eRAN
WTTx Overview Feature Parameter
Description
Issue
01
Date
2022-03-08
HUAWEI TECHNOLOGIES CO., LTD.
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WTTx Overview Feature Parameter Description
Contents
Contents
1 Change History.........................................................................................................................1
1.1 eRAN18.1 01 (2022-03-08)..................................................................................................................................................1
1.2 eRAN18.1 Draft A (2021-12-30)........................................................................................................................................ 1
2 About This Document.............................................................................................................2
3 Introduction.............................................................................................................................. 3
4 Application Scenarios............................................................................................................. 5
4.1 Households................................................................................................................................................................................ 5
4.1.1 Video Service......................................................................................................................................................................... 5
4.1.2 VoIP Service............................................................................................................................................................................ 6
4.2 Enterprises................................................................................................................................................................................. 9
4.2.1 Voice Service Solution........................................................................................................................................................ 9
4.2.2 VPN Private Line Service Solution............................................................................................................................... 11
4.2.3 ODU Management and Enhancement...................................................................................................................... 12
4.3 WTTx Community Scenario............................................................................................................................................... 13
4.3.1 Operator-ISP Coordination Solution........................................................................................................................... 13
4.3.2 Fixed Mobile Convergence Solution............................................................................................................................ 14
5 Differences Between WTTx and MBB Networks............................................................15
5.1 Site............................................................................................................................................................................................. 15
5.2 Service Provisioning..............................................................................................................................................................15
5.3 UE and User............................................................................................................................................................................ 16
5.4 Service....................................................................................................................................................................................... 16
6 WTTx/MBB Hybrid Networking Solutions....................................................................... 17
6.1 WTTx and MBB UE Identification.................................................................................................................................... 17
6.2 WTTx and MBB UE Camping Policies.............................................................................................................................18
6.3 WTTx and MBB UE Handover Policies........................................................................................................................... 21
6.4 WTTx and MBB UE MLB Policies..................................................................................................................................... 22
6.5 QoS Policy for Co-Carrier Operations of WTTx and MBB Services...................................................................... 23
7 WTTx Capacity Expansion Solutions................................................................................. 25
7.1 DL 256QAM............................................................................................................................................................................ 25
7.2 MIMO........................................................................................................................................................................................ 25
7.3 Carrier Aggregation..............................................................................................................................................................26
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WTTx Overview Feature Parameter Description
Contents
7.4 WTTx Device-Pipe Synergy................................................................................................................................................ 26
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WTTx Overview Feature Parameter Description
1 Change History
1
Change History
This chapter describes changes not included in the "Parameters", "Counters",
"Glossary", and "Reference Documents" chapters. These changes include:
●
Technical changes
Changes in functions and their corresponding parameters
●
Editorial changes
Improvements or revisions to the documentation
1.1 eRAN18.1 01 (2022-03-08)
Technical Changes
None
Editorial Changes
Revised descriptions in this document.
1.2 eRAN18.1 Draft A (2021-12-30)
This issue introduces the following changes to eRAN17.1 02 (2021-11-27).
Technical Changes
Change Description
Parameter Change
RA
T
Base Station Model
None
None
FD
D
None
Editorial Changes
Revised descriptions in this document.
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WTTx Overview Feature Parameter Description
2
2 About This Document
About This Document
This document describes wireless to the x (WTTx) and its applications, WTTx/MBB
hybrid networking solutions, WTTx capacity improvement solutions, and
differences between WTTx and mobile broadband (MBB) networks.
This document applies to FDD.
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3 Introduction
3
Introduction
Many mobile operators started providing fixed wireless phone services in the 2G
era and, in the age of 3G, provided wireless broadband (WBB) access. WTTx uses
4G, that is Long Term Evolution (LTE), as its radio access technology. Thanks to its
abundant spectrum resources and high technological maturity, WTTx has become
the most popular option available for operators.
WTTx is different from fiber to the x (FTTx). WTTx is suitable for stationary
enterprise and household users and supports three types of services: virtual private
network (VPN), Voice over Internet Protocol (VoIP), and video. A WTTx UE is
indoor or outdoor customer-premises equipment (CPE). CPEs provide either Wi-Fi
coverage or access to wired local area networks for end users, as shown in Figure
3-1.
Figure 3-1 WTTx network architecture
With WTTx:
●
x digital subscriber line (xDSL) fixed network operators can deploy last-mile
wireless networks.
●
Worldwide Interoperability for Microwave Access (WiMAX) operators can
upgrade existing base stations to LTE TDD base stations.
For mobile operators who experience slow user development, fail to maintain
sustainable growth solely through mobile user development, and have abundant
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3 Introduction
spectrum resources in certain regions, WTTx fully leverages idle LTE air interface
resources to expand the scope of the WBB services that the mobile operators can
offer. This increases LTE spectral efficiency, revenue sources, and broadband
market share.
WTTx delivers fiber-like user experience and has the following advantages over
FTTx: rapider deployment, shorter payback period, and lower total cost of
operation (TCO). For these reasons, WTTx is suitable in sparsely populated areas
and in areas where FTTx networks are difficult to deploy.
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4 Application Scenarios
Application Scenarios
4.1 Households
WTTx provides high-quality household applications through cooperation between
Huawei, content providers, and operators as follows:
1.
Huawei deploys the WTTx network, which can be used to provide video and
VoIP services.
2.
Operators work with content providers to bundle video, music, and game
services with home broadband services.
3.
Operators use set-top boxes (STBs) and analyze user behavior with big data
to accurately and fully connect household applications. They also provide
automation, security, entertainment, monitoring, and care functions, creating
a smart home.
4.1.1 Video Service
Huawei's WTTx solution lets operators provide video services for households in
areas without optical fiber coverage. This solution overcomes obstacles to the
development of video services relying on FTTx networks. FTTx solutions often
require time-consuming outside plant (OSP) deployment and in some areas,
cannot be deployed at all.
Huawei uses the following technologies to guarantee video services on a WTTx
network:
●
LTE support for multicast services. For details about multicast services, see
eMBMS.
●
LTE adaptation to the video architecture
●
Flexible Internet Protocol over Ethernet (IPoE) authentication mechanism for
video wide area network (WAN) services
●
Differentiated services code point (DSCP)-based video QoS guarantee in WTTx
scenarios
The eNodeB preferentially schedules video packets based on DSCP values to
improve video playback experience. For details, see Video Experience
Optimization.
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4 Application Scenarios
4.1.2 VoIP Service
The WTTx solution supports voice services. Huawei provides three VoIP solutions:
●
VoIP over IP multimedia subsystem (IMS)
●
VoIP over non-geographic number (NGN)
●
VoIP over simple Internet Protocol (SIP) server
VoIP over IMS
VoIP over IMS is the only solution that supports both inter-RAT handovers and
handset roaming. VoIP over IMS is compatible with both MBB and WTTx.
Figure 4-1 Network architecture of VoIP over IMS
The functions of the SBC and PCRF are as follows:
●
●
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SBC
–
Controls media content and signaling of real-time session services on
different operating companies, including VoIP and video.
–
Guarantees the security of services running at cell edges (anti-attack,
VPN isolation, and firewalls), and performs QoS control (policing,
marking, rate limiting, call admission control, and service level
agreements).
–
Integrates the functions of the P-CSCF, ATCF, and ATGW, and supports
dynamic voice bearer setup and enhanced single radio voice call
continuity (eSRVCC).
PCRF
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4 Application Scenarios
–
Performs basic data service billing and policy management, such as the
fair usage policy (FUP), Turbo Button (TB), and Day Pass.
–
Supports the P-CSCF-triggered procedure for setting up voice bearers.
VoIP over IMS has the following characteristics:
●
Guarantees SRVCC/eSRVCC and inter-RAT voice continuity.
●
Adopts an E2E QoS solution.
●
–
For SIP bearers: The dual-access point name (APN) solution is
recommended for CPEs.
–
For voice bearers: A dynamic QoS mechanism based on policy and
charging control is adopted.
Prohibits the enabling of a SIP application-level gateway (ALG) for any
network address translation (NAT) NEs (such as a firewall) between the PGW and SBC. This is because the SBC uses the IP address in a SIP message to
set up a voice bearer.
VoIP over NGN
VoIP over NGN is suitable for fixed network operators, providing data services and
lowering costs by replacing landline telephones with VoIP.
Figure 4-2 Network architecture of VoIP over NGN
The network architecture of VoIP over NGN is similar to that of VoIP over IMS.
This network architecture has the following characteristics:
●
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The SBC does not provide P-CSCF functions or connect to the PCRF through
an Rx interface.
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●
4 Application Scenarios
This network architecture only supports handovers within E-UTRAN.
VoIP over SIP Server
VoIP over SIP server has a lower capital expenditure (CAPEX) than VoIP over IMS
or VoIP over NGN, which is more complex. VoIP over SIP server is suitable for
operators that have WiMAX networks or wish to deploy new WTTx networks.
Figure 4-3 Network architecture of VoIP over SIP server
VoIP over SIP server and VoIP over NGN use the same radio bearer layer, but VoIP
over SIP server delivers better service and better inter-network connectivity.
In regards to LTE QoS, VoIP bearers are set up differently for each of the three
VoIP solutions. These solutions use the same QoS guarantee mechanism for VoIP
bearers once they are set up. To select a VoIP solution, refer the following table.
Table 4-1 Selecting a VoIP solution
Scenario
Recommended Solution
MBB operators
VoIP over IMS
Operators with IMSs
WTTx operators planning an MBB evolution
Inventory NGN markets of WTTx operators
VoIP over NGN
Inventory SIP server markets of WTTx
operators
VoIP over SIP server
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Scenario
4 Application Scenarios
Recommended Solution
New WTTx networks of WTTx operators
without an IMS plan
4.2 Enterprises
Wireless to the enterprise (WTTe) is applicable to scenarios such as small office
and home office (SOHO), vending machines, electronic advertisements, small
offices, small hotels, and small and medium enterprise branches. Considering the
complexity of enterprise application networking, the ODU+AR architecture is
recommended to provide voice, data, and virtual private network (VPN) private
line services for users in these scenarios.
Figure 4-4 WTTe network architecture and main services
NOTE
In the preceding figure, the voice service in the WTTe scenario refers to the one with phone
numbers allocated by the operator.
4.2.1 Voice Service Solution
VLAN-based Services Differentiation
Voice services account for a larger proportion than data services (including DSL &
Fiber data services) in small- and medium-sized enterprises. To solve the problem
of poor voice quality and service quality for such customers, the virtual local area
network (VLAN)-based service differentiation solution is introduced to promote
the QoS solution deployment for voice services. Figure 4-5 shows the architecture
of VLAN-based service differentiation.
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Figure 4-5 VLAN-based service differentiation
In this solution:
●
VoIP uses the dual-APN architecture. The default APN transmits data services,
and the IMS APN transmits voice services.
●
The enterprise AR allocates different VLANs to voice and data services and
maps the VLANs to APNs.
NAT+SIP
Figure 4-6 NAT+SIP architecture
In this solution, the ODU provides the NAT and SIP ALG functions.
●
NAT: Translates network addresses and enables private networks to access
public networks.
●
SIP ALG: Implements NAT traversal.
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A common NAT device relies on the data transmission channel that is established
during the first data transmission from the private network to the public network.
After the channel is established, packets between two endpoints are then
forwarded through this channel. When a private network device (for example, a
VoIP terminal) attempts to negotiate with a public network device (for example,
an SIP Server) over the application layer to establish a new data transmission
channel for service provisioning, NAT traversal needs to be implemented by the
SIP ALG.
4.2.2 VPN Private Line Service Solution
The WTTx enterprise VPN private line solution enables an enterprise or an
organization to build VPNs, with which virtual links (tunnels) are established on
the public packet switched network to connect distributed branches to the
headquarters. Services of two enterprises are isolated from each other, and
employees of an enterprise can manage the enterprise intranet independently.
This solution saves the costs of leasing private lines and features security,
reliability, and manageability.
There are three types of networking in the WTTx enterprise VPN solution:
●
Integrated layer 3 VPN
An integrated layer 3 VPN is inexpensive and can be deployed quickly. A VPN
deployed using this scheme only involves three network elements: CPEs, an
authentication authorization answer (AAA), and a PDN gateway (P-GW). VPN
billing and management are performed by the LTE network.
●
Layer 2 Tunneling Protocol (L2TP) layer 3 VPN
In this universal layer 3 VPN scheme, VPN functions are implemented using
an access router (AR) and an L2TP network server (LNS). This scheme uses
eNodeBs and evolved packet core (EPC) NEs as transmission channels. This
scheme has no other requirements on the LTE network.
●
L2TP layer 2 VPN
This scheme requires two ARs, one deployed as an L2TP access concentrator
(LAC) at a branch of an enterprise and the other as an LNS at the enterprise
headquarters. This scheme uses eNodeBs and EPC NEs as transmission
channels. It places no other requirements on the LTE network. With this
scheme, WiMAX networks can be smoothly converted into LTE TDD networks.
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4.2.3 ODU Management and Enhancement
ODU+AR Remote Management Solution
Figure 4-7 ODU+AR remote management architecture
In this solution, the AR and the ODU are managed separately, with the former
managed using a third-party NMS and the latter remotely managed through the
LTM.
As shown in Figure 4-7, the ODU carries two APNs, one for data transmission, and
the other for ODU management. The two APNs are assigned different IP
addresses. The AR directly uses the transparently transmitted IP address for
management. The IP address transparent transmission solution is used between
the ODU and the LAN. The IP address allocated by the network is allocated to the
LAN through DHCP.
ODU Reliability Improvement Solution
Figure 4-8 Dual-ODU backup architecture
In scenarios requiring high reliability, the wireless + wireless (or wireless + wired)
dual-backup architecture can be used to provide protection, as shown in Figure
4-8. When the main service is normal, the active link is used for transmission.
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When the AR detects a fault on the active link, services are switched over to the
standby link to ensure normal operation.
4.3 WTTx Community Scenario
Huawei provides the ODU-to-building solution for emerging markets that are
more cost sensitive. In this solution, an outdoor high-performance CPE is installed
on a street pole and connected to a router over an Ethernet cable to provide
network access to household users. In this solution, a high-performance CPE is
used as the access point of multiple home broadband networks to accommodate
their traffic requirements.
This solution has the following advantages:
●
Allows for outdoor CPE installation at an optimal location after site survey.
Achieves optimal pairing performance and maximizes spectral efficiency in
massive MIMO scenarios, increasing the number of supported WTTx UEs.
●
Lowers requirements for UE performance and requires only the use of routers
in common households.
●
Allows sharing costs of a high-end CPE among multiple households to
improve the profitability.
4.3.1 Operator-ISP Coordination Solution
Figure 4-9 Networking for the operator-ISP coordination solution
Figure 4-9 shows the networking for the operator-ISP coordination solution. In the
networking:
●
The NEs in the red box are operated by the Internet service provider (ISP).
The ISP needs to install the third-party router (LAN switch), connect cables in
the target building, manage the home gateway (HG), and provide network
access services and authentication, authorization, and charging for users.
The LAN switch provides the authentication, authorization, service isolation,
bandwidth limiting, and other functions for each UE. It cannot perform
accounting as the broadband remote access server (BRAS) does or provide the
value-added service (VAS). The LAN switch hosts the following functions:
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–
PPPoE access, in which only authenticated users with authorized accounts
can access the Internet.
–
Isolation of HG services
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●
–
Bandwidth limiting
–
Firewall
4 Application Scenarios
The NEs in the green box are provided by the operator.
The EPC and eNodeB can provide radio channels just as they do on legacy
networks. The ISP leases bandwidth from the operator without the need of
changing the configuration.
4.3.2 Fixed Mobile Convergence Solution
Figure 4-10 Networking for the fixed mobile convergence solution
To address such issues as high last-mile costs in many broadband deployment
solutions (such as using optical fibers) and prohibitive high-end outdoor CPEs,
Huawei proposes a CPE deployment mode similar to the cabinet-to-building
deployment mode (in which optical fiber cabinets are deployed on streets). Figure
4-10 shows the networking of this solution. Home routers are used as HGs, and
the LSW, CPE, eNodeB, and EPC together provide a pipe for establishing an L2TP
tunnel between the BRAS and each home router to transmit data packets.
The functions and requirements of the NEs in this solution are as follows:
●
The operation system BOSS and billing system BRAS of the fixed network still
maintains the original registration, authentication, charging, and bandwidth
control functions.
●
The CRM implements service provisioning and charging.
●
The AAA authenticates and authorizes users.
●
HGs need to support L2TP tunnel setup and dialup to the BRAS. HGs do not
manage the CPE.
The disadvantages of this solution are high requirements for household routers
and high costs.
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5
5 Differences Between WTTx and MBB Networks
Differences Between WTTx and MBB
Networks
5.1 Site
WTTx site planning differs from MBB site planning in the following ways:
●
WTTx sites are deployed in key areas, such as residential areas, that require
extra coverage. These sites can be used to provide targeted instead of
contiguous coverage to supplement existing sites.
●
There is no need of new site deployment in remote sparsely populated
suburbs. Carrier expansion suffices, or even such expansion is also not
required.
●
WTTx site locations must be selected based on the WTTx service provisioning
strategy for the main service area of an operator.
–
Fixed network operators who need to add LTE TDD networks to provide
broadband access services can collaborate with mobile operators for
deployment.
–
Operators that plan to provide WTTx services on existing LTE TDD
networks with low physical resource block (PRB) usages need to evaluate
whether new sites are required in key areas.
–
LTE FDD mobile operators that have already provided WTTx services and
need to deploy TDD networks can purchase LTE TDD spectrum and
offload traffic of LTE FDD sites with high PRB usages to new LTE TDD
sites.
5.2 Service Provisioning
Unlike MBB networks, WTTx networks serve stationary UEs. The WTTx service
provisioning strategy is as follows:
●
Operators use the WTTx map to determine whether to provide WTTx services
to users based on their home address.
–
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If a user lives in an area covered by WTTx networks, WTTx services can be
provided to this user.
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–
5 Differences Between WTTx and MBB Networks
If a user lives in an area covered by a heavy-load WTTx network, only a
low-speed WTTx service package can be provided.
●
Unconditional service provisioning is recommended only in remote areas.
●
Operators need to design WTTx service packages based on their development,
network load, and market competition.
●
WTTx service packages can be monthly plans where speed may be limited,
but not data, just like fixed network service packages. However, the activation
rate for WTTx service packages with unlimited data usage is high, especially in
the initial stages. This calls for more WTTx network capacity.
5.3 UE and User
WTTx UEs:
●
Are indoor or outdoor CPEs with high-gain directional antennas (indoor CPEs:
6 dBi to 8 dBi; outdoor CPEs: 12 dBi to 16 dBi).
●
Are stationary and do not require power conservation.
WTTx and MBB users are different in the following two ways:
●
The average activation rate of WTTx users is 12% to 15%, while that for MBB
users is 2% to 5%.
●
The online time of WTTx users is 180s to 300s, while that of MBB users is 24s
to 40s.
5.4 Service
The differences between WTTx and MBB services are as follows:
●
Large-packet services (over 1440 bytes) make up approximately 40% and
22% of the services on WTTx and MBB networks respectively.
●
The downlink throughput of a single WTTx UE is 190 kbit/s to 260 kbit/s,
while that of an MBB UE is 30 kbit/s to 140 kbit/s.
●
The average downlink PRB usage of a WTTx network exceeds 40%. On an
MBB network it is less than 10%. The average uplink PRB usage of a WTTx
network reaches approximately 50%, while that of an MBB network only
reaches about 20%.
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6
6 WTTx/MBB Hybrid Networking Solutions
WTTx/MBB Hybrid Networking Solutions
Huawei provides rate limitation and resource allocation solutions for WTTx/MBB
hybrid networks where operators wish to assign different QoS priorities to WTTx
and MBB services, and prioritize MBB user experience. These solutions prevent the
network overload and MBB KPI deterioration caused by the additional WTTx
services.
6.1 WTTx and MBB UE Identification
Identification of WTTx and MBB UEs is a key issue for WTTx/MBB hybrid networks.
Huawei provides identification methods based on:
●
Service profile identifier (SPID)
●
QoS class identifier (QCI)
●
International mobile equipment identity type allocation code (IMEI-TAC)
●
International mobile subscriber identity (IMSI)
NOTE
● In WBB, WBB UEs refer to UEs identified based on their SPIDs or QCIs. In Specified User
Coordinated Scheduling, WTTx UEs refer to those identified using device-pipe
identification.
● In this document, "WTTx UEs" includes both "WBB UEs" and "WTTx UEs" mentioned in
these two feature parameter descriptions.
● WTTx device-pipe synergy is a trial feature, and the device-pipe identification function of
this feature is not described in this document. For details about this function, see
Specified User Coordinated Scheduling.
SPID-based Identification
An SPID is equivalent to an RAT/Frequency Selection Priority (RFSP) on the EPC
side. An SPID is a policy index that the operator specifies for a UE in the database
of the home subscriber server (HSS). SPIDs range from 1 to 256. The eNodeB
performs special service operations and provides targeted services for UEs based
on their SPIDs.
SPIDs 1 and 2 are planned for WTTx and MBB UEs. Preferential camping policies
are configured for these UEs on the eNodeB side.
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6 WTTx/MBB Hybrid Networking Solutions
●
UEs with SPID 1 preferentially camp on LTE TDD carriers.
●
UEs with SPID 2 preferentially camp on LTE FDD carriers.
Service policies of WTTx UEs are conveyed to other NEs through SPID
transmission. Figure 6-1 shows how an SPID is broadcast to the entire network.
For details, see WBB.
Figure 6-1 Process of broadcasting an SPID on the entire network
QCI-based Identification
QoS classes are defined for LTE bearers. Operators can specify different QCIs for
default bearers of WTTx and MBB UEs on the HSS. Lower-layer NEs use QCIs to
identify UEs. For details, see WBB.
Other Methods
WTTx and MBB UEs can be identified based on the IMEI-TAC, IMSI, or other
factors. The eNodeB is not involved in these identification processes.
6.2 WTTx and MBB UE Camping Policies
Huawei provides WTTx and MBB UE camping solutions for fixed and mobile
network operators that collaborate to provide WBB and MBB services using
different carriers.
SPID-based Preferential Camping Policy
A cell reselection policy specifies whether UEs preferentially camp on a cell
working on a certain frequency used for GERAN, UTRAN, CDMA2000 1xRTT,
CDMA2000 HRPD, or E-UTRAN. Operators can use SPIDs to correlate cell
reselection policies with UEs. The eNodeB contains an SPID-specific priority in the
IdleModeMobilityControlInfo IE in an RRC Connection Release message sent to a
UE. This SPID-specific priority is dedicated to cell reselection.
When delivering SPID-specific priorities, the eNodeB retrieves the stored SPIDspecific frequency list and corresponding frequency priorities to form a frequency
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6 WTTx/MBB Hybrid Networking Solutions
priority list. Then, the eNodeB filters the frequencies based on UE capabilities and
target PLMN and includes the remaining frequencies in the IE IMMCI sent to UEs.
Figure 6-2 SPID-specific cell reselection policy
Carrier Differentiation for WTTx and MBB Services
If a network has two or more carriers, you can add MBB-service-prioritized and
WBB-service-specified cells to provide WTTx and MBB services using different
carriers. With this policy: WTTx UEs cannot be handed over to MBB-serviceprioritized cells, and if they access such cells, they initiate handovers to leave such
cells; MBB UEs cannot be handed over to WBB-service-specified cells, and if they
access such cells, they initiate handovers to leave such cells. WTTx UEs cannot
camp on MBB carriers or perform services on these carriers, and MBB UEs cannot
camp on WBB carriers or perform services on such carriers. For details, see WBB.
Figure 6-3 Separate operation of WTTx and MBB services on different carriers
Cell Locking Based on the Zone Code-IMSI Table or IMEIs (Performed by the
MME)
The MME can specify what areas (identified by the LAC, RAC, SAC, or TAC) a
certain type of UEs can or cannot access. This policy is suitable in scenarios where
many UEs of different types are required to access only specific areas and these
areas overlap. For example, WTTx UEs can only access LTE TDD networks, and
MBB UEs can only access LTE FDD networks.
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Figure 6-4 Cell locking configuration for WTTx and MBB UEs
Cell Locking Based on the Cell-IMSI Table (Performed by the PCRF)
The PCRF applies a cell locking policy by configuring an accessible cell list for
every UE.
Operators configure the cell locking policy corresponding to the IMSI of a UE
using the business and operation support system (BOSS) and synchronize the
policy to the PCRF. When a UE accesses a network, the SAE-GW obtains the cell
locking policy corresponding to the IMSI of the UE from the PCRF, and reports the
E-UTRAN cell global identifier (ECGI) of the serving cell. If the ECGI is not in the
accessible cell list, the UE is detached.
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Figure 6-5 Cell locking for WTTx UEs
6.3 WTTx and MBB UE Handover Policies
Handover policies used for WTTx UEs are different from those used for MBB UEs.
For details, see Mobility Management in Connected Mode.
Suppression of WTTx UE Handovers
WTTx UEs are often stationary, and operators expect no WTTx UE mobility.
Therefore, intra- and inter-frequency handover threshold offset factors are set for
WTTx UEs to suppress their handovers. In this way, WTTx service stability can be
improved.
Preferential Coverage-based Handovers to LTE FDD or LTE TDD Frequencies
The eNodeB allows different event A2 parameters to be set for target LTE FDD
and LTE TDD frequencies so that coverage-based handovers to LTE FDD or LTE
TDD frequencies can be preferentially triggered.
Event A2 indicates that the signal quality of the serving cell is lower than a
threshold. If a UE reports event A2, the eNodeB delivers inter-frequency
measurement configurations to the UE. You can set different priorities of LTE FDD
and LTE TDD frequencies for coverage-based blind redirections or handovers.
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6.4 WTTx and MBB UE MLB Policies
MLB
During mobility load balancing (MLB) on WTTx and MBB hybrid networks,
operators expect to restrict the transfer of WTTx UEs because they can use the
WTTx map to balance WTTx load.
SPID-based inter-frequency MLB is controlled by the SpidCfg.InterFreqMlbSwitch
parameter, and SPID-based MLB for UEs in idle mode is controlled by the
SpidCfg.IdleMlbSwitch parameter. For details, see Intra-RAT Mobility Load
Balancing.
Figure 6-6 WTTx and MBB UE MLB policies
Quick Outgoing Handovers for WBB UEs with Low Uplink Traffic (FDD)
If WBB UEs camp on FDD cells for long periods and occupy PRB resources, MBB
user experience may be significantly affected. To prevent such issues, Huawei
introduces the function of quick outgoing handovers for WBB UEs with low uplink
traffic. After this function takes effect, the eNodeB only transfers WBB UEs with
low uplink traffic (including UEs without uplink services) out of FDD cells, as
shown in Figure 6-7. For details, see WBB.
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Figure 6-7 Quick outgoing handovers for WBB UEs with low uplink traffic
6.5 QoS Policy for Co-Carrier Operations of WTTx and
MBB Services
Huawei provides QoS solutions regarding rate limitation and resource allocation
on WTTx and MBB hybrid networks for operators with different network
conditions. These solutions resolve the following operators' QoS requirements for
WTTx and MBB hybrid networks: WTTx UEs can use as many network resources as
possible during off-peak hours; During peak hours, the scheduling for WTTx UEs
must not affect that for MBB UEs, while the experience of WTTx UEs is
guaranteed.
UE-AMBR-based Differentiation
This solution limits the total rate of all non-guaranteed bit rate (GBR) bearers of a
UE. The UE rate cannot exceed the aggregate maximum bit rate (AMBR)
regardless of whether congestion occurs. Operators can specify different UEAMBRs for WTTx and MBB UEs on the HSS or PCRF to provide differentiated
services for these UEs.
Figure 6-8 UE-AMBR-based differentiation
DACQ-based Differentiation
This solution uses QCIs to identify WTTx and MBB UEs and dynamically limits the
AMBR of WTTx UEs in heavy-load cells. This reduces the impact of WTTx UEs on
MBB networks and maintains MBB user experience. For details about dynamic
AMBR control by QCI (DACQ), see Rate Control Based on User Types.
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Differentiated SPID- or QCI-based Scheduling Priorities
The eNodeB provides different scheduling services for UEs over the air interface
based on the QCIs delivered by the EPC. QCI-based scheduling priorities can be
used to distinguish WTTx and MBB UEs running different type of services. The
eNodeB places data packets in different priority queues based on QCIs and
preferentially schedules data packets in queues of higher priorities.
If QCIs are unavailable or insufficient, SPID-based scheduling priorities can be
used to distinguish UEs. The bearer scheduling priority of a UE equals the QCIspecific scheduling priority multiplied by the SPID-specific scheduling priority
coefficient.
If this solution is implemented, WTTx and MBB rates are the same in light-load
scenarios, but the experience of low-priority UEs significantly deteriorates at heavy
loads. Exercise caution when setting parameters to avoid huge experience
differences of low-price packaged WTTx services between peak and off-peak
hours. For details, see WBB.
Figure 6-9 Differentiated SPID- or QCI-based scheduling priorities
Control over the Maximum PRB Usages for WTTx and MBB UEs
The PRB usage of WTTx and MBB UEs is controlled by setting the upper limits to
avoid significant impact on MBB user experience due to PRB overuse of WTTx UEs
and avoid PRB unavailability for WTTx UEs due to PRB overuse of MBB UEs.
The eNodeB can identify WTTx and MBB UEs based on SPIDs or QCIs, set high
priorities for MBB UEs, and set different maximum PRB usages for WTTx and MBB
UEs. PRB resources are allocated to these UEs based on the preset usage limits.
For details, see WBB.
Uplink and Downlink Rate Guarantee for WTTx/MBB UEs
Differentiated guaranteed rates are provided for UEs as follows: The eNodeB
identifies different UEs based on their QCIs or SPIDs. The eNodeB guarantees the
downlink GBR and uplink minimum GBR in best-effort mode on default non-GBR
bearers of specific UEs. This provides UE-differentiated experience. For details, see
Rate Control Based on User Types and Scheduling.
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7 WTTx Capacity Expansion Solutions
WTTx Capacity Expansion Solutions
Unlike MBB UEs, most WTTx UEs (CPEs) are stationary and use high-gain
directional antennas. WTTx users tend to place CPEs at locations with good signal
quality, such as by windows. For these reasons, CPEs obtain considerable gains
from eRAN features aimed to improve spectral efficiency.
7.1 DL 256QAM
DL 256 Quadrature Amplitude Modulation (256QAM) improves uplink and
downlink transmission efficiency for UEs with good signal quality and fulfills
service rate requirements. For details, see Modulation Schemes.
Figure 7-1 Gains offered by DL 256QAM
7.2 MIMO
If transmit and receive antenna channels are mutually orthogonal and signals
from the transmit antennas are mutually independent and transmitted at the
same rate in an MxN multiple-input multiple-output (MIMO) system, this system
brings a theoretical spatial multiplexing order of Min(M, N) compared with a
single-antenna transmission system. Min(M, N) indicates the smaller number of M
and N, which represent the number of transmit antennas and number of receive
antennas. The multiplexing order theoretically represents the spatial channel
capacity. For details, see MIMO.
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Figure 7-2 MIMO multiplexing gains
7.3 Carrier Aggregation
Carrier aggregation (CA) allows a CA-capable UE to use idle resources on noncontiguous spectrums to provide more bandwidth. In this way, a single UE can
reach higher uplink and downlink peak data rates. Figure 7-3 illustrates the gains
offered by CA. This figure is for reference only. For details about the gains and
principles, see Carrier Aggregation.
Figure 7-3 Gains offered by CA
7.4 WTTx Device-Pipe Synergy
Wireless to the x (WTTx) device-pipe synergy refers to the synergy between the
eNodeB and UEs capable of device-pipe synergy. Currently these UEs are mainly
customer-premises equipment (CPE) deployed for WTTx. WTTx device-pipe synergy
provides a range of functions on the UE and eNodeB sides and on the pipe
between the eNodeB and UEs to improve WTTx performance or enhance services.
For details, see Specified User Coordinated Scheduling.
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