1 / 16

Project IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>

Title Expedited Hard Handover

Date Submitted

2008-01-17

Source(s) Baowei Ji, Changhoi Koobji@sta.samsung.com, chkoo@samsung.com Samsung Telecommunications America

Re: TGm Call for Contributions on SDD, IEEE 802.16m-07/047 Topic: Proposed 802.16m Protocol Architecture and main functionalities per protocol layer

Abstract Enhanced Handoff procedures and Messaging should be taken into 802.16m systems as a new discussion feature, because conventional HHO cannot meet 802.16m requirement, and Optimized HHO may not function. We propose to add a new section and/or description for the enhanced handoff operation in SDD. The proposed Expedited HHO in this proposal could be one of solutions for meeting 802.16m requirements.

Purpose Discuss the problem with Optimized Handover, and propose Expedited HHO to meet the requirement in 802.16m

Notice 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.

Release 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.

Patent Policy

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>.

IEEE C802.16m-08/016r2

2 / 16

Long HO Interruption Time in Conventional HHO

MSServing

BSAnchor

ASNTarget

BSAuthenticator

ASN

MOB_MSHO_REQ

HO-Request

Context Transfer

Bearer Path Registration

HO-Response

MOB_BSHO_RSP

MOB_HO_IND

HO-Ack

HO-Confirm

HO-Ack

Handover RangingRanging Code

RNG-RSP & Resource alloc. For RNG-REQ via UL-MAP

RNG-REQ

RNG-RSP (HO Proc. Opt.)

Operational (data transfer)

Bearer Path De-registration

CMAC Key CountUpdate Proc.

HO

pre

pa

ratio

n t

ime

Freq. & DLSync.

Ranging & Grant

UL signaling

DL signaling

HO

inte

rru

ptio

n t

ime

• Difficulty for meeting HO interruption time below 30 msec

3 / 16

Attempt of Optimized HHO (1/4)

MSServing

BSAnchor

ASNTarget

BSAuthenticator

ASN

MOB_MSHO_REQ

HO-Request

Context Transfer

Bearer Path Registration

HO-Response

MOB_BSHO_RSP

MOB_HO_IND

HO-Ack

HO-Confirm

HO-Ack

Fast_Ranging_IE ()& Resource alloc. For RNG-REQ via UL-MAP

RNG-REQ

RNG-RSP (HO Proc. Opt.)

Operational (data transfer)

Bearer Path De-registration

CMAC Key CountUpdate Proc.

HO

pre

para

tion

time

Sync. & Grant

UL signaling

DL signaling

HO

inte

rrup

tion

time

4 / 16

Attempt of Optimized HHO (2/4)

5 / 16

Attempt of Optimized HHO (3/4)Receive MOB_NBR_ADV (serving BS)

Send MOB_SCN_REQ (serving BS)

Receive MOB_SCN_RSP (serving BS)

Scanning neighbor BSs

Send MOB_MSHO_REQ (serving BS)

Receive MOB_BSHO_RSP (serving BS)

Send MOB_HO_IND (serving BS)

Send RNG-REQ (target BS)

Receive RNG-RSP (target BS)

Receive Fast_Ranging_IE (target BS)

Need to scan neighbor?

Is HO criterion met?

No

No

Yes

Yes

MS initiated HO process block diagram as seen by MS (in 802.16e)

6 / 16

Attempt of Optimized HHO (4/4)

Receive MOB_NBR_ADV (serving BS)

Send MOB_HO_IND (serving BS)

Send RNG-REQ (target BS)

Receive RNG-RSP (target BS)

Receive Fast_Ranging_IE (target BS)

Receive MOB_BSHO_REQ (serving BS)No

Yes BS initiated HO process block diagram as seen by MS (in 802.16e)

7 / 16

Problem with Optimized HHO (1/4)

• Without parameter adjustment, especially timing adjustment, RNG-REQ might arrive outside of the guard interval, fails to be detected by the target BS.

8 / 16

Problem with Optimized HHO (2/4)

• Initial ranging shall use an initial ranging code in an initial ranging slot– TDD: power and frequency could be adjusted autonomously after

downlink synchronization

– Timing may not be adjusted without handshaking

9 / 16

Problem with Optimized HHO (3/4)

• Optimized HHO may incur even longer interruption time than conventional HHO does

10 / 16

Problem with Optimized HHO (4/4)

MSServing

BSAnchor

ASNTarget

BSAuthenticator

ASN

MOB_MSHO_REQ

HO-Request

Context Transfer

Bearer Path Registration

HO-Response

MOB_BSHO_RSP

MOB_HO_IND

HO-Ack

HO-Confirm

HO-Ack

Handover RangingRanging Code

RNG-RSP & Resource alloc. For RNG-REQ via UL-MAP

RNG-REQ

RNG-RSP (HO Proc. Opt.)

Operational (data transfer)

Bearer Path De-registration

CMAC Key CountUpdate Proc.

HO

pre

para

tion

time

DL Sync. & UL Grant

Ranging & Grant

UL signaling

DL signaling

HO

inte

rrup

tion

time

Fast_Ranging_IE ()& Resource alloc. For RNG-REQ via UL-MAP

RNG-REQ Decode failure

Discarded by BSTimeout

11 / 16

Proposed Expedited HHO (1/5)

MSServing

BSAnchor

ASNTarget

BSAuthenticator

ASN

MOB_MSHO_REQ

HO-Request

Context Transfer

Bearer Path Registration

HO-Response

MOB_BSHO_RSP

MOB_HO_IND

HO-Ack

HO-Confirm

HO-Ack

Fast_First_Ranging_IE() & Resource alloc. For RNG-REQ via UL-MAP

Ranging Code 0

RNG-RSP (HO Proc. Opt.)

Operational (data transfer)

Bearer Path De-registration

HO

pre

para

tion

time

Sync. & Grant

UL signaling

DL signaling

HO

inte

rrup

tion

time

12 / 16

Proposed Expedited HHO (2/5)

Table 2- OFDMA Fast_First_Ranging_IE() format

Syntax Size Notes

Fast_First_Ranging_IE{  

Extended UIUC 4 bits Fast_First_Ranging_IE() = 0x0B

HO ID 8 bits Assigned by the targeting BS

OFDMA symbol offset 8 bits  

Subchannel offset 7 bits  

No. OFDMA symbols 7 bits  

No. subchannels 7 bits  

Ranging method 1 bit0- Ranging over 2 symbols1- Ranging over 4 symbols

reserved 6 bits Shall be set to zero

}  

13 / 16

Proposed Expedited HHO (3/5)

MS initiated HO process block diagram as seen by MS (in 802.16m)

Receive MOB_NBR_ADV (serving BS)

Send MOB_SCN_REQ (serving BS)

Receive MOB_SCN_RSP (serving BS)

Scanning neighbor BSs

Send MOB_MSHO_REQ (serving BS)

Receive MOB_BSHO_RSP (serving BS)

Send MOB_HO_IND (serving BS)

Send Ranging Code 0 (target BS)

Receive RNG-RSP (target BS)

Receive Fast_First_Ranging_IE (target BS)

Need to scan neighbor?

Is HO criterion met?

No

No

Yes

Yes

14 / 16

Proposed Expedited HHO (4/5)

BS initiated HO process block diagram as seen by MS (in 802.16m)

Receive MOB_NBR_ADV (serving BS)

Send MOB_HO_IND (serving BS)

Send Ranging Code 0 (target BS)

Receive RNG-RSP (target BS)

Receive Fast_First_Ranging_IE (target BS)

Receive MOB_BSHO_REQ (serving BS)No

Yes

15 / 16

Proposed Expedited HHO (5/5)

Table 3 (modified Table 290a) Extended UIUC Code Assignment for UIUC = 15

Extended UIUC(hexadecimal)

Usage

00 Power_control_IE

01 reserved

02 AAS_UL_IE

03 CQICH_Alloc_IE

04 UL_Zone_IE

05 PHYMOD_UL_IE

06 Reserved

07 UL-MAP_Fast_Tracking_IE

08 UL_PUSC_Burst_Allocation_in_Other_Segment_IE

09 Fast_Ranging_IE

0A UL_Allcoation_Start_IE

0B Fast_First_Ranging_IE

0C … 0F reserved

16 / 16

Conclusions

• Enhanced Handoff procedures and Messaging should be taken into 802.16m systems as a new discussion feature, because – Conventional HHO cannot meet 802.16m requirement

– Optimized HHO may not function

• We propose to add a new section and/or description for the enhanced handoff operation in SDD– The proposed Expedited HHO in this proposal could be one of

solutions for meeting 802.16m requirements