IEEE C802.16ppc-10/0044
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Contribution for Hierarchical Network Study Report
Date
Submitted
2010-07-12
Source(s)
Ronny Yongho Kim
Jin Lee
Giwon Park
Inuk Jung
Kyujin Park
Hankyu Cho
Eunjong Lee
Youngsoo Yuk
Jin Sam Kwak
E-mail: ronnyyongho.kim@lge.com
jin1.lee@lge.com
giwon.park@lge.com
inuk.jung@lge.com
kyujin.park@lge.com
hg.cho@lge.com
eunjong.lee@lge.com
youngsoo.yuk@lge.com
jinsam.kwak@lge.com
LG Electronics
Re:
Call for contributions for the 802.16 Project Planning Committee meeting
Abstract
This document proposes materials for Hierarchical network study report
Purpose
To be discussed and adopted by 802.16 PPC
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.
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<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>.
Contribution for Hierarchical Network Study Report
1
Usage cases in Multi-RAT Networks ..............................................................................3
1.1
WiFi integrated Femtocell BS (Wi-Femto) .........................................................3
1.2
Mobile with WiFi Client Cooperation Function (Wi-CC)...................................3
1.3
Multi-RAT Aggregation (Wi-AGG) ....................................................................4
2
Multi-RAT Architecture ..................................................................................................6
2.1
Protocol Architecture ...........................................................................................6
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2.2
Multi-RAT System Architecture ..........................................................................7
3
Features for Multi-RAT ...................................................................................................7
3.1
Interworking of Multiple Radio Access Technologies ........................................7
3.2
Off-Load...............................................................................................................8
4
Requirements for Multi-RAT ..........................................................................................8
5
Multi-tier Network ...........................................................................................................8
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1 Usage cases in Multi-RAT Networks
Multi-RAT capable IEEE 802.16 devices can be divided into three depending on usage cases:
1. WiFi integrated Femtocell BS, denoted as Wi-Femto
2. IEEE 802.16 mobile with WiFi Client cooperation function, denoted as Wi-CC
3. Mobile device with multi-RAT aggregation function, denoted as Wi-AGG
1.1 WiFi integrated Femtocell BS (Wi-Femto)
Wi-Femto is a dual RAT BS device with IEEE 802.16 femtocell BS and IEEE 802.11 AP functionalities. WiFemto is connected to fixed broadband connection (e.g., DSL, cable, fibler, etc.) like femtocell BS or AP. IEEE
802.11 link of Wi-Femto can work as a virtual IEEE 802.16 link which provides additional bandwidth. An
example deployment model of Wi-Femto is shown in Fig. 1. Depending on the communication conditions
between Wi-Femto and mobiles, either IEEE 802.11 link or IEEE 802.16 link can be used. Two of usage models
of Wi-Femto are traffic offloading and interference mitigation.
1. Traffic offloading: When the traffic load of Wi-Femto is increased, some of the traffic can be offloaded
using IEEE 802.11 link.
2. Interference Mitigation: There might be interference problem, due to dense deployment of Femtocell
BSs. If a femtocell BS makes or experiences severe interference to/from other femtocell BSs,
interference can be mitigated by allocating IEEE 802.11 link to users.
Internet
(ISP)
Wi-Femto
IEEE 802.16
mobile
IEEE 802.11 link
IEEE 802.16 link
Wi-CC Mobile
Fixed Broadband
Connection
Wi-CC Mobile
Figure 1. Example deployment model of Wi-Femto
1.2 Mobile with WiFi Client Cooperation Function (Wi-CC)
Wi-CC is a dual RAT mobile device with IEEE 802.16 mobile and IEEE 802.11 functionalities. Wi-CC is able
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IEEE C802.16ppc-10/0044
to communicate with IEEE 802.16 BS while communicating with other Wi-CC using IEEE 802.11. When both
a direct IEEE 802.16 link to the IEEE 802.16 BS and indirect IEEE 802.11 link via other Wi-CC to the IEEE
802.16 BS are available to a Wi-CC, it can choose one of them depending on link quality or use both links to
communicate with the IEEE 802.16x BS.
IEEE 802.16x BS
Wi-CC
(Relay function)
IEEE 802.11 link
IEEE 802.16 link
Wi-CC
(Mobile function)
Wi-CC
(Mobile function)
Figure 2. Example deployment model of Wi-CC
1.3 Multi-RAT Aggregation (Wi-AGG)
For the purpose of off-loading, operators can deploy several IEEE802.11 APs at busy area inside of the
IEEE802.16x coverage.
In this scenario, the AMS is capable of communicating IEEE 802.11 APs while it maintains its connection to
the IEEE802.16x network. Since the IEEE802.16x network covers the AP’s coverage, the AMS can always be
connected to the IEEE802.16x ABS and it can communicate with an IEEE802.11 AP when it is entered to the
AP’s coverage.
As a primary connection, AMS is always connecting to IEEE 802.16x network which provides control plane
services such as mobility, paging, authentication etc as well as IP-based traffic services to an AMS.
In addition to the primary connection, ABS forwards a specific data traffic of the AMS to the IEEE802.11
connection based on the ABS’s load condition and required QoS level of the flow.
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IEEE C802.16ppc-10/0044
Internet
(ISP)
Control
Connection
IEEE 802.16x BS
IEEE 802.11 AP
IEEE 802.11 link
IEEE 802.16 link
Wi-AGG
Figure 3. Example deployment model of Wi-AGG
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IEEE C802.16ppc-10/0044
2 Multi-RAT Architecture
2.1 Protocol Architecture
Generic Link Layer (GLL)
MAC SAP
PHY
MLME
PLCP Sublayer
PHY Sublayer
Management
Entity
Physical Layer
(PHY)
PMD SAP
Physical Layer
C-SAP
PHY SAP
MAC Sublayer
PHY SAP
PLME
MAC Common
Part Sublayer
(MAC CPS)
Station Management Entity
M-SAP
MAC
MAC SAP
Network Control and Management System
MAC Sublayer
Management
Entity
Service Specific
Convergence
Sublayer (CS)
Data Link Layer
CS SAP
PMD Sublayer
IEEE 802.16x
IEEE 802.11
Figure 4. Protocol architecture of Multi-RAT devices
Example protocol architecture of Multi-RAT devices is shown in Fig. 3. Protocol structure provides automatic
way of data PDU transfer from one radio and to another radio. Generic link layer (GLL) is an intermediary layer
between IP layer and MAC layer. The functions of GLL are: data relay between radios, link control, multi-RAT
co-ordination, etc.
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IEEE C802.16ppc-10/0044
2.2 Multi-RAT System Architecture
802.16
PHY/MAC
Wi-Fi
AP
802.11
PHY/MAC
Femto
ABS
GLL
GLL
802.16x AMS
Femto
GW
GLL
802.16x AMS
GLL
802.16x AMS
802.16
PHY/MAC
802.16
PHY/MAC
Internet
ASN
802.11
PHY/MAC
ABS
802.11
PHY/MAC
GLL
GLL
CSN
802.11
PHY/MAC
ASN GW
(FA/MAG)
802.16
PHY/MAC
AAA
HA/LMA
802.16x AMS
ABS
GLL
GLL
802.16x AMS
802.16
PHY/MAC
802.11
PHY/MAC
AP
AP
AP
WLAN
Access
GW
WiFi Access Network
Figure 5. System architecture of Multi-RAT deployment
Example of system architecture of Multi-RAT network for various usage scenarios is shown in Fig. 5. The
WiFi-WiMAX interworking model being studied in WiMAX forum is shown as a reference deployment mode.
3 Features for Multi-RAT
3.1 Interworking of Multiple Radio Access Technologies
Interworking of Multiple Radio Access Technologies implies that Multi- RAT mobile devices communicate
with other RAT systems or other RAT devices. This feature is required for Multi-RAT devices, e.g., mobile
with WiFi Client Cooperation Function (Wi-CC). The 802.16 system shall provide control & management of
multiple RATs and enhance connectivity and cooperation for multi-radio devices.
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3.2 Off-Load
Off-Load implies that the traffic is offloaded using other RAT link. This feature can be required for Multi-RAT
devices when the traffic load of current RAT’s link is increased. The use case model that requires this feature is
WiFi Off-Load (e.g., when the traffic load of a dual RAT BS device with IEEE 802.16 femtocell BS and IEEE
802.11 AP functionalities is increased, some of the traffic can be offloaded using IEEE 802.11 link).
4 Requirements for Multi-RAT
 IEEE 802.16 device supporting multi-RAT function, e.g., Wi-Femto and Wi-CC devices, shall support
one or more radio access technologies (e.g., IEEE 802.11, 802.16)
 An IEEE 802.16 device supporting multi-RAT function should be able to communicate with another
IEEE 802.16 devices supporting multi-RAT function through IEEE 802.11 radio access technology.
 IEEE 802.16 devices supporting multi-RAT function shall be able to switch its radio access
technologies based on a certain condition.
 Connection of an IEEE 802.16 device supporting multi-RAT function with a IEEE 802.16 BS shall be
continuously supported when the IEEE 802.16 device communicates with the IEEE 802.16 BS using
other RAT link via a cooperating IEEE 802.16 device supporting multi-RAT function.
 An IEEE 802.16 device supporting multi-RAT function shall be able to be connected to one or more
radio access technologies of other IEEE 802.16 device supporting multi-RAT function.
 IEEE 802.16 devices supporting multi-RAT function should scan and report its channel status
periodically on each radio access technology.
 IEEE 802.16 devices supporting multi-RAT function shall be able to discover its neighbor IEEE 802.16
devices supporting multi-RAT function.
 IEEE 802.16 devices supporting multi-RAT function should be able to transmit the data packet received
from neighbor IEEE 802.16 devices supporting multi-RAT function to IEEE 802.16 BS.
 IEEE 802.16 devices supporting multi-RAT function should be able to transmit the data packet received
from ABS to its neighbor IEEE 802.16 devices supporting multi-RAT function.
 Data PDU shall be formatted to automatically transferred from one radio to other radio within IEEE
802.16 devices supporting multi-RAT function.
 IEEE 802.16 devices supporting multi-RAT function shall be able to perform handover between
IEEE802.16 BS and IEEE802.11 AP.
 IEEE 802.16 devices supporting multi-RAT function shall be able to enable its IEEE802.16 radio
interface by input of its IEEE802.11 protocol and vice versa.
5 Multi-tier Network
Representative multi-tier functions are Femto and Relay. The difference between them is that Relay requires
wireless backhauling between macro BS and relay station (RS) while Femto does not. Since details on Femto
and Relay have been discussed in IEEE 802.16m, it would be first to check if we need to newly discuss about
Relay and Femto in this new project.
One new multi-tier function which has not been discussed is In-band client cooperation (CC). Details are shown
in the following subsection.
2.1 In-band Client cooperation (In-band CC)
As shown in Fig. 6, client cooperation is a function which enables relay through mobile device or cooperative
data transmission by cooperative devices to achieve throughput enhancement, reduced device power
consumption, and interference reduction to neighbor cell. In-band CC means that the communication between
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IEEE C802.16ppc-10/0044
cooperative devices is performed in-band. In other words, the same radio access technology as macro-cell is
used for communication link between cooperative devices. If WirelessMAN-Advanced Air Interface is used for
in-band CC, then, client cooperation can be exploited between distant devices (e.g., widely spread M2M devices
belonging to the same service provider). Moreover, it is possible to efficiently control communication link
between cooperative devices since all the communication links are based on the same radio access technology
which is controllable in macro BS side.
CC (In-band)
Macro
Cooperative
transmission
Mobile relay
WirelessMAN Advanced Air Interface
Figure 6. In-band CC using WirelessMAN Advanced Air Interface
9