An Overview of IEEE 802.16m Radio Access Technology Globecom 2010

Dr. Sassan Ahmadi
Principal Engineer and Chief Architect, 4G Wireless Systems

Intel Architecture Group
Wireless Technology Division
Intel Corporation

December 6, 2010

 Road to 4th Generation of Cellular Systems
 Mobile WiMAX Network Architecture
 IEEE 802.16m Protocol Structure and System Operation
 MAC Layer
 Physical Layer
 IEEE 802.16m Mixed-Mode (Legacy) Operation
 IEEE 802.16m Performance Evaluation
 References

 Note: For more detailed information on IEEE 802.16m standard see the following
book:
• Mobile WiMAX, A Systems Approach to Understanding IEEE 802.16m Radio
Access Technology, Sassan Ahmadi, Academic Press, November 2010

Sassan Ahmadi/IEEE GLOBECOM 2010/December 2010 2

2007 2010

Cellular (3GPP)
1G 2G 3G
LTE/LTE-Advanced
Analog TDMA WCDMA

Broadband Wireless IEEE IEEE IEEE 802.16m
(WiMAX) 802.16-2004 802.16-2009

Wireless LAN IEEE
IEEE 802.11a/b/g IEEE 802.11n
(Wi-Fi) 802.11ac/ad

OFDMA + MIMO New Spectrum
All-IP Core Network

Sassan Ahmadi/IEEE GLOBECOM 2010/December 2010

Mobility
New capabilities of Systems Beyond IMT-2000

High New
Mobile
Enhanced Access
4G
IMT-2000
IMT-2000 Next Generation
3G of mobile WiMAX .

Evolution
mobile WiMAX

New Nomadic / Local
Low Area Wireless Access

1 10 100 1000

Peak Useful Data Rate (Mbits/s)

ITU-R Recommendation M.1645 Vision for Systems beyond IMT-2000


 The key features of IMT-Advanced systems can be summarized as
follows:
• Enhanced cell and peak spectral efficiencies, and cell-edge user
throughput to support advanced services and applications
• Lower air-link access and signaling latencies to support delay sensitive
applications
• Support of higher user mobility while maintaining session connectivity
• Efficient utilization of spectrum
• Inter-technology interoperability, allowing worldwide roaming capability
• Enhanced air-interface-agnostic applications and services
• Lower system complexity and implementation cost
• Convergence of fixed and mobile networks
• Capability of interworking and coexistence with other radio access
systems


50
Background
Services
BER < 10-6

10
Data Rate (Mbps)

Streaming Services
10-9 < BER < 10-6

5

Interactive Services
1 10-9 < BER < 10-6

0.5
Conversational
Services
10-6 < BER < 10-3

10 100 1000
Delay (ms)

Four service classes specified for IMT-Advanced systems (conversational, interactive,
streaming, background services) and their characteristics in terms of reliability, bit rate,
and latency


High Mobility New Mobile Access
(120 – 500 km/h)

IMT-Advanced
Enhanced Systems
IMT 2000 ,
cy
Systems a ten s
IMT 2000 g L i ce
Systems a sin erv
re S
ec ing
s , D reas
ate , Inc
ta R ility
Da ob New Nomadic/Local
Low Mobility/
s ing ng M
Nomadic rea rovi Wireless Access
(0 – 30 km/h) Inc Imp

1 10 100 1000

Layer 2 Data Rate (Throughput at MAC Layer) Mbps

The services and performance of the systems noticeably increased as the
systems evolve from one generation to another.


Requirements IMT-Advanced IEEE 802.16m
Peak spectrum efficiency DL: 15 (44) DL: 8.0/15.0 (22/44)
(bit/sec/Hz) (system-level) UL: 6.75 (24) UL: 2.8/6.75 (1x2/2x4)
DL: (4x2) = 2.2 DL: (2x2) = 2.6
Cell spectral efficiency
UL: (2x4) = 1.4 UL: (1x2) = 1.3
(bit/sec/Hz/sector) (system-level)
(Base coverage urban) (Mixed Mobility)
DL: (4x2) = 0.06 DL: (2x2) = 0.09
Cell-edge user spectral efficiency (bit/sec/Hz)
UL: (2x4) = 0.03 UL: (1x2) = 0.05
(system-level)
(Base coverage urban) (Mixed Mobility)
Latency (ms) C-plane: 100/U-plane: 10 C-plane: 100(idle to active); U-plane: 10
Optimal performance up to 10 km/h; Graceful: degradation up to
Mobility 0.55 at 120 km/h
120 km/h; Connectivity up to 350 km/h; Up to 500 km/h
bit/sec/Hz (link-level) 0.25 at 350 km/h
depending on operating frequency
Intra frequency: 27.5
Intra frequency: 27.5; Inter frequency: 40 (in a band); 60
Handover interruption time (ms) Inter frequency: 40 (in a band)
(between bands)
60 (between bands)
VoIP capacity 40 (4x2 and 2x4)
60 (DL: 2x2 and UL: 1x2)
(Active users/sector/MHz) (system-level) (Base coverage urban)
DL: 2x2 (baseline), 2x4, 4x2, 4x4, 8x8
Antenna Configuration Not specified
UL: 1x2 (baseline), 1x4, 2x4, 4x4
Cell Range and Coverage Not specified Up to 100 km; Optimal performance up to 5 km
Multicast and Broadcast Service (MBS) 4 bit/sec/Hz for ISD 0.5 km
Not specified
(system-level) 2 bit/sec/Hz for ISD 1.5 km
MBS channel reselection interruption time Not specified 1.0 sec (intra-frequency); 1.5 sec (inter-frequency)
Location determination latency <30 sec; MS-based position
Location based services (LBS) Not specified determination accuracy <50 m; Network-based position
determination accuracy <100 m
Up to 40 MHz
Operating bandwidth 5 to 20 MHz (up to 100 MHz through band aggregation)
(with band aggregation)
Duplex scheme Not specified TDD, FDD (support for H-FDD terminals)
Operating frequencies IMT Bands IMT Bands


Source Destination

Application Layer Application Layer

Presentation Layer Presentation Layer

Logical Protocol Links
Session Layer Session Layer

Transport Layer Transport Layer
Layer-3 Signaling

Network Layer Network Layer Network Layer Network Layer

1 2 3 4
User-Plane Latency
User-Plane Latency
Transmit Reference Data-Link Layer Data-Link Layer
Data-Link Layer Data-Link Layer Receive Reference Point
Point

Physical Layer Physical Layer Physical Layer Physical Layer

Intermediate Network Nodes

Logical Data Path

Layer-2 Signaling Radio Air-Interface

The user-plane latency is defined as the one-way transit time between a packet being
available at the IP layer of the origin and the availability of this packet at IP layer of the
destination. The user-plane packet delay includes delay introduced by associated protocols
and signaling assuming the user terminal is in the active-mode.


NAP Visited NSP Home NSP
R2

R1 R3 R5
ASN1 Visited Home
MS CSN
CSN

Control
Plane

Bearer R4
Plane

ASP Network/ ASP Network/
ASN2 Internet Internet

The network reference model is a logical representation of the network architecture. The
NRM identifies functional entities and reference points over which interoperability is
achieved. The WiMAX NRM consists of MS, ASN, and CSN, which are described in the
following sections. The interfaces R1-R8 are normative reference points.


Bearer Path ____
R6 Control Path - - - -
Data Path R1
Authenticatiion
Function ASN-GW BS1
R3
Handover Key R8 ASN-GW1
Function Distribution
R1
RRM Relay R4 BS2
Context Function DHCP Proxy R6
Paging R3 R4
Proxy Mobile Control Service Flow R1 R6
IPClient Authentication BS3
Location
R4
Register Mobile IP FA
AAA Client R8 ASN-GW2
R1
BS4
R6 R6
ASN

Data Path Context Radio Resource
Function Function Agent The ASN comprises network elements
Radio
Resource
such as one or more base stations and
R1 R8
Handover Control Authentication one or more ASN Gateways (ASN-GW).
Function Relay
An ASN may be shared by more than one
Paging Agent
Connectivity Service Networks (CSN). The
Service Flow
Management BS Key Receiver radio resource control functions in the BS
would allow Radio Resource Management
(RRM) within the BS. The CSN is defined
ASN as a set of functions that provide IP
connectivity to user terminals.


CSN
(MIP HA)

R3 R3
Inter-ASN R3 Mobility

ASN-GW R4 ASN-GW
(MIP FA) (MIP FA)

R6 Intra-ASN R6 Mobility R6 R6

R8
BS1 BS2 BS3

Intra-ASN R8 Mobility

MS MS MS MS
Direction of Motion
1 2 3 4

Three different mobility scenarios are supported in WiMAX networks. When the mobile
station moves from positions 1 to 2 or 1 to 3, an ASN-anchored mobility through R8 or R6
reference points, respectively, is involved, whereas moving from position 1 to 4 involves a
CSN-anchored mobility scheme though R3 reference point.


The paging reference model can be decomposed into three separate functional entities:
 Paging Controller administers the activity of an idle-mode MS in the network. It is identified by a
PC Identifier and can either be collocated with the BS or separate from the BS across R6
reference point.
 Paging Agent manages the interaction between the PC and IEEE 802.16 specified paging
related functionality implemented in the BS. A PA is collocated with the BS.
 Paging Group consists of one or more Paging Agents. A Paging Group resides entirely within a
NAP boundary and is managed and provisioned by the network operator.
 Location Register is a distributed database with each instance corresponding to an Anchor PC.
Location registers contain information about mobile stations in Idle State. The information for each
MS includes current Paging Group ID, paging cycle, paging offset, last reported BS Identifier, last
reported Relay PC ID.
Location Location
Register Register

R4
Paging Paging
Controller Controller

BS1 BS2 BS3 BS4 BS5 BS6
Paging Paging Paging Paging Paging Paging
Agent 1 Agent 2 Agent 3 Agent 4 Agent 5 Agent 6

Paging Group 1 Paging Group 2 Paging Group 3


IEEE 802.16 Entity
CS SAP IEEE 802.16 Entity
CS SAP
Service Specific Convergence

Network Control and Management System
Radio Resource Service Specific
Sublayer

Network Control and Management System
Control and Convergence
(CS) Management Sublayer
CS Management/Configuration Functional Group (CS)
MAC SAP
MAC SAP CS Management/Configuration

M-SAP--------------C-SAP

M-SAP--------------C-SAP
Medium Access Control Functional
Group MAC CPS

MAC Common Part Sublayer
(MAC CPS)
MAC Management/Configuration
MAC Management/Configuration

Security Sublayer
Security Sublayer Management Information Base
Management Information Base
(MIB)
(MIB) PHY SAP
PHY SAP

Physical Layer
Physical Layer (PHY)
(PHY)
PHY Management/Configuration
PHY Management/Configuration
Control Plane Data Plane Management Plane
Data/Control Plane Management Plane

IEEE 802.16m reference model is very similar to IEEE 802.16-2009 standard with the exception of soft
classification of MAC common part sub-layer into radio resource control and management and medium access
control functions.

Layer 3
Network Layer

Management SAP and Control SAP

CS-SAP
System
Relay Radio Resource Location
configuration Convergence Sublayer
Functions Management management
management

Mobility Idle Mode
Multi-Carrier MBS
Management Management
Classification

Service flow and
Network-entry Security
Self Organization Connection Header
Management management
Management suppression

Radio Resource Control and Management (RRCM) MAC SAP

Layer 2
Fragmentation/Packing
Medium Access Control (MAC)
ARQ

Multi Radio Sleep Mode Scheduling and
QoS
Coexistence Management Resource Multiplexing

MAC PDU formation
PHY Control

Link Adaptation Control
Data Forwarding Interference Encryption
Ranging (CQI, HARQ, power Signaling
Management
control)

Control-Plane Data-Plane

Layer 1
PHY Protocol (FEC Coding, Signal Mapping, Modulation, MIMO processing, etc.)

Physical Layer


L3
Network Layer

Management SAP and Control SAP

Radio Resource Control and Management (RRCM) CS SAP

System Convergence Sublayer
Relay Radio Resource Location
Configuration
Functions Management Management
Management
Service Flow
Mobility Idle Mode Classification
Multi-Carrier E-MBS
Header
Service flow and Suppression
Network-entry Security
Self Organization Connection
Management

MAC SAP

Scheduling and Resource Multiplexing

L2
Fragmentation/Packing

ARQ

Multi Radio Sleep Mode
QoS
Coexistence Management

PHY Control
MAC PDU Formation
Link Adaptation Control
Data Forwarding Interference
Ranging (CQI, HARQ, power Signaling
Management
control) Encryption

HARQ/CQI
Medium Access Control (MAC) Ranging
Feedback
PHY SAP

PHY Protocol (FEC Coding, Signal Mapping, Modulation, MIMO processing, etc.)

L1
Physical Layer

Control-Plane Data-Plane
Control Primitives between MAC CPS Functions

Control Messages/Signaling (Control Plane)

Data Path (Data Plane)


IP IP
MS Packets Packets
Reports

Convergence
Convergence
Service Flow Classification Service Flow Declassification

Sublayer
Sublayer
Header Compression Header Decompression

Payload Selection and ARQ and ARQ and
Packet Segmentation Packet Reassembly

Sequencing

PDU Formation and PDU Retrieval and
Priority Handling Multiplexing De-multiplexing
Scheduling and Resource Multiplexing

Encryption Dercryption
(MAC)

Retransmission Control HARQ HARQ

Redundancy Redundancy
Version Version

Channel Coding Channel Decoding

Modulation Scheme Data Modulation Data Demodulation

PHY
PHY
MIMO Mode Selection MIMO Encoding MIMO Decoding

Resource/Power Assignment Resource Mapping Resource Demapping

Antenna Mapping Antenna Mapping Antenna Demapping

BS MS


Paging To
Available Mode Access
State
From
To
Connected State
Initialization
State
Paging
Unavailable
Mode

Power Down
Power On/Off

Normal Network Re-Entry/Fast Network Re-Entry

Initialization State
Access State* Connected State Idle State

From Access State,
Connected State, or
Idle State
Scanning and DL
Synchronization
From Initialization Sleep mode
(Preamble Detection)
State or Idle State
Ranging and UL Sleep Listening
synchronization Interval Interval

To Initialization
Broadcast Channel To Access State State Basic Capability
Acquisition Negotiation
Active Mode
Cell Selection From Access
Decision To Idle State
State
MS Authentication,
Authorization & Key
Exchange To Initialization
State
Scanning Mode

Registration with
Serving BS

To Connected
Initial Service Flow State
Establishment


Sleep Request/Sleep
Network Re-entry Process
Response Messages

Active Mode/Scanning
Connected
Idle State Mode Sleep Mode
State
(Normal Operation)

Deregistration Request/ Traffic Indication/Bandwidth
Deregistration Command Request Messages

Upon completion of initial network entry, the MS starts normal operation in the Active Mode
while periodically scanning the neighboring base stations for handover. It may transition to the
Idle State through deregistration messages or exit the Idle State and enter the Active Mode by
performing network re-entry procedures. The MS may transition to the Sleep Mode after
negotiating the sleep intervals with the serving BS and it may exit the Sleep Mode upon
receiving a traffic indication message or availability of uplink traffic.


 The convergence sublayer interfaces with network layer and MAC CPS through CS and MAC
SAPs, respectively and performs the following functions:
◦ Accepting Protocol Data Units (PDUs) from the network layer
◦ Performing classification of higher layer PDUs
◦ Processing the higher layer PDUs based on the classification (i.e., payload header compression)
◦ Delivering CS PDUs to the appropriate MAC Service Access Point (SAP)
◦ Receiving CS PDUs from the peer entity
 The Internet Protocol CS (IPCS) and Generic Packet CS (GPCS) are two types of the service
specific CS that are supported by IEEE 802.16m.
 When using GPCS, the classification is performed in protocol layers above the CS and the
relevant information for performing classification is transparently provided during connection setup
or change.
 The Asynchronous Transfer Mode CS (ATM CS) and Ethernet CS variants that were specified in
IEEE 802.16-2009 standard are no longer supported in IEEE 802.16m due to lack of industry
interest.
SFID1 CIDi1: STIDi+FID1


Network Layer
SFID3 CIDi3: STIDi+FID3 MSi
Classifier

Packets SFID4 CIDi4: STIDi+FID4


SFID6 CIDk1: STIDk+FID1

SFID7 CIDk2: STIDk+FID2 MSk
SFID8 CIDk3: STIDk+FID3
Base Station
Logical MAC Connections

Air-Interface


Six logical identifiers are defined to identify an active user and its associated connections
 Station Identifier (STID): A 12-bit STID assigned to the MS during network entry/re-entry which
uniquely identifies the MS within the coverage area of the serving BS. Each MS registered in the
network is assigned an STID.
 Temporary Station ID (TSTID): This logical identifier is used to protect the mapping between the
STID and the MS MAC address. A TSTID is assigned during initial ranging process. During
registration procedure the BS assigns and transfers an STID to the MS using encrypted
registration response message. The serving BS discards the TSTID when the MS successfully
completes the authentication procedures.
 Flow Identifier (FID): Each MS connection is assigned a 4-bit FID that uniquely identifies the
connections with the MS.
◦ The FIDs identify control and transport connections.
◦ An FID that has been assigned to one DL/UL transport connection cannot be assigned to another DL/UL
transport connection belonging to the same MS.
◦ An FID that has been used for a DL transport connection can be assigned to another UL transport connection
associated with the same MS.
 Deregistration Identifier (DID): The DID uniquely identifies an idle-mode MS for the paging
purposes.
 Context Retention Identifier (CRID): If Deregistration with Content Retention (DCR) mode is
enabled, the network assigns a 72-bit CRID to each MS during network entry or upon handover to
an IEEE 802.16m BS in a mixed-mode operation.
 E-MBS Identifier: A 12-bit value that is used along with a 4-bit FID to uniquely identify a specific E-
MBS flow in an E-MBS zone.


H E Type MSB of Header Content
T C (3 Bits) (11 Bits)

LSB of Header Content MSB of CID
(8 bits) (8 Bits)

MAC Header Payload CRC
LSB of CID Header Checksum Sequence
(8 Bits) (8 Bits)

E
H E Type MSB of Length
Header Content S CI EKS
(19 Bits) T C (6 Bits) (3 Bits)
F

LSB of Length MSB of CID
(8 bits) (8 Bits)
Bandwidth Request Bandwidth Request Uplink Transmit Power
(19 Bits) (11 Bits) (8 Bits)

LSB of CID Header Checksum Sequence
MSB LSB MSB LSB
(8 Bits) (8 Bits)
Incremental/Aggregate Bandwidth Request (BR) Bandwidth Request with Uplink Transmit Power Report

Bandwidth Request CINR Feedback Type Preferred CQI
Reserved (4 Bits)
(11 Bits) (7 Bits) (3 Bits) Period (3 Bits)
Generic MAC Header (GMH)
MSB DCD Change Indicator (1 Bit) LSB MSB FBSS Indicator (1 Bit) LSB

Bandwidth Request and Carrier to Interference plus Noise (CINR) Report Channel Quality Indicator Channel (CQICH) Allocation Request

Uplink Maximum
Preferred
Uplink Transmit Power Transmit Power Bandwidth Request Power Saving Class
DIUC Index
(8 Bits) Headroom in dB (11 Bits) (6 Bits)
(3 Bits)
(6 Bits)

MSB LSB MSB Power Class Activation (1 Bit) LSB
Reserved (1 Bit)
Reserved (1 Bit)
Physical Channel Report Bandwidth Request and Uplink Sleep Control Report

ARQ Block Serial Number/
Reserved
MAC SDU Serial Number
(8 Bits)
(11 Bits)
Signaling MAC Header
MSB LSB

ARQ Block Serial Number (BSN) or MAC SDU Serial Number (SN)


 The IEEE 802.16m specifies three types of MAC headers:
◦ Advanced Generic MAC Header (AGMH) that is used for MAC PDUs containing either MAC
management messages or user payload
◦ Short-Packet MAC Header (SPMH) that is utilized in conjunction with persistent or group
allocations
◦ Signaling MAC header
 The MAC header formats are mutually exclusive and are not used simultaneously for
the same connection.
Extended Header Type Usage

MAC SDU Fragmentation Extended Header (FEH) Fragmentation of large MAC SDUs

MAC SDU Packing Extended Header (PEH) Packing of small MAC SDUs

MAC Control Extended Header (MCEH) Transmission and fragmentation of control messages

Multiplexing Extended Header (MEH) Multiplexing of different connections on the same MAC PDU

MAC Control ACK Extended Header (MAEH) Acknowledgement of MAC control message

Piggyback Bandwidth Request Extended Header (PBREH) Piggyback bandwidth request

MAC PDU length extended header (MLEH) Extension of the size of MAC PDUs for large PDUs.

ARQ Feedback Extended Header (AFEH) ARQ feedback

Rearrangement Fragmentation and Packing Extended Header
ARQ feedback for fragmented/packed MAC PDUs
(RFPEH)

ARQ Feedback Polling Extended Header (APEH) ARQ feedback


EH
MAC PDU Length Extension
Extended Length Extended Header Group Length (4 bits)
Flow ID (4 bits) Header Length (3 bits) (3 bits)
(1 bit)
(1 bit)

Length (8 bits) Extended Header Content 1
Extended Header Type 1 (4 bits)
(Variable Length)

Advanced Generic MAC Header (AGMH) Extended Header Content 1
(Variable Length)

Extended Header Group Length
Extended
Flow ID (4 bits) Header Length (3 bits)
(1 bit) Extended Header Content 2
Extended Header Type 2 (4 bits)
(Variable Length)
Length (4 bits) Sequence Number (4 bits)

Extended Header Content 2
(Variable Length)
Short Packet MAC Header (SPMH)

Extended Header Content N
Extended Header Type N (4 bits)
(Variable Length)

Extended Header Content N
(Variable Length)

Extended Headers


MAC signaling headers are different type of headers that are used in MAC PDUs with no payload. They are
sent as standalone or concatenated with other MAC PDUs.
MAC Signaling Header Type Usage
Bandwidth Request with STID Bandwidth Request
Bandwidth Request without STID Bandwidth Request

Service Specific Scheduling Control Change or acknowledge of the scheduling or QoS parameters

Sleep Control Configuration of sleep mode operation parameters

MS Battery Level Report Terminal’s battery level reporting
Uplink Power Status Report Uplink power control status reports
Correlation Matrix Feedback Correlation matrix based precoding
MIMO Feedback MIMO feedback

Flow ID Signaling Header Type Length
(4 Bits) (5 Bits) (3 Bits)

Signaling Header Content (Size < 36 bits)


Extended FEH/PEH/ Connection
AGMH
Header(s) RFPEH/MCEH Payload

MAC PDU with Single Connection Payload

EH
Flow ID (4) = x Length (3)
(1)

Length (8)

FEH/PEH/ FEH/PEH/ Connection Connection
Extended
AGMH MEH RFPEH and RFPEH and Payload Payload
Header(s)
MCEH (flow x) MCEH (flow y) Flow ID=x Flow ID=y

NI_FI
Type (4 bits)
(4 bits)

FID (4 bits), LI (1 bit), Length (11 or 14 bits), Reserved (1 bit)

FID (4 bits), LI (1 bit), Length (11 or 14 bits), Reserved (1 bit)

EH Indicator Bitmap (Variable)

MAC PDU with Multiple Connections Payload

The MAC PDU contains a variable-sized payload. Multiple MAC SDUs and/or SDU fragments
from different unicast connections corresponding to the same MS can be multiplexed into a
single MAC PDU. The multiplexed unicast connections are associated with the same security
association.


MS BS

DL Synchronization

AAI_RNG-REQ
(MS ID* is transmitted over the air)

AAI_RNG-RSP
(TSTID is assigned by the BS)

Basic Capability Negotiation

MS Authentication and Authorization

Key Exchange

AAI_RNG-REQ
(MS ID is transmitted over the air)

AAI_RNG-RSP
(STID is assigned by the BS)

Data and Control Plane Establishment


MS Serving BS Target BS

HO-REQ

HO-RSP
BS Initiated HO
HO-CMD

HO-REQ

HO-REQ
MS Initiated HO
HO-RSP

HO-CMD

HO-IND

Network Re-entry with Target BS
Data Communication
with Serving BS
during Network Re-entry HO-COMPLT

Data Plane Re-established

In IEEE 802.16m, the handover process may be initiated by either the MS or the BS.


The IEEE 802.16-2009 standard defines four basic mechanisms for handover:
 Hard Handover (HHO):
◦ A process that is based on Received Signal Strength Indicator (RSSI)
measurements conducted on the preamble. The MS continuously measures the
RSSI of the serving BS and reports the values periodically to the serving BS. The
neighbor base stations are advertised periodically by the serving BS through a
broadcast MOB_NBR-ADV message. During the scanning period, user data is not
exchanged between the MS and the serving BS; instead the MS receives the
preambles from the each neighbor and calculates the RSSI.
 Fast Base Station Switching (FBSS):
◦ The MS and BS both maintain a list of the base stations (i.e., Diversity Set) that
are involved in FBSS operation. An Anchor BS, with which the MS only
communicates, is defined in the set. The MS may add or drop a BS to or from the
list. The Anchor BS may be changed by using HO messages or by using fast
anchor selection feedback. The measurements are based on Carrier to
Interference-plus-Noise Ratio (CINR) calculations conducted on the pilot
subcarriers in DL and UL subframes.


MS Serving BS Target BS (No 1) Target BS (No 2)

MOB_NBR-ADV

MOB_SCN-REQ

MOB_SCN-RSP

CDMA Code

Scanning Interval
Anonymous RNG-RSP
(No Data Traffic)

RNG-REQ

RNG-RSP

Scan BS No 2

MOB_SCN-REP

MOB_MSHO-REQ

MOB_BSHO-RSP

MOB_MSHO-IND

Network Re-entry with BS No 2


MS Anchor BS Target BS

MOB_NBR-ADV Receive Neighbor BS
Parameters and Compare
MOB_SCN-REQ Measured CINRs to Thresholds

MOB_SCN-RSP

CDMA Code

Anonymous RNG-RSP

RNG-REQ

RNG-RSP

MOB_MSHO-REQ

MOB_BSHO-RSP
Compare Measured
CINRs to Thresholds and
MOB_MSHO-REQ Update Diversity Set

MOB_BSHO-RSP

Update Anchor BS
MOB_MSHO-IND
to Target BS


 Macro Diversity Handover (MDHO):
◦ An MDHO process is initiated with a decision for an MS to transmit to and receive from
multiple base stations at the same time.
◦ For an MS and a BS that support MDHO, the MS and the BS maintain a list of BSs that are
involved in MDHO with the MS. The list is called the Diversity Set.
◦ Among the base stations in the Diversity Set, an Anchor BS is defined. The normal operation
where the MS is registered with a single BS is a particular case of MDHO with Diversity Set
consisting of a single BS; the Anchor BS.
◦ When operating in MDHO, the MS communicates with all base stations in the Diversity Set for
UL and DL unicast messages and traffic. There are two methods for the MS to monitor DL
control information and broadcast messages. In the first method, the MS monitors only the
Anchor BS for DL control information and broadcast messages. In the second method, the MS
monitors all the base stations in the Diversity Set for DL control information and broadcast
messages.
 Seamless Handover:
◦ In addition to optimized HHO, MS and BS may perform seamless HO, which is a variant of
HHO, to reduce HO latency and message overhead.
◦ The seamless HO is only enabled if the MS, the serving BS, and the target base stations
support seamless HO. A BS supporting seamless HO must include the connection identifier
descriptor in the system information.


MS Serving BS Target BS

HO-REQ
CID and TEK Pre-update
HO-RSP
Action
Time Seamless HO
HO-IND (BS-ID) Initiation Decline

Unicast Encrypted DL Data, UL Grant

BW-REQ, Unicast Encrypted UL Data

RNG-REQ (CMAC)

Target BS RNG-RSP (CMAC)
Becomes
Serving BS Completion of
BW-REQ (0)
Seamless HO


The HO process consists of the following stages:
 Cell Reselection: the MS may use neighbor BS information acquired from a decoded
MOB_NBR-ADV message or may request to schedule scanning intervals or sleep intervals to
scan neighbor base stations for the purpose of handover to a potential target BS.
 HO Decision and Initiation: the HO process begins with a decision for an MS to HO from a
serving BS to a target BS. The decision may originate either at the MS or at the serving BS.
 Downlink Synchronization: the MS synchronizes to the DL transmissions of the target BS and
obtains system configuration information.
 Ranging: the MS and target BS must perform initial ranging or HO ranging. If the RNG-REQ
message includes the serving BS-ID, then the target BS may request the serving BS to provide
the MS information over the backhaul. The normal network re-entry process may be simplified by
target BS possession of MS information.
 Termination of MS Context: the final step in HO is termination of MS context that is defined as
serving BS termination of context of all connections belonging to the MS and the context
associated with them (i.e., information in queues, ARQ state machine, counters, timers, header
suppression information, etc., is discarded).
 HO Cancellation: an MS may cancel HO via MOB_HO-IND message at any time prior to
expiration of Resource_Retain_Timer after transmission of MOB_MSHO-REQ (in case of MS-
initiated HO) or MOB_BSHO-REQ (in case of BS-initiated HO).


Select Alternative Target
Initiate Cell Selection
BS

DL Synchronization and New DL Synchronization
System Information and System Information
Acquisition Acquisition
(DL/UL Parameters) (New DL/UL Parameters)

Cell Rejected Cell Rejected

Ranging and UL Ranging and UL
Synchronization Synchronization
Cell Rejected Cell Rejected

Basic Capability Negotiation MS Re-authorization

Cell Rejected

MS Authorization and Key
Re-registration and
Exchange
Cell Rejected

Reestablishment of Service
Registration with BS
Flows

IP Connection IP Connection
Normal Operation
Establishment Reestablishment

Operations with the Base Station

Transfer of Operational
Parameters

HO Execution
Connection Establishment

Cell Reselection
Scanning Intervals
for Detecting and Normal Operation
Evaluating Neighbor
Cells

HO Decision


MS Serving BS Target BS MS Serving BS Target BS

AAI_HO-REQ AAI_HO-REQ

AAI_HO-CMD AAI_HO-CMD
Action Time

Action Time
AAI_HO-IND AAI_HO-IND

HO Ranging Initiation Deadline

HO Ranging Initiation Deadline
(Dedicated) CDMA Ranging Code (Dedicated) CDMA Ranging Code

Disconnect Time
AAI_RNG-ACK AAI_RNG-ACK

Maintain Data Communication
Unicast Encrypted DL Data/UL Grant with the Serving BS during
Network Re-entry

Unicast Encrypted UL Data/Bandwidth Request

AAI_RNG-REQ (CMAC) AAI_RNG-REQ (CMAC)

AAI_RNG-RSP (CMAC) AAI_RNG-RSP (CMAC)

Completion of Network Re-entry and HO Completion of Network Re-entry and HO

Network Re-entry Procedures when Entry-Before-Break Disabled Network Re-entry Procedures when Entry-Before-Break Enabled


 For handover from a new serving to a legacy target BS, the legacy MS detaches from the legacy
zone of the serving BS to the target BS using legacy handover signaling and procedures.
 For handover from a new BS to a legacy BS, the new MS detaches from the serving BS and
performs handover procedures specified by IEEE 802.16m. The MS performs network re-entry
with target legacy BS using network re-entry procedures specified in IEEE 802.16-2009 standard.
 An MS performs handover from a legacy BS to a new BS by using either zone-switching or direct
handover process.
◦ The zone-switching handover is applicable to new base stations supporting coexisting legacy and new system.
◦ The direct handover is applicable to new base stations which only support new mobile stations. A new BS may
also decide to keep a new MS in the legacy zone when coexist-ing with legacy systems.
Serving Serving
MS Target New BS MS Target New BS
Legacy BS Legacy BS

LZone MZone LZone MZone

MOB_MSHO-REQ MOB_MSHO-REQ

MOB_BSHO-RSP MOB_BSHO-RSP

MOB_HO-IND MOB_HO-IND
(Target BS-ID) (Target BS-ID)

RNG-REQ RNG-REQ

RNG-RSP RNG-RSP

RNG-RSP (including Zone-Switching Parameter) Data Path Established

Synchronization with MZone RNG-RSP (including Zone-Switching Parameter)

AAI_RNG-REQ
Synchronization with MZone
Ranging Purpose Indication = Zone Switch

AAI_RNG-REQ
AAI_RNG-RSP
Ranging Purpose Indication = Zone Switch

Data Path Established AAI_RNG-RSP

Data Path Established

The Target BS Instructs the MS to Switch Zone during Network Re-entry The Target BS Instructs the MS to Switch Zone after Network Re-entry


Delay Bit Error Rate
Service Class Categories Bit Rate Use Cases
Requirement (BER) Margin
Tele-presence/Video-conference,
Point to Multi-Point, Multi-Point to
Collaborative work Navigation systems,
Multi-Point, Multi-Point to Point, < 20 ms 1 - 20 Mbps 10-9 ≤ BER ≤ 10-6
Real-time Gaming, Real-time video
Highly Interactive
streaming
Asymmetric, Interactive, Low Remote Control Sensors, Interactive
20 – 100 ms 8 - 512 kbps 10-9 ≤ BER ≤ 10-6
Rate geographical maps
Point to Multi-Point, Multi-Point to Rich data call, Video
Multi-Point, Multi-Point to Point, 20 – 100 ms 1- 50 Mbps 10-6 ≤ BER ≤ 10-3 broadcasting/streaming, High quality video
Interactive, High Rate conference, Collaborative work
Voice telephony, Instant messages,
Multiplayer gaming, Audio streaming, Video
Conversational, Soft BER 100 - 200 ms 8 - 512 kbps BER ≤ 10-3
telephony (medium quality) Multiplayer
gaming (high quality)

Conversational, Symmetric QoS, High quality video telephony, Collaborative
100 - 200 ms 1 - 50 Mbps 10-6 ≤ BER ≤ 10-3
Tight BER work, Access to databases, file systems

Messaging (data/voice/media),
Point to Point Unidirectional Web browsing, Audio on demand, Internet
8 kbps – 50
(Uplink or Downlink), > 200 ms 10-9 ≤ BER ≤ 10-6 radio, Access to databases, Video
Mbps
Asymmetric, Delay Tolerant download/upload, Peer-to-peer file sharing,
Video streaming


 There are three types of service flows as follows:
◦ Provisioned: This type of service flow is provisioned by the network management
system and its AdmittedQoSParamSet and ActiveQoSParamSet attributes are
both null.
◦ Admitted: This type of service flow has resources reserved by the BS for its
AdmittedQoSParamSet, but these parameters are not active (i.e., its
ActiveQoSParamSet is null). The admitted service flows may be provisioned by
other mechanisms in the network.
◦ Active: This type of service flow has resources committed by the BS and its
ActiveQoSParamSet attribute is non-empty.

AuthorizedQoSParamSet
(BS only)

AdmittedQoSParamSet
(SFID and CID)

ProvisionedQoSParamSet
(SFID)
ActiveQoSParamSet
(SFID and Active CID)

Relationship between the QoS Parameter Sets

 Uplink/Downlink Indicator parameter identifies service flow direction relative to the originating
entity.
 Maximum Sustained Traffic Rate is a parameter that defines the peak information rate of the
service. The rate is expressed in bits per second and pertains to the service data units at the input
to the system. This parameter does not limit the instantaneous rate of the service since this is
governed by the physical attributes of the entrance port.
 Maximum Traffic Burst parameter defines the maximum burst size that is accommodated for the
service. Since the physical rate of input/output ports, any air-interface, and the backhaul will in
general be greater than the maximum sustained traffic rate parameter for a service, this
parameter describes the maximum continuous burst the system should accommodate for the
service assuming the service is not currently using any of its available resources.
 Minimum Reserved Traffic Rate parameter specifies the minimum rate, in bits per second,
reserved for this service flow. The BS is required to satisfy the bandwidth requests for a
connection up to its minimum reserved traffic rate The value of this parameter excludes the MAC
overhead.
 Maximum Latency is a parameter, whose value specifies the maximum interval between
reception of a packet at the convergence sublayer of the BS or MS and the transmission of the
corresponding physical layer PDU over the air-interface. A value of zero for maximum latency is
interpreted as no commitment.
 SDU Indicator is a parameter whose value specifies whether the SDUs are fixed or variable
length.


 Paging Preference is a single bit indicator of a mobile station’s preference for the reception of
paging advisory messages during the Idle State. It indicates that the BS may present paging
advisory messages or other indicators to the MS, when there are MAC SDUs bound for an idle
mode MS.
 Uplink Grant Scheduling Type specifies which uplink grant scheduling service type is
associated with uplink service flow. This parameter is present in the uplink direction.
 Tolerated Jitter is a parameter whose value specifies the maximum delay variation (jitter) for the
connection. This parameter is present for a DL or UL service flow, which are associated with
Uplink Grant Scheduling Type = UGS or ertPS.
 Request/Transmission Policy is a parameter whose value specifies certain attributes for the
associated service flow.
 Traffic Priority is a parameter whose value specifies the priority of associated service flow. This
parameter is present for a DL or UL service flow, which are associated with any Uplink Grant
Scheduling Types except UGS.
 Unsolicited Grant Interval parameter defines the nominal interval between successive data
grant opportunities for a DL service flow, which are associated with Uplink Grant Scheduling Type
= UGS or ertPS.
 Unsolicited Polling Intervals parameter defines the maximum nominal interval between
successive polling grants opportunities for a UL service flow, which are associated with Uplink
Grant Scheduling Type = rtPS.


 Unsolicited Grant Service (UGS) is designed to support real-time uplink service flows that
transport periodic fixed-size data packets such as VoIP without silence suppression. This service
class provides fixed-size grants on a real-time periodic basis, which eliminates the overhead and
latency due to MS bandwidth requests and ensures timely availability of the grants to meet the
real-time characteristics of the service flow.
 Real-Time Polling Service (rtPS) is designed to support real-time UL service flows that transport
variable-size data packets on a periodic basis such as MPEG video format. This service offers
real-time, periodic, and unicast request opportunities, which meet the service flow’s real-time
requirements and further allow the MS to specify the size of the desired grant. This service
involves more overhead than UGS, but supports variable-sized grants for optimal data transport.
 Extended Real-Time Polling Service (ertPS) is a scheduling mechanism which utilizes the
advantages of UGS and rtPS. The BS provides unicast grants in an unsolicited manner similar to
UGS, reducing the latency of bandwidth request. Unlike the UGS allocations, the ertPS
allocations are variable-sized.
 Non-Real-Time Polling Service (nrtPS) offers unicast polls on a regular basis, which ensures
that the UL service flow receives request opportunities even during network congestion. The
serving BS typically polls nrtPS connections every one second and provides timely unicast
request opportunities.
 Best Effort (BE) service is designed to support applications for which no minimum service
guarantees (e.g., no rate or delay requirements) are required. The MS is allowed to use
contention-based and unicast request opportunities for data transmission.


 In addition to the legacy service class attributes, IEEE 802.16m defines a new service class
attribute called Maximum Sustained Traffic Rate per Flow.
 The new attribute defines the peak information rate of the service flow. The maximum rate is
denoted in bits per second and pertains to the service data units at the input of the convergence
sublayer.
 This parameter does not include transport, protocol, or network overhead information and does
not limit the instantaneous rate of the service flow since this is governed by the physical attributes
of the ingress port. However, at the destination network interface in the uplink direction, the
service is regulated to ensure conformance to this parameter. The time interval over which that
the traffic rate is averaged is defined during service negotiation. In the downlink direction, it may
be assumed that the service was already regulated at the ingress to the network. If this parameter
is set to zero, then there is no explicitly mandated maximum rate. The maximum sustained traffic
rate field specifies only a bound, not a guarantee that the rate is available.
 Adaptive Grant and Polling Service (aGPS) is a new service class defined in IEEE 802.16m
where the BS may grant or poll an MS periodically and may negotiate only primary QoS
parameters or both primary and secondary QoS parameter sets with the MS.
◦ Initially, the BS uses QoS parameters defined in the primary QoS parameter set including primary Grant and
Polling Interval (GPI) and primary Grant Size. During the service, the traffic characteristics and QoS
requirement may change.
◦ Adaptation includes switching between primary and secondary QoS parameter sets or changing of GPI/Grant
size to values other than those defined in the primary or second-ary QoS parameter sets when the traffic can
be characterized by more than two QoS states.


QoS Class Applications QoS Parameters
UGS Maximum sustained rate, Maximum latency tolerance, Jitter
VoIP
Un-Solicited Grant Service tolerance
rtPS Minimum Reserved Rate, Maximum Sustained Rate,
Streaming Audio, Video
Real-Time Packet Service Maximum Latency Tolerance, Traffic Priority
ErtPS
Voice with Activity Minimum Reserved Rate, Maximum Sustained Rate,
Extended Real-Time Detection (VoIP) Maximum Latency Tolerance, Jitter Tolerance, Traffic Priority
Packet Service
nrtPS
Minimum Reserved Rate, Maximum Sustained Rate, Traffic
Non-Real-Time Packet FTP
Priority
Service
BE Data Transfer, Web
Maximum Sustained Rate, Traffic Priority
Best-Effort Service Browsing
aGPS
Maximum Sustained Traffic Rate, the Request/Transmission
Adaptive Granting and Application Agnostic
Policy, Primary Grant and Polling Interval, Primary Grant Size
Polling


An Overview of IEEE 802.16m Radio Access Technology Globecom 2010

An Overview of IEEE 802.16m Radio Access Technology Globecom 2010

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