Project
IEEE 802.20 Working Group on Mobile Broadband Wireless Access
<http://grouper.ieee.org/groups/802/20/>
Title
Proposed changes to the Traffic Modeling and Evaluation Criteria
Document (802.20 PD-09)
Date
Submitted
2007-1-15 (Jan 15, 2007)
Source(s):
Anna Tee
Samsung Telecommunications
America
Re:
802.20 Evaluation Criteria document
Abstract
This document proposes a traffic model mix that enables the evaluation of
system performance under a more realistic reverse link traffic load; and to
include the evaluation of system performance (PHY and MAC layers) at
high mobility in the Evaluation Criteria document.
Purpose
This document proposes updates to the Evaluation Criteria document, to
resolve some of the issues that have been discussed at the 802.20 Plenary
meeting on Wednesday, 15 Nov 2006.
Notice
Release
Patent
Policy
Voice: 1 (972) 761-7437
Email: atee@sta.samsung.com
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
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<http://standards.ieee.org/guides/opman/sect6.html#6.3> and in Understanding Patent
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1. Introduction
During the Working Group (WG) meeting in November 2006, several issues on the
Evaluation Criteria document (ECD) have been discussed. Possible improvements to the
traffic model mix, and the evaluation of system performance at high mobility, including
both physical and MAC layers, are suggested in this document for discussion and
consideration by the WG.
2. Traffic model
As discussed in contribution C802.20-06/18 [1] and C802.20-06/35 [2], the traffic model
mix that is specified in Section 4.4 of the approved version of the Evaluation Criteria
document [3], as shown in Table 1, has not included realistic reverse link data services
that are expected to be supported by 802.20 air interface technology.
With the intention of 802.20 technology to provide data services to mobile users, it is
important to ensure that typical reverse link data services such as file upload, e.g., photos
taken by a camera phone, attachments to email sent from a portable computing device,
are included in the evaluation. This type of data service can be modeled by FTP upload.
While full-buffer traffic model may have been used to evaluate the reverse link spectral
efficiency, the model does not represent a realistic, typical application scenario. For
example, TCP model is not included in a full-buffer traffic model.
Traffic
Category
Best Effort
Interactive
Streaming
Real-time
Interactive
Application
Percentage ( % )
FTP
Web browsing
Video streaming
VoIP
Gaming – (Optional)
30
30
30
10
-
Percentage with
Gaming
30
25
30
10
5
Table 1 [ECD-Table 7] Traffic mix: percentage of different Traffic Types
As a reference, the traffic models for the forward link and reverse link used for the
evaluation of 3GPP2 1xEV packet data technology, have been described in detail, in
Section 4.1 and 4.2 of the CDMA 2000 Evaluation Methodology document [4]
respectively. The three cases of reverse link service mix simulated include:
 100% data users
 100% voice users
 ~50% or ~80% voice users, with data traffic allocated to the rest of the users
Reverse-link data traffic is classified into two categories:
1. Web browsing requests, TCP ACKs to support forward-link traffic
2. FTP upload as a typical reverse-link specific data traffic
The traffic mix shown in Table 1 consists of reverse-link data traffic mainly in category
(1). Therefore, the evaluation of reverse link will be more realistic if the model for traffic
in category (2) is included in the mix.
a. Proposed changes to Traffic model mix
Although the traffic types or service mix in a mobile cellular environment varies
extensively depending on the demographics, geographical location and the time of the
day, the evaluation of system performance under appropriate traffic mix compositions
will be useful to determine the capability of the air interface technology in managing the
radio resources and adapting to the different requirements of each traffic type.
This will ensure that the technology does not perform well only for a certain type of
traffic requirement. For example, when some users are transmitting at high power, there
can be an increase in uplink interference which can affect the capacity. When the traffic
mix consists of small amount of uplink data transmitted at relatively low data rate only,
transmissions from these users do not subject to the higher level of uplink interference
that could be generated by users with more demanding data services, e.g., FTP upload.
The followings are possible options for an appropriate traffic model mix. If performance
data is available for more than one traffic model mix, the performance as the percentage
mix varies can become more predictable by interpolating between the available data
points.
Option 1: A traffic model mix specific for reverse link traffic
Add a subsection “4.4.1 Forward link traffic mix” to Section 4.4; refer to Table 7 of ECD
for the forward-link traffic mix.
Then add a subsection “4.4.2 Reverse link traffic mix” to include the following Table 2:
Traffic Category
Application
Best Effort (UL)
Interactive (DL)
Best Effort (DL)
Real-time (DL/UL)
Interactive (DL/UL)
FTP upload
Web browsing –UL Requests
FTP download –UL ACK
VoIP
Gaming – (Optional)
Percentage
(%)
30
10
10
50
-
Table 2 Proposed Reverse-link Traffic model mix
Percentage
with Gaming
30
5
10
50
5
Option 2: Traffic model mix that includes both forward link and reverse link specific
traffic
Use the traffic mix in Table 3 in place of the one in Table 1 to evaluate the performance:
Traffic Category
Application
Best Effort (DL)
Interactive (DL)
Streaming (DL)
Best Effort (UL)
Real-time (DL/UL)
Interactive (DL/UL)
FTP download –UL ACK
Web browsing –UL Requests
Video Streaming
FTP upload
VoIP
Gaming – (Optional)
Percentage
(%)
20
20
20
20
20
-
Percentage
with Gaming
20
15
20
20
20
5
Table 3 Traffic model mix for evaluation of both forward and reverse link simultaneously
b. Clarifications to the use of TCP models
To avoid ambiguity, and to further clarify the use of TCP model as an integral part of the
FTP model, the following modifications to Section 4.3.4 of the ECD is suggested. This
suggested change is consistent with the corresponding section (4.1.4.1) in the CDMA
2000 Evaluation methodology document [4].
4.3.4
FTP
…
The underlying transport protocol for FTP is TCP. The model of TCP connection
described in section 5.2.1 will be used to model the FTP traffic. The parameters for
the FTP application session are described in Error! Reference source not found..
…
3. Evaluation of system performance at high mobility
a. System-level performance evaluation for 250 km/h
In the approved version of ECD [3], the performance of 802.20 proposals at high
mobility, e.g., greater than 120 km/h, has been evaluated at the physical link level only.
While this evaluation provides performance data for the physical layer, performance at
the MAC layer has not been evaluated for users with high mobility.
For users at high mobility, transmission scheduling could be a challenge as the channel
quality indicator feedback may not be useful for these users. On the other hand, power
control does not function well for users at high mobility. Furthermore, handoff happens
more often for these users as they transverse across multiple cell sites within a short time.
The tolerance on handoff delay may thus be lower. Therefore, it is necessary to evaluate
the system-level performance for these high mobility users, especially because the 802.20
PAR and systems requirements document have stated that the support for mobility is up
to 250 km/h.
b. Proposed changes to the ECD
During the discussions in the November ’06 meeting, there were concerns regarding the
insignificance of the percentage of high mobility users in the urban and suburban channel
mixes. An alternative solution is to use a channel model mix that is representative of a
typical rural environment, such that the scenario with a significant percentage of high
mobility users can be evaluated.
The inclusion of this scenario will be consistent with Section 4.2.2 of the 802.20 systems
requirements document [5], which states that: ‘The system shall work in dense urban,
urban, suburban, rural, outdoor-indoor, pedestrian and vehicular environments…’.
i. Section 9.1 Channel Model Mix
Scenario 3: Rural cells –
User mobility mix: 120 km/h – 80%, 250 km/h – 20%
Other possible changes to this section may be necessary, for consistency with
updates on the 802.20 channel models document.
ii. Section 5.4: Mobility Modeling for Signaling Robustness Evaluation
Modify Table 13 as follows:-
Include 250 km/h to the cases for mobile speed V
-
Modify D0, Distance of starting point from A in paths 1 and 2 (same as
distance of ending point from B), to 35m
Rationale for the change of D0: Path loss calculation based on COST-231 Hata
urban propagation model requires a minimum distance of 35m from the BS [6]. In
the current version of ECD [3], the value for D0 is 30m, which will produce
inaccurate results when the path loss model is used as specified.
References
‘Proposed Traffic modeling Ad-hoc’, C802.20-06/18, March 3, 2006.
‘Presentation on Evaluation Criteria document’, C802.20-06/35, Nov. 15, 2006.
‘IEEE 802.20 Evaluation Criteria document (V1.0)’, IEEE 802.20-PD09, Sept., 2005.
‘CDMA 2000 Evaluation Methodology-Revision 0’, 3GPP2 C.R1002-0 Version 1.0,
December 10, 2004.
[5] ‘IEEE 802.20 Systems Requirements Document (V1.0)’, IEEE 802.20 PD-06r1, July 2004.
[6] ‘IEEE 802.20 Channel Models (V1.0)’, IEEE 802.20 PD-08, Sept, 2005.
[1]
[2]
[3]
[4]