IEEE C802.16m-08/1097r2
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Dynamic RRM Support for Enhanced Multicast Broadcast Services
Date
Submitted
2008-09-13
Source(s)
Ray-Guang Cheng and Feng-Ming Yang
National Taiwan University of Science
and Technology
Voice:
E-mail:
+886-2-27376371
crg@ieee.org
*<http://standards.ieee.org/faqs/affiliationFAQ.html>
Re:
PHY & MAC aspects of enhanced MBS; in response to the TGm Call for Contributions and
Comments 802.16m-08/033 for Session 57
Abstract
This contribution proposes functions required to support dynamic RRM for E-MBS
Purpose
Discussion and Approval
Notice
Release
Patent
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Dynamic RRM Support for Enhanced Multicast Broadcast Services
Ray-Guang Cheng and Feng-Ming Yang
National Taiwan University of Science and Technology
1 Introduction
This contribution proposes a NACK-based channel quality feedback mechanism that is suitable for both
awake/sleep mode or in idle mode SSs. SSs shall send a MBS service flow specific CDMA code at a common
random access channel to indicate its NACK if they do not satisfy a given feedback condition specified. The
common random access channel can also be shared by multiple MBS service flows that use different CDMA
codes. Therefore, the uplink signaling overhead can be minimized.
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IEEE C802.16m-08/1097r2
2 Description of the Proposal
In 802.16Rev2, MBS service is offered in the downlink only and the MBS service flows should be
transmitted and maintained for SS either in awake/sleep mode or in idle mode. It has been shown in the
literature that the number of synchronized transmitting cells in an MBS zone, the cell size, and the users’
location distribution are factors that may affect the selection of MCS state. Unfortunately, the network cannot
dynamically allocate the radio resource (e.g., transmission power control, MCS state selection, HARQ
parameter setting) for BSs belonging to the same MBS zone due to the lack of a feedback mechanism. In order
to enhance the spectral efficiency of E-MBS, a feedback mechanism with low signaling overhead is required for
both awake/sleep and idle SSs that receiving the same MBS services to report their service qualities.
The selections of proper feedback channel and right feedback information are two main issues that
should be considered while designing the feedback mechanism. The feedback channel should be able to
accommodate SSs either in awake/sleep mode or in the idle mode. The feedback information should be detail
enough for SSs to indicate their received quality and also be simple enough to minimize the uplink signaling
overhead.
Possible choices for the feedback channel include a random access channel, a shared uplink control channel,
or a dedicate uplink control channel. For SSs in idle mode, they can only use random access channel to
communicate with the BS. For SSs in awake/sleep mode, they can use random access channel, shared uplink
control channel, or dedicate uplink control channel to communicate with the BS. A common random access
channel that is shared by SSs in both awake/sleep mode and idle mode could be used to minimize the
number of feedback channel required for each E-MBS service flow.
Potential options for the feedback information include ACK/NACK and CQI. The ACK/NACK may be
used to indicate that the satisfaction/dissatisfaction of SS’ QoS requirement (e.g., SNR, packet error rate (PER),
peak signal-to-noise ratio (PSNR), etc.). The CQI can be used to carry the exact channel quality (e.g., Physical
CINR, Effective CINR feedback, MOMO-related feedback, etc.) experienced by the SS. In MBS, the radio
resource is normally adjusted according to poor-quality SSs but not all SSs. Hence, it is preferred to let
dissatisfaction SSs use a simple NACK message to report its QoS status. In MBS, the network cares more about
the received quality of the reported SS and does not interest in its user identity. Therefore, a CDMA code,
instead of a user-specific message, can be used by SSs receiving the same E-MBS service flow to indicate
their NACKs to minimize signaling overhead.
In this contribution, we propose to
- Reserve a group of CDMA ranging code for E-MBS, where each E-MBS-specific CDMA code is
assigned to one E-MBS service flow or is shared by multiple E-MBS service flows;
- Allocate a common random access channel for both awake/sleep mode and idle mode SSs that
receiving the same E-MBS service flows to report their channel quality. The allocation of the
common random access channel can be periodic or event-triggered, which depends on a feedback
condition specified by the network.
- SS, who is not satisfied with a given feedback condition (e.g., SNR, PER, PSNR), shall indicate a
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IEEE C802.16m-08/1097r2
NACK by sending its CDMA code through the allocated common random access channel.
Note that, the network has to announce the feedback condition and its associated channel allocation in a MBSspecific control channel (or a general broadcasting channel) that can be received by both awake/sleep mode and
idle mode SSs. The same common random access channel can be shared by multiple E-MBS service flows that
use different CDMA codes and thus, minimize the signaling overhead for channel quality feedback.
3 Proposed Text for the System Description Document (SDD)
---------------------------------------------Start of the text-----------------------------------------------15 Support for Enhanced Multicast Broadcast Service
[Add the following text to section 15.]
15.x E-MBS Feedback
E-MBS may support feedback mechanism for certain E-MBS services to enhance their bandwidth efficiency.
The feedback mechanism can be enabled based on individual E-MBS service flow. In case that E-MBS
feedback is enabled, both awake/sleep and idle SSs that receiving the same MBS service should use one of the
following feedback mechanisms selected by the network to report E-MBS related information.
15.x.1 NACK-based Feedback
In this method, a NACK-based feedback is supported. The network may reserve a group of CDMA ranging
code for E-MBS feedback. Each E-MBS-specific CDMA code may either be reserved for an E-MBS service
flow or be shared by multiple E-MBS service flows. The network shall specify a feedback condition (e.g., SNR,
PER, PSNR, etc.) and allocate a random-access-based common feedback channel for both awake/sleep mode
and idle mode SSs that receive the same E-MBS service flow to report their status. SS, who is not satisfied with
the feedback condition, shall indicate a NACK by sending its E-MBS-specific CDMA code through the
allocated common feedback channel. The feedback condition and the allocation of feedback channel can be set
in a periodic or event-triggered manner. The feedback condition and the allocation of feedback channel shall be
announced in a MBS-specific control channel (or a general broadcasting channel) and be received by all SSs in
either awake/sleep mode or idle mode. Note that, the same random access channel can be shared by multiple EMBS service flows which are assigned by different CDMA codes.
---------------------------------------------End of the text------------------------------------------------
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