2005-01-17
Project
IEEE C802.20-05/07
IEEE 802.20 Working Group on Mobile Broadband Wireless Access
<http://grouper.ieee.org/groups/802/20/>
Title
Proposal of a Procedure for the System-Level Simulator Calibration
Date
Submitted
2004-1-17
Source(s)
David Huo
Lucent Technologies
Voice : 973-428-7787
Email: dhuo@lucent.com
67 Whippany Rd, Rm2A-384
Whippany, NJ 07981
Re:
Contribution to IEEE 802.20 (Assignment from Conference Call 12/21/2004)
Abstract
This contribution proposes a procedure for the calibration of the system-level simulator.
Purpose
For discussion & adoption into 802.20 evaluation criteria document.
Notice
Release
Patent
Policy
This document has been prepared to assist the IEEE 802.20 Working Group. 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.
The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this
contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright
in the IEEE’s name any IEEE Standards publication even though it may include portions of this
contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting
IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be
made public by IEEE 802.20.
The contributor is familiar with IEEE patent policy, as outlined in Section 6.3 of the IEEE-SA Standards
Board Operations Manual <http://standards.ieee.org/guides/opman/sect6.html#6.3> and in Understanding
Patent Issues During IEEE Standards Development <http://standards.ieee.org/board/pat/guide.html>.
2005-01-17
IEEE C802.20-05/07
Introduction
In the latest version of the IEEE 802.20 Evaluation Criteria Document [1], the section on
calibration is still open. Document [3] has made a proposal to the possible approach for
the simulator calibration. This contribution proposes a procedure to achieve the objective
of the calibration of system level simulator for the evaluation of MBWA.
The purpose of the simulator calibration is to assure that all the participating parties are
using the same mathematical formulation and the same parameters in the their respective
simulator to simulate the given scenario of the propagation environment. In other words,
the calibration helps to unify the specification for the various simulation codes to be
developed to achieve the same simulation task. Without this procedure even the simplest
simulation task can have generate different results from different simulators. For
instance, in one simulator a given mobile at a given location may experience a different
distribution of the SNR than all others just because of a bug in one of the simulator code.
Given the complexity of the simulation task, the calibration must be systematic,
incremental and step-wise, in order to achieve the objective. In the context of WBMA,
we are dealing with multiple interacting stochastic processes, all of which are simulated
by Monte Carlo method. A calibration must be designed such that the significant errors or
deviations of the parameters can be detected by means of comparison of independently
developed simulation programs. For this, we propose the following procedure for
section 6.1.2 “Phase 1 Calibration".
Proposal -----------------------------------------------------------------------------------------------6.1.2 Phase 1 Calibration
6.1.2.1 Step 1: Deterministic Calibration
The purpose of deterministic calibration is to assure that the basic configuration and
layout of the simulation environment is coded in accordance with the evaluation criteria.
The configuration of the simulation scenario is characterized by the following
parameters:
(Assumption 1)




Uniformly distributed users in 19 3-sectored cells (assuming the wrap-around
model specified in Appendix A)
Inter-cell distance: 2.5 km
Path loss model as specified in the channel model document for suburban macro,
urban micro cells etc.
C/I is measured as the received signal power divided by the noise plus
interference power.
2005-01-17


IEEE C802.20-05/07
Mobiles are dropped in deterministic location in each sector. For instance, 3
mobiles in each sector, located at the tow corners and in the middle of the sector
determined by the middle pointer of the sector triangle
A single antenna for BS and for MS, respectively.
As results, the quantity C/I of each mobiles is plotted in a spread sheet, for which a
common definition of numbering scheme need be set. Such a number scheme could be,
for example: a=index of the sector (0,1,2…,57) , b=index for location within the sector
(0,1,2 in counter clock-wise, in case of 3 mobiles per sector)
This calibration shall be performed for both uplink and downlink.
6.1.2.2. Step 2: Monte Carlo Simulation I
After the deterministic calibration succeeds, the second step is to perform simple
stochastic calibration. The random parameters will be added incrementally into the
parameters given in Assumption 1:
(Assumption 2):










Maximum C/I = 30 dB.
No handoff
No power control
No admission control
Full-buffer traffic model
Fast fading according to the channel models specified in the evaluation document
Lognormal shadowing standard deviation = 8 dB. The actual fading value is
generated at the beginning of the simulation and remain constant during the
simulation.
10 users/sector at the fixed locations
Simulation duration : 10 seconds
Time interval for fast fading channel update & (C/I) data collection: 1 ms for MS
speed ~3 km/h, 40 ms for MS speed ~120 km/h.
As output, the cumulative distribution (CDF) plots of user C/I, for both Downlink and
Uplink, shall be provided for comparison.
6.1.2.3 Step 3: Monte Carlo Simulation II
More random variables can be added to the simulator:
(Assumption 3)


Users are dropped independently in each sector following a uniform distribution,
where area within 35m of radius around the base station is prohibited.
Handoff is allowed, but no soft handoff
2005-01-17

IEEE C802.20-05/07
Each user selects the sector with the best downlink long-term channel gain (i.e.,
excluding short-term fading) as the serving sector.
As output results, the following statistics shall be provided for comparison:
1. Cumulative distribution (CDF) plots of received C/I, evaluated as time average
where the time average is performed over a fixed time window (TBD)
2. CDF plots with user’s distance from the serving sector as parameter. For the
evaluation of this CDF, each sector is divided into M bins in radial direction.
Hence totally M curves will be evaluated and plotted.
3. CDF of C/I for given deterministic locations, say 3 selected location from the
3x3x19=171 possible locations.
4. All plots are evaluated for both uplink and downlink
I oc
, where Ior is the
I or
average received power from intra-sector users and Ioc is the average received
power from users outside the sector. The contribution from thermal noise is
excluded from the calculation. All users are given the same system resources on
the uplink. The output is the CDF of this quantity.
5. Relative uplink inter-sector over intra-sector received power
6.1.2 .4 Step 4: Monte Carlo Simulation III
(Assumption 4)
Under the assumption that power control will be an indispensable component, there is a
need to calibrate the simulation with power control, in which a common power control
scheme and power control parameters need be specified.
In addition to full-buffer traffic model, the simulator shall also be calibrated using the
non-trivial traffic models. For given C/I threshold and without an admission control, the
output of this simulation is the CDF of the packet size and the inter-arrival time.
In addition, simulation with a common mobility model will be performed and results
evaluated.
6.1.2. 5 Further Calibration
Depending on the process of technology evaluation and selection, further calibration with
more realistic assumptions may be performed during the evaluation process, e.g., by
using a common set of link-level performance curves [2].
2005-01-17
IEEE C802.20-05/07
Recommendation
Noting that the calibration procedure is not targeted at evaluating technical proposal,
rather to calibrate the tools to be used for the evaluation, the goal of the calibration is set
such that all participating simulators deliver results within an acceptable deviation. I
recommend the adoption of the proposed procedure into the evaluation document.
References
1. “IEEE 802.20 Evaluation Criteria Document Version 11r2”, Oct 24, 2004.
2. 3GPP2/TSG-C.R1002, “1xEV-DV Evaluation Methodology (V14)”, June 2003.
3. “System-level calibration method for IEEE 802.20 technology evaluation”
C802.20-04/83r1