IEEE C802.16m-07/287r1
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Proposal for System Reference Architecture of Supporting Femto Cell Operations in
IEEE 802.16m
Date
Submitted
2007-11-11
Source(s)
Ting-Chen (Tom) Song, Chi-Fang (Richard) Li, Fang-Ching
tomtom@itri.org.tw
(Frank) Ren, Chun-Yen Wang (Bibo),Tzu-Ming (Brain) Lin,
richard929@itri.org.tw
Ren-Jr Chen,, Chie-Ming Chou, ITRI
Wern-Ho Sheen, NCTU/ITRI
Re:
IEEE 802.16m-07/040 - Responds to Call for Contributions on Project 802.16m System
Description Document (SDD)
Abstract
This contribution proposes the System Reference Architecture for supporting Femto
Cell Operations in Draft IEEE 802.16m System Description Document.
Purpose
Response to call for Reference Architecture regarding to Project 802.16m SDD
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.
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Further
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Proposal for System Reference Architecture for Supporting Femto Cell Operations in
IEEE 802.16m
Ting-Chen (Tom) Song, Chi-Fang (Richard) Li, Fang-Ching (Frank) Ren, Chun-Yen Wang,
Tzu-Ming (Brain) Lin, Ren-Jr Chen, Chie-Ming Chou, ITRI
Wern-Ho Sheen, NCTU/ITRI
1. Summary
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Since most voice and high-bandwidth data-usage services occur indoors, the deployment of Fixed-Mobile
Convergence (FMC) solution [1] in IEEE 802.16m will expand the licensed spectrum of operators with
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wireless broadband link in-house. FMC can further improve Quality of Service (QoS) and the reliability
indoors, expand macro networks and coverage, and increase ARPU. Despite the number of challenges,
which were addressed in the 3GPP2 Femto Cell Workshop, need to be solved and overcome with, all in all,
the deployment of the FMC solution within IEEE 802.16m architecture will provide a complete solution of
meeting the IMT-Advanced performance requirements by enhancing the data rate indoors and support data
rates up to approximately 1Gbit/s for stationary or low mobility and 100 Mbit/s for high-mobility [2].
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The aim of this contribution is to propose Femto Cell reference architecture for the IEEE 802.16m SDD in
order to facilitate and meet the Femto Cell operations; firstly, to adopt the text proposed that addresses the
radio interference issues of deploying Femto Cell and proposed its layout as a basic TOC of the SDD;
including the Femto Cells architecture, mobility management issue, access control and measurement issues.
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Secondly, to adopt the proposed reference network architecture that supports IEEE 802.16m Femto cell
operations.
Access Service Network Gateway(ASN-GW)
Internet
Base Station(BS)
Wireless access link
Wired link
Connectivity Service
Network(CSN)
Connectivity Service
Network(CSN)
ASN
R3
MCID 1
BS
ASN-GW
MCID 1
R4
BS
2
MCID
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ASN-GW
BS
Figure 1: Legacy 802.16 reference network model
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Reference Network Architecture
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A general view of 16m reference network architecture to support Femto Cells operations will describe below.
Figure 1 illustrates the legacy network architecture of IEEE802.16 standard [2]. It comprises of three major
functional aggregations: Mobile Station (MS), Access Service Network (ASN) and Connectivity Service
Network (CSN). The ASN is a collection of functions described as Base Station and ASN Gateway
(ASN-GW), which can be rendered in one or more ASN configurations. The CSN comprises network
elements such as, user databases, AAA proxy/servers and MIP HA.
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R3 interface consists of a set of control plane protocols between the ASN and CSN to support AAA policy
enforcement and mobility management capabilities. This also encompasses the bearer plane methods to
transfer data between ASN and CSN.R4 interface consists of set of Control and Bearer plane protocols that
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co-ordinate UE mobility between ASNs. R4 encompasses the following functionality relating to mobility
management:
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Handover Control and Anchoring: These functions control overall handover decision making and
signaling procedures related to handovers.
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Context Transfer: These functions help with the transfer of any state information between network
elements.
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
Bearer Path setup: These functions manage the data path setup and include procedures for data
packet transmission between functional entities.
Access Service Network
Gateway(ASN-GW)
Indoor :
Femto Cell
Subscriber’s
Broadband
Circuit
Base Station(BS)
Wireless access link
Femto Cell AP
Wired link
Connectivity Service
Same Handset
Network(CSN)
available both
indoor and
outdoor
Femto Cell BS
Femto Network
Gateway (FNG)
R5
Internet or
IP Based Network
Femto Network
Gateway (FNG)
Connectivity Service
Network(CSN)
ASN
MCID 1
R3
BS
ASN-GW
MCID 1
R4
BS
2
MCID
ASN-GW
BS
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Figure 2: Enhanced reference network Architecture for IEEE 802.16m Femto cell operations.
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2. Proposal 1: Reference Network Architecture for the IEEE 802.16m Femto cell
operations
The concept of Femto cell is illustrated in Figure 2: A plug-and-play low power Femto Cells Base Station
(BS) transceiver is installed indoors (home or office), and connected to the internet via cable, DSL, or a
similar IP backhaul technology. This connection is used to integrate the Femto cell with the WAN wireless
operator’s core network via an apparatus called Femto Network Gateway (FNG).
For supporting Femto Cell operations, the Femto Network Gateway (FNG) system shall:
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ensure the security connection between the operator’s core network and Femto cells,
aggregate signaling from multiple Femto cells to reduce number of interfaces to macro network,
minimize Femto cell design by perform as a Foreign agent to the Femto cells, e.g. Access control and
measurement, Mobility management and Hand over procedures.
IEEE 802.16m network components consist of base stations (BSs), Access Service Network Gateway
(ASN-GW), Femto Network Gateway (FNG), Femto Cell BS and mobile stations (MSs). BSs constitute the
radio interface between radio access and fixed network systems, and are under the control of ASN gateway
through R4 interfaces. Femto cells AP transceiver constitute the radio interface between radio access and IP
based system, and are under the control of FN Gateway through IP based interfaces. In general, FNGs and
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BSs are responsible for cell selection, radio resource management, mobility management, access and
measurement control…etc.
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3. Proposal 2: The SDD Table of Content (TOC) relating to Femto Cell Operations
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X.1 Femto Cell Architecture and Operations
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X.2 Mobility Management in Femto Cells_IDLE
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X.3 Mobility Management in Femto Cells_ACTIVE
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X.3.1
Hand over (HO) decision and initiation
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X.3.2.
Forward Link (Macro to Femto)
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X.3.3.
Reverse Link (Femto to Macro)
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X.4 Access Control and Measurements
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X.4.1.
Neighbor Femto measurement
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X.4.2.
Neighbor Macro measurement
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Conclusion
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In this contribution, a Femto Cell reference architecture is proposed for IEEE 802/16m in order to facilitate
and meet the Femto Cell requirements. Radio Interference issues of deploying Femto Cell are discussed and
formed as a basic layout of the SDD Table of Content. It is proposed to capture the reference operation and
architecture into the IEEE 802.16m system description document (SDD).
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[1]
[2]
[3]
[4]
References
3GPP2 Femto Cell Workshop, www.3gpp2.org/FEMTO
IEEE802.16m-07/002r3 “Draft IEEE 802.16m Requirements”
P802.16Rev2/D0d “Part 16: Air Interface for Broadcast Wireless Access Systems”
P802.21D06 “Draft Standard for Local and Metropolitan Area Networks: Media Independent Handover
Services”
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Proposed Text
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-----------------------------Begin Proposed Text ----------------------------------------------------------------------
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The following text is proposed to be adopted as TOC for Femto Cell Operations in 802.16m SDD.
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Femto Cells Function Architecture
X.1 Femto Cells Architecture and Operations
This section describes legacy network model and 802.16m’s Femto Cell Operations reference architecture.
A new entity Femto Network Gateway (FNG) and a new interface (R5) are introduced in order to support
and meet Femto cell operations.
Access Service Network
Gateway(ASN-GW)
Indoor :
Femto Cell
Subscriber’s
Broadband
Circuit
Base Station(BS)
Wireless access link
Femto Cell AP
Wired link
Connectivity Service
Same Handset
Network(CSN)
available both
indoor and
outdoor
Femto Cell AP
Femto Network
Gateway (FNG)
R5
Internet or
IP Based Network
Femto Network
Gateway (FNG)
Connectivity Service
Network(CSN)
ASN
MCID 1
R3
BS
ASN-GW
MCID 1
R4
BS
2
MCID
ASN-GW
BS
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Figure X: Enhanced reference network Architecture for IEEE 802.16m Femto cell operations.
A plug-and-play low power Femto Cells Access Point (AP) transceiver is installed indoors (home or office),
and connected to the internet via cable, DSL, or a similar IP backhaul technology. This connection is used to
integrate the Femto cell with the WAN wireless operator’s core network via an apparatus called Femto
Network Gateway (FNG).
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For supporting Femto Cell operations, the Femto Network Gateway (FNG) system shall:
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ensure the security connection between the operator’s core network and Femto cells,
aggregate signaling from multiple Femto cells to reduce number of interfaces to macro network,
minimize Femto cell design by perform as a Foreign agent to the Femto cells, e.g. Access control and
measurement, Mobility management and Hand over procedures.
provide MSs roaming facility between BSs and Femto cell BSs .
X.2 Mobility Management in Femto Cells_IDLE
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Femto Cell shall only allow specific MS and/or a family of MSs to access its network. A Femto Cell shall
remain idle when no specific MSs is detected in order to save power and reduce interference. Any
non-members entering Femto Cell zone will prohibited to access such Femto Cell BS.
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In this case, MS identifier and Femto cell BS identifier shall be broadcast over the air. The MSs shall store
the identifiers of the Femto Cell which is allowed to access for the MSs.
X.3 Mobility Management in Femto Cells_ACTIVE
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In order to support mobility from Macro BS to Femto cell BS and maintain service continuity, the following
functionalities are necessary:
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Network topology acquisition: BSs shall be able to provide information regarding to network topology
and schedule appropriate scanning period for MSs to acquire Femto Cell BS condition.
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Both BSs and MSs are able to trigger Forward and Backward Handover process. Handover procedure
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shall consist of HO decision and initiation, PHY layer re-synchronization, network re-entry and
connection re-setup.
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X.3.1
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Hand over (HO) decision and initiation
MSs and Femto Cell BS shall initiate the scanning process. Femto cell BSs could schedule and allocate
time intervals for MSs to scan Femto cell BS’s signal. According to the number of receivers in MSs,
allocation of scanning interval can be categorized into single-receiver and multi-receiver MS scanning.
The reporting scanning results can be either periodic or event-triggered.
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Once handover is initiated, MSs will synchronize with Femto BSs and perform authorization and
register to setup its connection.
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X.3.2.
Forward Link (Macro to Femto)
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MS handover from Macro to Femto cells can be used in a number of situations. For instance:
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If higher QoS needs to be preserved
When an MS enter the Femto cell BS zone, Forward Link HO is necessary to maintain its connectivity.
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X.3.3.
Reverse Link (Femto to Macro)
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MS handover from Femto BSs to Macro BSs can be used in a number of situations. For instance:
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When an MS leaves the Femto cell BS zone, Reverse Link HO is necessary to maintain its
connectivity.
X.4 Access Control and Measurements
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X.4.1.
Neighbor Femto measurement
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X.4.2.
Neighbor Macro measurement
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---------------------------End of Text Proposal ---------------------------------------------------------------------
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