2008-07-10
IEEE C802.16m-08/663r1
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Proposal for IEEE 802.16m Quick Paging Channel Design
Date
Submitted
2008-07-10
Source(s)
Shantidev Mohanty (shantidev.mohanty@intel.com)
Muthaiah Venkatachalam (Muthaiah.venkatachalam@intel.com) Shailender Timiri
(shailender.b.timiri@intel.com)
Sassan Ahmadi (Sassan.ahmadi@intel.com)
Intel Corporation
Call for Contributions on Project 802.16m System Description Document (SDD)
Re:
UMAC Power Management
Abstract
Proposal for IEEE 802.16m Quick Paging Channel Design
Purpose
Discussion and Approval
Notice
Release
Patent
Policy
This document does not represent the agreed views of the IEEE 802.16 Working Group or any
of its subgroups. It represents only the views of the participants listed in the “Source(s)” field
above. It is offered as a basis for discussion. It is not binding on the contributor(s), who
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Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and
<http://standards.ieee.org/board/pat>.
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2008-07-10
IEEE C802.16m-08/663r1
Proposal for IEEE 802.16m Quick Paging Channel Design
Shantidev Mohanty, Muthaiah Venkatachalam, Shailender Timiri, and Sassan Ahmadi
1
Introduction
This contribution proposes an idle mode paging channel design for IEEE 802.16m that
is more efficient than the channel design in the legacy IEEE 802.16e-2005 [1] in terms
of signaling overhead and terminal power consumption.
In the sections below, a brief description of the idle/sleep modes and the legacy IEEE
802.16e-2005 paging scheme is provided, followed by a description of the proposed
channel design for IEEE 802.16m. Finally, text is proposed for inclusion in the SDD.
2
Background
In IEEE 802.16 wireless networks, as in most wireless communication systems, mobile
stations (MS), can be in one of the following states:
State I: Receive or send traffic while in one or more active call sessions
State II: Do not receive or send traffic in any of the active call sessions
State III: Not engaged in any active call session
When an MS is either in state II or III, it can temporarily shut down all transmit and
receive activities with the network. Therefore, these states can be used as battery
conserving and wireless resource saving opportunities.
Wireless networks based on IEEE 802.16 use sleep mode and idle mode operation to
take advantage of State II and State III, respectively. In these modes, the base station
(BS) and MS use a pre-negotiated pattern of alternating inactive and active periods for
the MS. This conserves MS power while still maintaining a signaling connection - albeit
intermittently - with the BS.
During the active periods, the BS can communicate with the MS using ‘paging’
signaling, either to retain the MS in sleep/idle state or to force the MS to exit the
sleep/idle state. The MS however, can exit the sleep/idle mode at any time to initiate
communication with the BS.
This proposal deals with the BS ‘paging’ signaling to the MS in idle mode as well as BS
“Traffic Indication” to the MS in sleep mode in IEEE 802.16 based wireless networks.
3
Idle Mode Paging and Sleep mode traffic indication in IEEE 802.16e-2005
In IEEE 802.16 based wireless networks, a BS transmits a paging message
(MOB_PAG-ADV) for multiple MSs using multicast or broadcast connections. The
presence and location within the DL sub-frame of MOB_PAG-ADV is indicated by an IE
in the DL-MAP for the corresponding multicast/broadcast CID.
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IEEE C802.16m-08/663r1
This is further explained using Figure 1, which shows a downlink IEEE 802.16e frame
containing a MOB_PAG-ADV message. The downlink frame shown in Figure 1
corresponds to an IEEE 802.16e based wireless system employing time division duplex
(TDD) mode of operation. The frame starts with a preamble for synchronization followed
by a Frame Control Header (FCH), which provides frame configuration information. FCH
is followed by downlink MAP (DL-MAP) and uplink MAP (UL-MAP) messages that
contain sub-channel allocation and other control information for downlink (DL) and
uplink (UL) sub-frames, respectively. The remaining part of the DL frame contains
control and data traffic for different users. The PIE is one of the IEs that are present in
the DL-MAP. IEEE 802.16e specifies that the PIE contains the idle mode multicast CID
or broadcast CID along with the location of the MOB-PAG-ADV message that is
identified by this CID.
FCH
P
r
e
a
m
b
l
e
PIE
SIE
DL
M
A
P
MOB-PAG-ADV
MOB_TRF-IND
UL
M
A
P
Figure 1: IEEE 802.16 DL frame showing idle and sleep mode control message transmission.
An idle mode MS performs the following operations in its paging available interval to
look for any MOB_PAG-ADV message addressed to it.
Step 1: It synchronizes with the serving BS using the preamble.
Step 2: It decodes the FCH to learn about the frame configuration information.
Step 3: It decodes the DL MAP and looks for the presence of a PIE. If the MS does not
find the PIE it stops any further processing of the current DL frame.
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IEEE C802.16m-08/663r1
Step 4: If the PIE is present, then it reads the part of the DL frame containing the
MOB_PAG-ADV message and checks if it is addressed in the message. If addressed,
the MS returns to normal mode of operation using procedures defined in the
specifications, else it remains in idle mode.
Similarly, in sleep mode the MS can receive traffic indication (akin to paging in idle
mode) message, MOB_TRF-IND, and it goes through the same set of steps as above to
decode the traffic indication message.
In this proposal we minimize the overhead and processing required for the MS to get to
the paging and traffic indication messages.
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Proposed Quick Paging Channel for IEEE 802.16m
Super-Frame 20 ms
Super Frame K
Super-Frame
Header
FCH
CCP
Super Frame K+1
Preamble
Common Control
and Signaling Channel
FCH
Frame 5 ms
FCH
FCH
Sector ID
Frame #
.
.
Header
CCSCH
FCH
Information not
related to resource
allocation
s
Information related
to resource
allocation
s
PI (1) SI (1)
Other
Indicators
MOB -PAG -ADV (if PI)
MOB TRF IND (if SI)
DL MAP
Bit map to indicate
the presence/absence of
broadcast control messages
in
CCSCH
UL MAP
Figure 2. Proposed Idle and Sleep Mode Paging Channel Design
The proposed method retains the legacy IEEE 802.16-2005 paging method using 2stage signaling starting with a paging indicator (PI) and sleep indicator (SI) followed by
the paging message (MOB_PAG-ADV) and traffic indication message (MOB_TRF_IND)
respectively. However, the proposal uses a paging channel for signaling instead of
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IEEE C802.16m-08/663r1
MAP-based messaging. The main idea is to designate resources for paging control
channels and/or fields within a control channel in the DL-frame where the fixed-length
paging indicator and variable-length paging message appear. MSs can then obtain their
paging signaling without having to decode the DL-MAP.
For illustration purposes, the proposal is presented in Error! Reference source not
found. as an extension of the super-frame header design proposed in [3]. However, it
can be adapted for other schemes as well. It shows the super-frame structure, with 4
frames and an assumed 5ms preamble. The first frame of the superframe contains the
SFH and all frames begin with a FCH (Frame Control Header), which has similar
functionality as in the legacy IEEE 802.16e-2005 system. In the SFH frame, the FCH is
followed - in order - by thControl and Signaling Channel). In a non-SFH frame, the FCH
is followed by the CCSCH. The preamble periodicity and location of the SFH are strictly
for illustration purposes and inconsequential to this proposal.
As shown in Error! Reference source not found., the Paging Indicator (PI) and sleep
indicator (SI) appear at a fixed location within a bitmap field in the CCSCH. The location
of the CCSCH is indicated by the FCH (Frame Control Header) in a non-SFH frame
and by the CCP (Common Control Prefix) in a SFH frame.
A 16m idle mode MS performs the following operations in its paging available interval to
look for any MOB_PAG-ADV message addressed to it.
Step 1: It synchronizes with the serving BS using the preamble.
Step 2: It decodes the FCH to learn about the frame configuration information.
Step 3: If this is an SFH frame (first frame of a super-frame), it decodes the CCP to
obtain the location of the CCSCH
Step 4: It decodes the CCSCH, checks the paging indicator (this is apart from other
checking such as for the broadcast update indicators and BSID for location updates). If
the paging indicator is not set, the MS stops any further processing of the current DL
frame and returns to the inactive state.
Step 5: If the paging indicator is set, then the MS reads the next field in the CCSCH
which contains the MOB_PAG-ADV message and checks if the MS is addressed in the
message. If addressed, the MS returns to normal mode of operation using procedures
defined in the specifications, otherwise it remains in idle mode.
Similar operation is performed by a 16m sleep mode MS to obtain and decode the traffic
indication message.
5
Advantages of the proposed approach
The proposed approach for quick paging and traffic indication has the following
advantages:
a) Lesser overhead on the control channel: the presence of paging and traffic
indication messages are indicated by one bit each as opposed to an entire MAP
IE. Also the MOB_PAG-ADV and MOB_TRF-IND messages do not need a
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IEEE C802.16m-08/663r1
separate GMH since they are part of the L1/L2 control and not sent as MAC
management messages
b) Better power efficiency for the low power MS: since the PI and SI are present at a
fixed location, the low power MS can basically check these known locations to
see if the PI or SI bits are set. If the bits are not set, then the low power MS can
go back to unavailability right away and save battery power.
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Proposed Text for SDD
Insert the following text into Idle Mode Paging Design sub-clause (i.e. Chapter xx
in [2]):
------------------------------- Text Start --------------------------------------------------6.1.1.1.1.1.1.1 x. x.x.x Idle Mode Paging Channel Design
The idle mode paging signaling in 16m consists of a paging indicator(PI) and a paging
message, MOB_PAG-ADV. In IEEE 802.16m, PI and MOB_PAG-ADV are sent on a paging
channel in the downlink frames in pre-defined, known locations. These locations can be
accessed and decoded using the frame structure information that is present at the beginning of
every frame.
------------------------------- Text End --------------------------------------------------Insert the following text into Sleep Mode Traffic indication Design sub-clause (i.e.
Chapter xx in [2]):
------------------------------- Text Start --------------------------------------------------6.1.1.1.1.1.1.2 x. x.x.x Sleep Mode Traffic indication Channel Design
The sleep mode traffic indication signaling in 16m consists of a sleep indicator(SI) and a traffic
indication message, MOB_TRF-IND. In IEEE 802.16m, SI and MOB_TRF-IND are sent on a
paging channel in the downlink frames in pre-defined, known locations. These locations can be
accessed and decoded using the frame structure information that is present at the beginning of
every frame.
------------------------------- Text End --------------------------------------------------7
References
[1] IEEE Std. 802.16e-2005, IEEE Standard for Local and metropolitan area networks,
Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems,
Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and
Mobile Operation in Licensed Bands, and P802.16Rev2/D3 (February 2008).
[2] IEEE 802.16m-08/003r2, “The Draft IEEE 802.16m System Description Document”
[3] IEEE C80216m-08_489, “Proposal for IEEE 802.16m Super-frame Header Design”
6