Base Frame Structure for IEEE 802.16m

IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number:

IEEE S802.16m-08/081Date Submitted:

2008-01-xxSource:

Jerry Chow, Sean Cai, Qu Hongyun, Fang Huiying Voice: [Telephone Number (optional)]ZTE Corporation E-mail: jchow@zteusa.comJuejin Liu, Sean McBeath, Jianmin Lu, Lian Yang,Mingyang Sun {juejunliu, smcbeath, lujianmin}@huawei.comHuawei TechnologiesDong Xiaolu, Du Ying dongxiaolu@mail.ritt.com.cnCATRXiao Shanpeng, Liao Wenqi xiaoshanpeng@chinamobile.comChina MobileSuo Shiquiang suoshiquiang@datangmobile.com.cnDatang MobileSu Xin, Zhong Xiaofeng suxin@mail.tsinghua.edu.cnTsinghua University*<http://standards.ieee.org/faqs/affiliationFAQ.html>

Venue:IEEE 802.16m-07/047 – Call for Contributions on Project 802.16m System Description Document (SDD) – Frame Structure

Base Contribution:IEEE 802.16m-08/081

Purpose:Adopt proposed text in base contribution into Project 802.16m SDD under the topic of Frame Structure

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 >.

2IEEE S802.16m-08/081

802.16m Frame Structure:Framework Overview

3IEEE S802.16m-08/081

Design Approach for 16m Frame Structure• Define flexible framework

– 16m required to satisfy many diverse requirements, such as wide range of mobile speeds and wide range of coverage ranges

– To facilitate appropriate tradeoffs, avoid tightly coupling aspects that should be controlled independently (e.g. frequency of frame sync vs. frequency of DL/UL switching)

• Mitigate impact of legacy support on 16m operation– Maintain as much independence as possible between 16m and

legacy operation• Common framework for TDD, FDD, H-FDD, and multi-

carrier• Minimize control overhead while retaining sufficient

flexibility

4IEEE S802.16m-08/081

General 16m Frame Structure

Frame Partition

Frame

DL SubframePartition

UL SubframePartition

Frame Sync andControl

Time

Frequency

Frame PartitionControl

Frame Partition Frame Partition

Subframes

The depictions of the Frame Sync and Control and Frame Partition Control are meant to showgeneral location and do not imply any details of these elements such as size or shape .

NOTE :

5IEEE S802.16m-08/081

Main Elements of 16m Frame Structure

• Frame– Outer structure with synchronization signal(s) to allow MS to

acquire alignment with frame structure• Frame Partition

– Allows shorter timeframe than a frame for which decisions on allocations to MSs and radio resource configurations apply

• Subframe– A continuous duration within frame partition with transmissions

in a common direction (downlink or uplink)• Subframe Partition

– A continuous duration within subframe possessing particular PHY properties

6IEEE S802.16m-08/081

Main Elements of 16m Frame Structure (Cont’d)

• Unit Subframe– Smallest time unit structure within frame (above OFDM symbol)– Is comprised of one or more OFDM symbols and possibly time

gaps (idle times)– Has particular PHY structure and resource organization– Contains indivdiually addressable radio resource units

7IEEE S802.16m-08/081

Unit Subframe

Symbol1

Symbol2

. . . Symbolna

unit subframe

(a) DL unit subframe

Symbol1

Symbol2

. . . Symbolnb

unit subframe

(b) DL unit subframe with trailing idle time (for TDD)

TTG

(c) DL unit subframe with leading symbol used for sync signal

SyncSymbol

1

Symbol2

. . . Symbolnc

unit subframe

8IEEE S802.16m-08/081

Legacy Support via TDM in TDD Mode

16m TDD Frame (e.g. duration = 10 ms)

16m DL subframepartition

16m UL subframepartition

Legacy 16e TDDDL subframe

Legacy 16e TDDUL subframe

Legacy 16e TDDPreamble & MAPs

Segments of legacy 16e TDD sub-framesoccupy time slices reserved for them

16m Frame Syncand Control

Time

Frequency

Gaps in 16mframe allocatedas NULL sub-

frame partitionsfor Legacy 16e

use

DL UL

Legacy 16e TDD sub-frame may befragmented to reduce delay for 16m

operation

16m FramePartition Control

The depictions of the Frame Sync and Control and Frame Partition Control are meant to showgeneral location and do not imply any details of these elements such as size or shape .

NOTE:

Legacy 16e Frame (duration = 5 ms)

9IEEE S802.16m-08/081

Key Aspects of Legacy 16e Support

• Within 16m frame structure, reserve NULL sub-frame partitions for legacy 16e use

• 16m has separate frame boundary from legacy 16e– 16m frame has new Preamble distinct from the existing Preamble

for legacy 16e – allows independent operation for Legacy 16e MSs and new 16m MSs

• Fixed relative offset between start of 16m frame and start(s) of legacy 16e frames that reside within the time window of the 16m frame– Set 16m frame duration to be an integer multiple of the imbedded

legacy 16e frame(s)

10IEEE S802.16m-08/081

Key Aspects of Legacy 16e Support (Cont’d)

• Allow 16m subframe partition(s) of possibly opposite direction in between legacy 16e allocations within the legacy 16e DL or UL subframe– mitigate delay impact on 16m operation

• Can dynamically switch between 16m and legacy 16e use on 16m subframe-partition basis as long as directions (DL, UL) are same– e.g. subframe partitions designated for DL in 16m can be used

for 16e DL within the 16e DL subframe time

11IEEE S802.16m-08/081

FDD/Multi-carrier Via Simple Extension

Frame Partition

Frame

DL subframepartition

UL subframepartition

Frame Sync and Control

Time

Frequency

Frame Partition Control

Frame Partition Frame Partition

Tf,offset

{

{

Frame Partition

Tfp,offset

Subframe Subframe Subframe Subframe

DLCarrier

ULCarrier

12IEEE S802.16m-08/081

Key 16m Frame Structure Attributes

• Common frame structure elements and control as used for 16m TDD frame

• Define FDD case as a subset case of general operation with multiple-carrier BS– Should be same configuration and control mechanisms– Main characteristic of FDD sub-case is that main carrier is

configured to have only DL sub-frames and an auxiliary carrier is configured to have UL sub-frames only

• H-FDD supported in framework via appropriate offset of corresponding frame partitions between DL and UL carriers

13IEEE S802.16m-08/081

802.16m Frame Structure:Considerations on Preamble

14IEEE S802.16m-08/081

Preamble – Option 1

The 16m frame preamble in the Frame Sync and Control signal is located at the start of the 16m frame.

15IEEE S802.16m-08/081

Preamble – option 2

• The frame preamble consists of three OFDM symbols, which are located at the end of a DL subframe, which precedes an UL subframe.

• The cyclic prefix length of the P-SCH and S-SCH is fixed.

16IEEE S802.16m-08/081

Preamble – option2 (cont.)

• Superframe Preamble– 2 OFDM Symbols (P-SCH and S-SCH) with a fixed cyclic prefix

length• P-SCH

– Located in the center of the traffic bandwidth– Occupies 5 MHz bandwidth (around the center frequency when bandwidth is

above 5MHz )• S-SCH

– Sector Identity

• Broadcast Channel (BCH) contains the following information:– CP length for the traffic symbols– The size of the multicast control segment– Antenna configuration– Other content for further study

17IEEE S802.16m-08/081

802.16m Frame Structure:Example Configuration

andDetails on Resource Control within

Unit Subframe

18IEEE S802.16m-08/081

Example Configuration of 802.16m Frame

0 1 2 3 frame partitions

subframes

unit subframes(comprising OFDM symbols)

frames

5 msec

20 msec

Frame Sync and

Control

Frame Partition Control

21

0 1 2 3 4 5

subframe partitions

19IEEE S802.16m-08/081

Unit Subframe Resource Addressing via Channel Tree

• To reduce control channel overhead, a channel tree is defined for 16m.– A unique channel tree is defined within each unit subframe (or

within subframe partition TBD)

• A channel tree is defined by its base-nodes.– Tradeoff between resource granularity and control channel

overhead must be considered.– One base node: 14 subcarriers (data + traffic) × 6 OFDM

symbols• 10 MHz = 60 base nodes• 5 MHz = 30 base nodes

• Other resource assignment method is under consideration

20IEEE S802.16m-08/081

Unit Subframe Resource Addressing (Opt. 1)

Option 1: Organized as Nodes in Annular Channel Tree

unicast control segment

null base nodes

traffic

32 Base Node Example

Base nodes on outside of circle

Parent nodes on inside of circle

21IEEE S802.16m-08/081

Unit Subframe Resource Addressing (Opt. 2)

Option 2: Organized as Hybrid Between Binary Channel Tree and Bitmap

Example 1: Parent Node 6 + bitmap ‘1000’ = base node 27Example 2: Parent Node 4 + bitmap ‘1110’ = base nodes 19, 20, 21Example 3: Parent Node 0 + bitmap ‘1100’ = channel tree nodes 3, 4

This delineation is a system parameter,

thereby making the assignment

overhead flexible.

22IEEE S802.16m-08/081

Unit Subframe Control Channels

• The control channel is composed of two pieces: multicast and unicast– The multicast control segment contains the following

information, which is jointly encoded:• Indication of the division of the frequency domain into multiple

subzones• Subcarrier permutation• Other content for further study

– Multiple unicast control segments are defined, where each segment contains one assignment• The unicast assignments are located at the beginning of each

subzone– The assigned time-frequency resource is not restricted to the

corresponding subzone

23IEEE S802.16m-08/081

Unit Subframe Control Channels (Cont’d)

subzone 1

subzone 2

subzone 3

subzone 4

unicast control segment

multicast control segment

traffic

6 OFDM Symbols