA’05)
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END
END
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New Qos Architecture
Example– Backoff window size=B– Probability of choose a given slot=p=1/B– The probability of a given slot is not selected
Pns=(1-p)N
– System throughput is
Pth=Np(1-p)N-1
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Spec.
Provision of Qos– Based on the “Envelopes” – Parameters
ProvisionedQosParamSetA set of external QoS parameters provided to the MAC
AdmittedQosParamSetA set of QoS parameter for which the BS and possibly the SS are reserving resource
ActiveQosParamSetA set of QoS parameters that reflect the actual service being provided to the associated active service flows