IEEE C802.16m-08/327
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
High Level Views on Multicarrier Operations for IEEE 802.16m
Date
Submitted
2008-05-05
Source(s)
Kelvin Chou, Yih-Shen Chen, I-Kang Fu and
Paul Cheng
Kelvin.Chou@mediatek.com
Yihshen.Chen@mediatek.com
IK.Fu@mediatek.com
MediaTek Inc.
No.1, Dusing Rd. 1, HsinChu Science-Based
Industrial Park, HsinChu, Taiwan 300, R.O.C.
Re:
IEEE 802.16m-08/016, “Call for Contributions on Project 802.16m System Description
Document (SDD)”. In response to the following topics:
• Comments on the entire content of IEEE 802.16m-08/003r1
Abstract
This contribution proposes the system state and working flow for the 802.16m system with the
support of multiple RF carriers.
Purpose
To be discussed and adopted by TGm for the 802.16m SDD.
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 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
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<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>.
High Level Views on Multicarrier Operations for IEEE 802.16m
Kelvin Chou, Yih-Shen Chen, I-Kang Fu, and Paul Cheng
MediaTek Inc.
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IEEE C802.16m-08/327
1. Introduction
This contribution studies the system state and working flow for the 802.16m mobile stations with the support of
multiple RF carriers. Firstly, a systematic method is used to get an enumeration of all possible states of the 16m
system with multicarrier support. Then, several assumptions and considerations are proposed as regulations for
the design of a practical multi-band OFDMA system. Using these regulations we eliminate infeasible states from
the enumerative ones. Finally, the system operation flow for the multicarrier supported 16m system is derived
from the revised system states. We hope the design flow presented in this contribution can provide a complete
view of the 16m system and its functionalities.
2. Overview of the Multicarrier System
With the support of multiple RF carriers, the overall state of a 16m MS is determined by the current behavior of
each individual RF carrier. An RF can be categorized into one of the following five states according to its
current activities: power off state, initial state, access state, connected state and idle state. Since there is one
common MAC for all the RF carriers, the MAC state can be further defined by the combination of all its RF
states, as illustrated in Figure 1.
802.16m MS
MAC
RF 1
RF 2
RF n
Power Off
Power Off
Power Off
Initial
Initial
Initial
Access
Access
Access
Connected
Connected
Connected
Idle
Idle
Idle
Figure 1. Overview of the MS with multiple RF carriers
A general description of each RF state is given as follows:
2.1 Initial State
An RF is in initial state if it is doing one of the following operations:
- Scanning and synchronizing to the DL channel.
- Obtaining transmission parameters from the downlink broadcast information.
2.2 Access State
An RF is in access state if it is trying to connect to the BS and set up connections between each other, which
include the following operations: ranging, basic capabilities negotiation, authentication/key exchange,
registration, set up basic connections, and IP address acquisition.
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IEEE C802.16m-08/327
2.3 Connected State
An RF is in connected state if it maintains at least one established connection with the BS. The established
connection can be in either sleep mode or not.
2.4 Idle State
An RF is in idle state if it is in idle mode.
2.5 States Transitions
The RF state combinations and transitions can be described using a Markov chain. To simplify the discussion,
we consider a MS with two RF carriers with the following assumptions:
1) The RF can go back to connected state from idle state directly through some fast network reentry processes.
2) The RF goes to power off state from the initial state (although it can go off from any state).
The RF states are numbered from 0 to 4 respectively (0: power off state, 1: initial state, 2: access state, 3:
connected state, 4: idle state). The state of the Markov chain is represented by the state combination of all RF
carriers, e.g. (state of RF1, state of RF2), and the transition between Markovian states is represented by Told_statenew_state. For example, (0,0) is the state in which both RF carriers are in power off state, and T00-10 represents the
transition from state (0,0) to state (1,0) in which RF1 is in initial state. Figure 2 illustrates all the state
combinations and transitions of the MS with two RF carriers.
0,4
1,4
2,4
4,3
4,4
0,3
1,3
2,3
3,3
4,3
0,2
1,2
2,2
3,2
4,2
0,1
1,1
2,1
3,1
4,1
0,0
1,0
2,0
3,0
4,0
T00-01
State: (RF1, RF2)
0: Power off state
1: Initial state
2: Access state
3: Connected state
4: Idle state
T10-00
Figure 2. The state transition diagram of the MS with two RF carriers
3. Design Considerations for the Multi-carrier Operations
Now we make the following assumptions for the multi-carrier operations in the 16m system design, and to
eliminate impractical Markovian states from Figure 2.
First, we start with some terminologies:
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IEEE C802.16m-08/327
- The term “band group” is used to represent a set of contiguous frequency bands in this document.
- The term “master FA (MFA)” is used to represent a FA with fixed frequency without frequency offset in
this document.
Now we make the following assumptions for the multi-carrier operations in the 16m system design:
3.1 BS frequency assignment
1. A BS supporting multi-band frame structure may support multiple band groups.
2. There is at least one MFA per group.
3. All the FAs in a group without subcarrier alignment can be MFAs.
4. A subcarrier-aligned group shall include at least one MFA.
3.2 NW entry
1. Each MFA broadcasts (e.g., via PBCH) necessary system information for network entry.
2. The PBCH may optionally broadcast (e.g. via SBCH) the frequency offset information of other FAs in the
same group.
3. An MS which wants to perform initial network entry synchronizes with the MFA, derives system
information of the MFA and possibly other FAs, and performs network entry through the MFA.
4. In case the frequency offset information of other FAs is available, the MS may perform network entry
through other FAs.
5. The algorithm to select the FA from all available FAs for NW entry is for further study (or may be out of the
802.16m scope).
6. After the NW entry is done, the BS may relocate the MS to another FA by intra-group handover operation.
3.3 Handover
In a multi-carrier supported MS, the handover operations can be done via the RF carrier different from the one
connecting to the MFA of its SBS. In that case, the normal operations (e.g. data transmission) can proceed until
the RF carrier performing handover operations has successfully connected to the MFA of the target BS.
3.4 MS RF module activation and deactivation
1. The RF modules of a multi-carrier supported MS should be activated one by one. For example, in the case of
the MS with two RF modules, the second RF module should not be initialized until the first RF module has
reached its connected state.
2. In case of the RF carrier connecting to the MFA (or the FA which carries PBCH) of the Serving BS being
dropped, the remaining RF carriers which are accessing the non-MFAs of the Serving BS but have not
reached the connected state should abort their current operations and go back to power off state. RF carriers
which are performing NW entry to the BS other than the Serving BS should not be affected.
3. The MS should have only one RF carrier in idle state. In that case, all the other RF carriers should be
powered off.
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IEEE C802.16m-08/327
3.5 The revised 16m MS system states
Based on the above assumptions, the enumerative Markovian states in Figure 2 can be refined into the following
one illustrated in Figure 3.
0,4
0,3
1,3
2,3
3,3
0,2
3,2
0,1
3,1
T00-10
0,0
1,0
2,0
3,0
4,0
State: (RF1, RF2)
0: Power off state
1: Initial state
2: Access state
3: Connected state
4: Idle state
T10-00
Figure 3. The revised system state diagram for the 16m MS with two RF carriers
3.6 Proposed MS Operation Flows
Based on the thinking aforementioned, the system flow of a MS with N RF carriers (labeled as RF#1 to RF#N)
can be derived as follows and is illustrated in Figure 4. The numbering of the RF carriers may be mapped to the
physical RF carriers in an arbitrary order depending on the system configuration. The system flows are
described as follows.
After the MS is powered on, its primary carrier (RF#1) is initialized first. The MS performs cell search via RF#1
to locate the cell and band it wishes to join. The cell search procedures include primary bands identification,
system information acquisition, cell selection, and band selection. The BS may broadcast the information of its
primary bands and other alternative bands for the MS to expedite its synchronization process.
Once the target BS (and band) has been decided, the MS performs network entry procedures to establish basic
connections with the target BS. During the network entry, the MS and BS negotiate their multi-carrier
capabilities as a reference for further scheduling. After network entry procedures are done, the target BS
becomes the serving BS of the MS, and the MS starts its normal operations.
The MS may perform its normal operations, such as data transmission, scanning, handover decision and EMBS,
using single RF carrier (RF#1). It may also enable additional RF carriers to assist its normal operations. The
initialization and network entry process of the supplementary RF carrier may be simplified with the assistance
of currently active carriers. The functionalities of the supplementary RF carrier (blocks with dash lines in Figure
4) may be performed or skipped according to the requirement of its dedicated operations.
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IEEE C802.16m-08/327
RF#N
RF#3
RF#2
RF power on
RF
Cell search
power on
Primary /
Cell search
secondary
Cell search
Primary / bands
secondary
Primary
/ identification
bands
secondary
identification
bands
identification System
information
Systemacquisition
information
System
acquisition
information
acquisition
Cell/band
selection
Cell/band
selection
Cell/band
selection
Network entry
Network entry
Network entryMulti-carrier
capability
Multi-carrier
negotiation
Multi-carrier
capability
capability
negotiation
negotiation
Normal operations
Data
Normal operations
transmission
Normal operations
Data
transmission
Data
transmission EMBS
EMBS
Fast network
entry
FastFast
network
network
entryentry
Scanning
EMBS
Scanning
Scanning
MS
System On
RF#1
RF
power on
Enable
supplementary
RF
Multi-carrier assisted operations
Cell search
Network entry
Primary bands
identification
Multi-carrier
capability
negotiation
Data
transmission
Scanning
System
information
acquisition
Fast network
entry
EMBS
Handover
decision
RF power off
RF
power off
Normal operations
Cell/band
selection
Idle
RF
power off
Disable
supplementary
RF
MS
System off
Figure 4. MS operation flow with multiple RF carriers
Proposed Text for SDD
[In 80216m-08_003r1, add the following subsection to Section 19]
------------------------------- Text Start ------------------------------------------------------------------------------------
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IEEE C802.16m-08/327
19.1 Multicarrier System Overview
With the support of multiple RF carriers, the overall state of a 16m MS is determined by the current behavior of
each individual RF carrier. An RF can be categorized into one of the following five states according to its
current activities: power off state, initial state, access state, connected state and idle state. Since there is one
common MAC for all the RF carriers, the MAC state can be further defined by the combination of all its RF
states, as illustrated in Figure XX.
802.16m MS
MAC
RF 1
RF 2
RF n
Power Off
Power Off
Power Off
Initial
Initial
Initial
Access
Access
Access
Connected
Connected
Connected
Idle
Idle
Idle
Figure XX. MS system states with multiple RF carriers
A general description of each RF state is given as follows:
19.1.1 Initial state
An RF is in initial state if it is doing one of the following operations:
- Scanning and synchronizing to the DL channel.
- Obtaining transmission parameters from the downlink broadcast information.
19.1.2 Access state
An RF is in access state if it is trying to connect to the BS and set up connections between each other, which
include the following operations: ranging, basic capabilities negotiation, authentication/key exchange,
registration, set up basic connections, and IP address acquisition.
19.1.3 Connected state
An RF is in connected state if it maintains at least one established connection with the BS. The established
connection can be in either sleep mode or not.
19.1.4 Idle state
An RF is in idle state if it is in idle mode.
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IEEE C802.16m-08/327
19.1.5 MS system flows
The system flow of a MS with N RF carriers (labeled as RF#1 to RF#N) is illustrated in Figure YY. The
numbering of the RF carriers may be mapped to the physical RF carriers in an arbitrary order depending on the
system configuration. The system flows are described as follows.
After the MS is powered on, its primary carrier (RF#1) is initialized first. The MS performs cell search via RF#1
to locate the cell and band it wishes to join. The cell search procedures include primary bands identification,
system information acquisition, cell selection, and band selection. The BS may broadcast the information of its
primary bands and other alternative bands for the MS to expedite its synchronization process.
Once the target BS (and band) has been decided, the MS performs network entry procedures to establish basic
connections with the target BS. During the network entry, the MS and BS negotiate their multi-carrier
capabilities as a reference for further scheduling. After network entry procedures are done, the target BS
becomes the serving BS of the MS, and the MS starts its normal operations.
The MS may perform its normal operations, such as data transmission, scanning, handover decision and EMBS,
using single RF carrier (RF#1). It may also enable additional RF carriers to assist its normal operations. The
initialization and network entry process of the supplementary RF carrier may be simplified with the assistance
of currently active carriers. The functionalities of the supplementary RF carrier (blocks with dash lines in Figure
YY) may be performed or skipped according to the requirement of its dedicated operations.
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IEEE C802.16m-08/327
RF#N
RF#3
RF#2
RF power on
RF
Cell search
power on
Primary /
Cell search
secondary
Cell search
Primary / bands
secondary
Primary
/ identification
bands
secondary
identification
bands
identification System
information
Systemacquisition
information
System
acquisition
information
acquisition
Cell/band
selection
Cell/band
selection
Cell/band
selection
Network entry
Network entry
Network entryMulti-carrier
capability
Multi-carrier
negotiation
Multi-carrier
capability
capability
negotiation
negotiation
Normal operations
Data
Normal operations
transmission
Normal operations
Data
transmission
Data
transmission EMBS
EMBS
Fast network
entry
FastFast
network
network
entryentry
Scanning
EMBS
Scanning
Scanning
MS
System On
RF#1
RF
power on
Enable
supplementary
RF
Multi-carrier assisted operations
Cell search
Network entry
Primary bands
identification
Multi-carrier
capability
negotiation
Data
transmission
Scanning
System
information
acquisition
Fast network
entry
EMBS
Handover
decision
RF power off
RF
power off
Normal operations
Cell/band
selection
Idle
RF
power off
Disable
supplementary
RF
MS
System off
Figure YY. MS operation flow with multiple RF carriers
------------------------------- Text End
------------------------------------------------------------------------------------
9