2007-09-12 IEEE C802.20-07/37
Project / IEEE 802.20 Working Group on Mobile Broadband Wireless Accesshttp://grouper.ieee.org/groups/802/20/
Title / IMT Advanced Evaluation Criteria – Proposed Submission
Date Submitted / 2007-09-12
Source(s) / Jim Tomcik and Ayman Naguib
Qualcomm, Inc.
Radhakrishna Canchi
Kyocera Corporation
Re: / MBWA Call for Contributions
Abstract / Proposed updates and additional changes to current 802.20 Evaluation Criteria and Channel Models document for submission to 802.18 for IMT Advanced
Purpose / Provide inputs to 802.18 for IMT Advanced Evaluation Criteria
Notice / 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.
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The 802.18 TAG will start work on further requirements for IMT-Advanced including any information that is deemed relevant on the radio interface evaluation criteria as part of that effort. This work will start at the September Interim.
At the March 2007 Plenary, the 802.20 Working Group approved submitting to 802.18 for future use in IMT Advanced submissions the Channel Models document, PD-08r1. The document was submitted as an approach to modeling both SISO and MIMO channels, and proposes a methodology to relate the two types of channel models.
This input contribution provides a brief summary to a number of changes that need to be addressed in the current 802.20 evaluation methodology document in order to prepare it for possible submission to the ITU regarding IMT-Advanced evaluation. There are a number of areas in the document that need some substantial improvements. Here we mention some specific areas for improvement. However, other additions/improvement may be necessary. An update to the previously submitted Channel Models document is also discussed. It is also proposed that 802.20 re-resubmit the Channel Models document to 802.18 as a number of months have passed since the previous submission.
· Link to System Interface (Section 7 of 802.20-PD-09): This is perhaps the most deficient section in the document. The document does not actually specify any methodology for mapping between the link sims and systems sims. All what is stated is that whatever mapping is used, the proponent should provide enough justification for this mapping. While this may seem to provide flexibility, this has several drawbacks. First, there is no common mapping methodology and hence it will be difficult to compare different systems. In addition, while the document requires each proponent to justify whatever mapping is used, there is no clear way of judging whether that mapping/justification is acceptable or not. We proposed to expand this section to discuss mapping techniques that are known in the literature with specific focus on the “effective SNR approach”. More specifically we need to:
o Describe the effective SNR approach for link to system mapping for SISO and MIMO cases
o How HARQ and link adaptation are modeled.
o How the interference is modeled.
· Handover Evaluation and Modeling (Section 5.4 of the document): we need to define specific for single terminal and multiple terminal cases. We need to consider addition Handover performance metrics:
o Radio Layer Latency
o Network Entry time
o Connection setup time
o Service disruption time
o Data loss
o HOV failure rate
o Power saving and management
· Traffic Models: The evaluation criteria document already lists a number of different traffic models. A review for these models is warranted and specifically for the real time video streaming. We also need to add a traffic model for video telephony. Video telephony is one of the multimedia applications that any IMT-2000 compliant system is expected to support and it must be expected that it will also be one of the service requirements for IMT-Advanced. We also need to revise the current traffic mix scenarios.
· Performance Metrics: The current evaluation methodology document list three performance metrics that need to be reported. These are: (1) the user data rate CDF for a fixed base station separation and fixed load, (2) aggregate throughput vs. base station separation at minimum service levels, and (3) spectral efficiency. For the purpose of IMT-Advanced evaluation, we need to update this section to include a number of other performance metrics that measure the system performance at different system layers. For example, at the physical layer some other performance metrics that need to be included are (1) per user average data throughput, (2) sector data throughput, (3) cell edge user throughput, (4) average packet call throughput, (5) performance metrics for delay sensitive applications. The previous list serves only as an example of the additional performance metrics that need to be addressed and/or added.
· Channel Models: The evaluation criteria document makes reference to the channel modeling document and states that these models are to be used in these simulations. While the channel modeling document is in a very good shape, a number of issues here need to be addressed. First, In addition to SISO channels, the channel modeling document focuses on the correlation matrix approach for simulation MIMO channels and describes several options for generating the correlation matrices. The SCM channel model is listed in the appendix and is only to be used to generate the correlation matrices. The issue of relating the MIMO channel models to the baseline ITU SISO channel models is being discussed within WP8F and other correlation based approaches are being considered right now which are based on the European WINNER project models. We suggest that we update the channel modeling document as follows: (1) include other deployment channel models that came out of the WINNER project studies, e.g. Bad Urban Microcell, Hot spot models, etc. (2) include the SCM model as an alternative for generating MIMO Channels, (3) include the clustered taped delay model for generating MIMO channel (This model is similar to the correlation matrix approach already described in our channel modeling document. However it provides the flexibility of specifying an angle spread, a mean angle of arrival for each tap). The second issue that need to be address with the channel modeling as far as the evaluation methodology document is concerned is whether to have the channel modeling document as a separate document or embedded it into the evaluation methodology document. Note that IMT-2000 M1225, which serves as the evaluation methodology document for IMT-2000 explicitly include the channel models and the corresponding IMT-advanced document is expected to have a similar structure.