Transcript 11/99 doc.: IEEE 802.15-99/117 IEEE P802.15 Working Group for Wireless Personal Area Networks MAC Performance Evaluation Process in a Coexistence Environment Nada Golmie NIST Submission Slide 1 Nada Golmie, NIST.

11/99
doc.: IEEE 802.15-99/117
IEEE P802.15 Working Group for
Wireless Personal Area Networks
MAC Performance Evaluation
Process in a Coexistence Environment
Nada Golmie
NIST
Submission
Slide 1
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
MAC Coexistence Model
• Different performance levels will lead to
different levels of coexistence:
– Coexistence could mean an “acceptable”
performance level to be quantified.
• At the MAC layer coexistence translates into a
performance measure:
– What is the impact of interfering devices all
sharing the 2.45 GHz ISM band on the MAC
performance?
• How to evaluate and quantify WPAN MAC
performance?
Submission
Slide 2
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
Objectives
• The main goal of this contribution is to
propose a methodology for conducting a
performance evaluation of the WPAN MAC in
presence of other wireless devices sharing
the same air space.
• The motivation is to agree on an evaluation
process so that simulation/ experimental/
analysis results can be conducted
independently by different parties and
presented to the IEEE 802.15 SG.
Submission
Slide 3
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
MAC Performance Evaluation Set Up
Traffic Models
802.11 MAC
Traffic Models
Identify MAC
Specifications
BT MAC
PHY Layer
Assumptions
PHY Layer
Assumptions
Make
assumptions
Network Topology
on the PHY
layer
in a Coexistence Environment
(interference/
propagation
Traffic Models
Traffic Models models) and
traffic models
BT MAC
802.11 MAC
PHY Layer
Assumptions
Submission
Measure performance
at the MAC layer
Slide 4
PHY Layer
Assumptions
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
MAC Coexistence Evaluation Process
The evaluation process of a given MAC layer
protocol in a shared environment consists of:
– Usage scenarios
• User situations
• Applications
– Parameters
•
•
•
•
Traffic generation models
Network topology
PHY layer assumptions
MAC layer parameters
– Performance metrics
Submission
Slide 5
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
Bluetooth User Situations *
•
•
•
•
•
•
•
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Internet Bridge
Interactive Conference
Cordless Desktop
Headset/Portable speaker phone
Briefcase Trick
Forbidden Message
Automatic Synchronizer
Instant Postcard
* www.bluetooth.com
Submission
Slide 6
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
IEEE 802.11 User Situations
• The Basic Service Set (BSS) consists of:
– Access Points (AP)
– Wireless Stations (STA)
• Need to consider *:
– STAs density per area
– AP density per area
– Number of STAs per AP
* refer to IEEE 802.15-99/073r0
Submission
Slide 7
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
Coexistence User Situations
• Office space situations
– desktop, interactive conference,
– automatic synchronizer, headset
• Dynamic situations (anywhere else)
– internet bridge
– instant postcard
– forbidden message
Submission
Slide 8
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
Applications
•
•
•
•
•
•
Telephony
Email
Web Browsing
File Transfer
Paging
Video Conferencing
Submission
Slide 9
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
Traffic Generation Models
• Traffic models that describe the distribution
of the message size and interarrival time are
derived from the application set considered.
• Many traffic models exist in the literature for
voice, data (FTP, HTTP), video traffic.
1
X1
Probability
0.9
X3
X2
0.8
0.7
0.6
0.6
0.5
0.25
0.4
0.3
Arrival Axis
T1
T2
T3
0.06
0.04
0.2
0.03
0.02
0.1
0
Mean interarrival time = 1/
Illustrations from IEEE 802.14/96-083r2
Submission
64
Slide 10
128
256
512
Message Size (Bytes)
1024
1518
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
Network Topology
• Number of devices in a piconet
• Distance among devices in a piconet
• Number of piconets
Submission
Slide 11
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
Physical Layer Parameters and Assumptions
• Frequency hopping
• Interference model
– Power level
– BER
– Overlapping probability
• Propagation model
– Path loss
Submission
Slide 12
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
MAC Layer Parameters
•
•
•
•
•
Contention slot allocation
Slot scheduling algorithm
Timers: Flush, ACK
Packet size/compression
Backoff algorithm:
– contention window size (max, min)
Submission
Slide 13
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
Performance metrics
• Access delay (mean, variance, PDF):
– time to transmit a message
• Collisions per slot
– average number of collisions per slot
• Offered Load
– actual traffic presented to the network for
transmission in bits/s
• Throughput
– Measure in bits/s of the successful traffic
transmitted excluding MAC and PHY overhead.
Submission
Slide 14
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
Summary
• Propose a methodology for MAC coexistence
model evaluation.
• List major components and provide examples
for parameters, user situations, and
performance metrics.
• Details within each components are work in
progress
Submission
Slide 15
Nada Golmie, NIST
11/99
doc.: IEEE 802.15-99/117
Next Step
• Let’s start the debate
• Agreement on this evaluation process
• Solicit input to complete
– Usage situations
– Network Topology
– Parameters
DATA
MAC
PHY
RF
Submission
Slide 16
Nada Golmie, NIST