IEEE 802.16m-09/0640
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Proposed Text for Sleep Mode Operation Section in the IEEE 802.16m Amendment
Date
Submitted
2009-03-02
Source(s)
Yeongmoon Son, Jung Je Son, Rakesh Taori
ym1004.son@samsung.com
Samsung Electronics
jchow@zteusa.com
Jerry Chow, Mary Chion
ZTE
chkoo@huawei.com
Changhoi Koo
Huawei
Re
“802.16m AWD”:
IEEE 802.16m-09/0012, “Call for Contributions on Project 802.16m Amendment Working
Document (AWD) Content”.
Target topic: “10.5 Power Management (Sleep, Idle)”.
Abstract
The contribution proposes the text of Sleep Mode section to be included in the 802.16m
amendment.
Purpose
To be discussed and adopted by TGm for the 802.16m amendment.
Notice
Release
Patent
Policy
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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 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 802.16.
The contributor is familiar with the IEEE-SA Patent Policy and Procedures:
<http://standards.ieee.org/guides/bylaws/sect6-7.html#6> and
<http://standards.ieee.org/guides/opman/sect6.html#6.3>.
Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and
<http://standards.ieee.org/board/pat>.
Proposed Text of Sleep Mode Operation Section
for the IEEE 802.16m Amendment
1. Introduction
This contribution proposes amendment text to describe the 802.16m sleep mode operation and is intended as a
section to be included in the 802.16m amendment. The proposed text is developed so that it can be readily
combined with IEEE P802.16 Rev2/D9 [1], it is compliant to the 802.16m SRD [2] and the 802.16m SDD [4],
and it follows the style and format guidelines in [3]. Current SDD [4] is used as a basis for the text development.
In Section 2, the main changes w.r.t. the current SDD are outlined, which is aimed at helping the understanding
of the amendment text.
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IEEE 802.16m-09/0640
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2. The summary of the proposed changes
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The text proposed in this contribution includes the followings:
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
Introduction
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
Sleep Mode Entry by explicit signaling
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
Sleep Mode Operation
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o
Sleep Cycle Operation to fix or exponentially double itself based on negotiated parameters between AMS and ABS
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Sleep Window & Listening Window operation
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o Traffic Indication by Broadcast Traffic Indication message
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o Listening Window Extension by implicit signaling
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o Sleep Mode Change by explicit signaling
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
Sleep Mode Exit by explicit signaling or other events (e.g. HO or DSA transaction)
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The text proposed in this contribution is based on the subclause 10.5.1 of the IEEE 802.16m SDD [4]. Additions
and modifications are outlined below:

Subclause 10.5.1.2 of [4] describes Sleep Mode entry. We described the missing details (e.g. exactly when to enter Sleep
Mode), and handling of the abnormal conditions (e.g. how to handle “concurrent” Sleep Mode entry transactions from the
AMS and ABS).
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Sleep Mode Entry

Sleep Mode Operation
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Subclause 10.5.1.3.1 of [4] describes Sleep Cycle may change implicitly. But the implicit Sleep Cycle change need
more detail description. Therefore, we added the Sleep Cycle which can be exponentially twice previous Sleep
Cycle based on traffic existence during Listening Window, subclause 6.3.20.2 of [1].
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Processing of Traffic Indication message
Subclause 10.5.1.3.3.1 of [4] describes traffic indication operation. Here, we describe more detailed behavior of the
AMS and ABS related to the handling traffic indication message.
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Sleep pattern change operation
In [1], an AMS or an ABS can change the characteristic of Sleep Mode while the AMS in Sleep Mode. We added the
detail operation about Sleep Mode change by explicit signaling. In addition, we clarified the behavior that AMS and
ABS shall perform upon detection of concurrent Sleep Mode change request transaction between AMS and ABS.
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Sleep Window and Listening Window operation in detail
Subclause 10.5.1.3.2 and 10.5.1.3.3 of [4] provides a high level guideline of what an AMS or an ABS does during
Sleep Window and Listening Window respectively. Here, we describe detailed operations during Sleep Window and
Listening Window.
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Sleep Cycle operation based on Rev 2[subclause 6.3.20.2 of [1]]

Sleep Mode exit
Subclause 10.5.1.3.4 of [4] describes the Sleep Mode exit. We described more detail Sleep Mode exit by explicit
signaling and other events (e.g. DSA transaction and HO). We also added the behavior that AMS and ABS shall
perform upon detection of simultaneous Sleep Mode change request between AMS and ABS.
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IEEE 802.16m-09/0640
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3. References
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[1] IEEE P802.16 Rev2 / D9, “Draft IEEE Standard for Local and Metropolitan Area Networks: Air Interface
for Broadband Wireless Access,” Jan. 2009.
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[2] IEEE 802.16m-07/002r7, “802.16m System Requirements”
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[3] IEEE C802.16m-08/043, “Style guide for writing the IEEE 802.16m amendment”
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[4] IEEE 802.16m-08/003r7, “The Draft IEEE 802.16m System Description Document”
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IEEE 802.16m-09/0640
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4. Text proposal for inclusion in the 802.16m amendment working document
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-------------------------------
Text Start
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15. Advanced Air Interface
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15.2. MAC layer
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[Insert a new section 15.2.1:]
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15.2.1.
Sleep Mode
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15.2.1.1.
Introduction
---------------------------------------------------
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Sleep Mode is a mode in which an AMS conducts pre-negotiated periods of absence from the serving ABS air interface.
Per AMS, a single power saving class is managed in order to handle all the active connections of the AMS. Sleep Mode
may be activated when an AMS is in the connected state. When Sleep Mode is active, the AMS is provided with a series
of alternating Listening Windows and Sleep Windows. The Listening Window is the time in which AMS is available to
receive and send signaling and/or data from and to the ABS. The start of the Listening Window is aligned at the frame
boundary. During the Listening Window, the AMS is expected to receive and process DL transmissions in the same way
as in Active Mode.
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The Sleep Window is the time in which the AMS is unavailable for DL communication with the serving ABS. Therefore,
during the Sleep Window, the ABS shall not transmit DL traffic to the AMS and the AMS may power down one or more
physical operation components or perform other activities that do not require it to be available to receive DL
transmissions from the serving ABS.
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The transition between Active Mode and Sleep Mode is achieved only by means of negotiation using the MAC
Management messages such as MOB_SLP-REQ/RSP messages.
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The AMS and the ABS negotiate the operational values of the Sleep Mode parameters such as Initial Sleep Cycle, Final
Sleep Cycle, and Default Listening Window, by exchanging MOB_SLP-REQ/RSP message.
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15.2.1.2.
Sleep Mode entry
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Sleep Mode activation/entry is initiated either by an AMS or an ABS. An AMS in Active Mode may initiate Sleep Mode
by transmitting MOB_SLP-REQ message with Request_Code = 0b01 (i.e. 0b01: Enter Sleep Mode). The ABS shall send
MOB_SLP-RSP in response to the AMS’s request. In this case, if the AMS receives MOB_SLP-RSP message with
Response Code = 0b01 (i.e. 0b01: Approval of MOB_SLP-REQ) and Operation = 0b01 (i.e. 0b01: Enter Sleep Mode)
from the ABS, AMS shall transit from Active Mode to Sleep Mode in the frame designated by Start_Frame_Number in
the MOB_SLP-RSP message.
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An ABS may also request an AMS in Active Mode to enter Sleep Mode by transmitting MOB_SLP-RSP message with
Response Code = 0b00 (i.e. 0b00: Request by BS in Unsolicited manner) and Operation = 0b01 (i.e. 0b01: Enter Sleep
Mode) in an unsolicited manner.
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In the event that the ABS-initiated request (i.e. Unsolicited Sleep response) and an AMS-initiated request for Sleep Mode
entry is being handled concurrently, the ABS-initiated request shall take precedence over the AMS-initiated Request. In
this case, even though the AMS receives the ABS-initiated request while it is waiting for MOB_SLP-RSP message in
response to MOB_SLP-REQ, the AMS shall stop the remaining procedure of the AMS-initiated request and continue with
the ABS-initiated request. The ABS shall ignore an AMS request if the ABS has already initiated a change request.
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IEEE 802.16m-09/0640
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15.2.1.3.
Sleep Mode operation
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15.2.1.3.1.
Sleep Cycle operation
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The period of the sleep cycle is measured in units of frames. A sleep cycle is the sum of a Sleep Window and a Listening
Window. The first sleep cycle on entry to Sleep Mode from Active Mode does not contain a Listening Window.
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The Listening Window is located at the beginning of a Sleep Cycle. A Sleep Window follows the Listening Window and
continues to the end of the Sleep Cycle. In the case when the Listening Window is extended (see Subclause 15.2.1.3.4)
and the extension causes the Listening Window to occupy the full Sleep Cycle, the next Listening Window of the next
Sleep Cycle shall begin at its nominal location without an intervening Sleep Window. The ABS and the AMS shall
maintain synchronization related to the boundaries of the Sleep and Listening Windows.
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The Sleep Cycle may be changed implicitly. If there is negative indication in the traffic indication message or if there is
no data traffic during the Listening Window, the AMS and ABS shall update the length of the Sleep Cycle as follows:
Current Sleep Cycle = min( 2 x Previous Sleep Cycle, Final Sleep Cycle)………………….(x)
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If the AMS receives positive indication in the traffic indication message or DL traffic from an ABS, or transmits UL
traffic to the ABS, the AMS and the ABS shall reset the current Sleep Cycle to the Initial Sleep Cycle.
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The length of the Default Listening Window shall remain unchanged when Sleep Cycle is updated.
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15.2.1.3.2.
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In a Sleep Cycle, generally there is a Listening Window followed by a Sleep Window. An AMS’s behavior is described
below.
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Sleep Window & Listening Window operation
– During Sleep Window :
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
The AMS is unavailable to receive any DL data and MAC control signaling from the serving ABS.
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
The AMS may perform power-down or autonomous scan or any other autonomous operations that do not
involve the reception of DL transmissions.
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The AMS may send BW request message without exiting sleep mode.
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– During Listening Window :
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
The AMS can transmit/receive MAC PDUs to/from ABS only during the Listening Window.
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
The AMS shall ensure that it has up-to-date system information for proper operation. If the AMS detects that
the information it has, is not up-to-date (e.g. by monitoring Base Station ID, the Super Frame number and
change count of the system information), then it shall not transmit in the Listening Window until it receives
the up to-date system information.
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
The AMS with assigned SLPID shall receive and decode traffic indication message sent by an ABS
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
Extension of Listening Window may occur based on the existence of DL or UL traffic (see 15.2.1.3.4).
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
The Listening Window may be terminated before its current nominal end point (which have been extended
beyond the length of the Default Listening Window) by explicit signaling from ABS to AMS.
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15.2.1.3.3.
Traffic indication
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If Traffic Indication is enabled, an AMS shall wait for a traffic indication message. Upon receiving the traffic indication
message, the AMS shall check whether there is positive traffic indication (e.g. by the SLPID-Group Indication bit-map
and Traffic Indication bit-map or the SLPID assigned to it).
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If the AMS receives a negative indication in the traffic indication message and there is no pending UL traffic to transmit,
the AMS shall follow the Sleep Cycle update described in Equation above, and may immediately go back to sleep (i.e. the
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Sleep Window is deemed to have started immediately after the subframe in which the negative indication was sent). If the
AMS receives a positive indication in the traffic indication message or DL data traffic or the AMS has the pending UL
data traffic, the AMS shall reset the current Sleep Cycle to Initial Sleep Cycle. The AMS shall follow the termination rule
of Extended Listening Window (see 15.2.1.3.4)
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If the ABS transmits a negative indication to the AMS, the ABS shall not transmit any DL data traffic to the AMS during
the remaining part of the Listening Window, unless there are outstanding UL bandwidth requests from the AMS which
have not been fulfilled. If the ABS sends a positive indication to the AMS, the ABS should transmit at least one DL MAC
PDU containing data traffic during the AMS’s Listening Window
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15.2.1.3.4.
Listening Window extension
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An AMS shall wake up at the beginning of the Listening Window. It shall keep awake during the entire Listening
Window unless it receives a negative indication in the traffic indication message or an explicit indication to terminate the
Listening Window. The Listening Window can be extended as long as there is DL data traffic, UL data traffic or
BW-REQ with BR = non-zero, and an explicit indication to terminate the Listening Window has not been received. In this
case, the following process shall be performed in the AMS and the ABS.
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Data Traffic
Traffic Indication with
Positve Ind.
Traffic Indication with
Negative Ind.
MOB_SLP-RSP
MOB_SLP-REQ
A w ake S t.
S leep S t.
SW
SW
D LW
LW
LW E
SW
D LW
LW
IS C
1 st S C = IS C
2 nd S C = 2 x 1 st IS C
N o rm al
O p eratio n
S leep
M ode
A F ram e
S F : S uper Fram e
A S up er F ram e
D LW (D efault Listening W indow )
LW E (Listening W indow extension )
S W (S leep W indow )
LW : Listening W indow (D LW + LW E )
S C : S leep C ycle (LW + S W )
IS C : Initial S leep C ycle
N orm al O peration
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Figure XX an example of Sleep Mode operation
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Any exchange of MAC PDU between an AMS and an ABS during the Listening Window triggers an immediate start of
termination rule of Extended Listening Window in both AMS and ABS, as follows
– Termination rule of Extended Listening Window in an ABS

The ABS shall start T_ ABS timer. Whenever the ABS receives MAC PDU or HARQ ACK for DL data
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traffic from the AMS, the ABS shall reset and restart the T_ ABS timer.
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If the T_ ABS timer expires and the number of DL HARQ retransmission is exhausted for DL from the AMS,
the ABS shall regard the AMS as returning to sleep (i.e. the Sleep Window starts).
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If the ABS sends an explicit indication (e.g. DL sleep control header) to terminate the current Listening
Window, the ABS shall regard the AMS as returning to sleep (i.e. the Sleep Window starts)
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– Termination rule of Extended Listening Window in an AMS
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The AMS shall start T_ AMS timer. Whenever AMS receives MAC PDU or HARQ ACK for UL data traffic
from the ABS, the AMS shall reset and restart T_AMS timer.
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If the T_AMS timer expires and the number of UL HARQ retransmission is exhausted, the AMS shall return
back to sleep. In this case, the AMS should not transmit any PDU to the ABS until the next scheduled
Listening Window.
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If the AMS receives an explicit indication to terminate the current Listening Window, the AMS shall return
to sleep (i.e. the Sleep Window starts).
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15.2.1.3.5.
Sleep Mode change
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When an AMS enters Sleep Mode, an initial configuration of the Sleep Mode parameters shall be negotiated. During
Sleep Mode, this configuration may be changed by negotiating an update to the Sleep Mode parameters via explicit
signaling that is initiated by either the ABS or the AMS.
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An AMS in Sleep Mode may initiate a change to the Sleep Mode parameters by sending the MOB_SLP-REQ message
with Request_Code = 0b10 (i.e. 0b10: Change Sleep Mode). The ABS shall send the MOB_SLP-RSP message in
response to the AMS’s request for Sleep Mode change. The ABS may initiate a change to the Sleep Mode parameters by
sending the MOB_SLP-RSP message with Response_Code = 0b00 (i.e. 0b00: Request by ABS in Unsolicited Manner)
and Operation = 0b10 (i.e. 0b10: Change Sleep Mode) in unsolicited manner during the AMS’s Listening Window. After
a successful transaction, the first sleep cycle according to the updated parameters shall begin at the frame specified by
Start_Frame_Number in MOB_SLP-RSP message.
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In the event that an ABS-initiated request (i.e. Unsolicited Sleep response) and an AMS-initiated request for Sleep Mode
change is being handled concurrently, the ABS-initiated request shall take precedence over the AMS-initiated Request.
Therefore, if the AMS receives the ABS-initiated request while it is waiting for MOB_SLP-RSP message in response to
MOB_SLP-REQ, the AMS shall stop the remaining procedure of the AMS-initiated request and continue with the
ABS-initiated request. The ABS shall ignore an AMS-initiated request if it has initiated a change request.
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15.2.1.4.
Sleep mode Exit
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An AMS may initiate an exit from Sleep Mode anytime by transmitting MOB_SLP-REQ with Request_Code = 0b00 (i.e.
0b00: Exit from Sleep Mode). An ABS may also request an AMS to transit from Sleep Mode to Active Mode by
transmitting an unsolicited MOB_SLP-RSP message with Response Code = 0b00 (i.e. 0b00: Request by ABS in
Unsolicited Manner) and Operation = 0b00 (i.e. 0b00: Exit from Sleep Mode).
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In the event that the ABS-initiated request (i.e. Unsolicited Sleep response) and an AMS-initiated request for Sleep Mode
exit is being handled concurrently, the ABS-initiated request shall take precedence over the AMS-initiated Request. In
this case, even though the AMS receives the ABS-initiated request while it is waiting for MOB_SLP-RSP message in
response to MOB_SLP-REQ, the AMS shall stop the remaining procedure of the AMS-initiated request and continue with
the ABS-initiated request. The ABS shall ignore an AMS request if it has initiated a change request.
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Text End
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