U.S. patent number 9,271,203 [Application Number 12/883,986] was granted by the patent office on 2016-02-23 for alternate transmission scheme for high speed packet access (hspa).
This patent grant is currently assigned to QUALCOMM Incorporated. The grantee listed for this patent is Tom Chin, Kuo-Chun Lee, Guangming Shi. Invention is credited to Tom Chin, Kuo-Chun Lee, Guangming Shi.
United States Patent |
9,271,203 |
Chin , et al. |
February 23, 2016 |
Alternate transmission scheme for high speed packet access
(HSPA)
Abstract
Post-hard handover processing in a Time Division--Synchronous
Code Division Multiple Access (TD-SCDMA) network may be improved to
allow operation of High Speed Packet Access (HSPA) in hard
handover. For example, uplink synchronization may be completed
concurrent with HSPA to quickly resume HSPA operation in hard
handovers. User Equipment (UE) may receive downlink data while
completing uplink synchronization. In another example, a unique
SYNC_UL code may be assigned to a UE for hard handover. The unique
SYNC_UL code allows Node Bs of the TD-SCDMA network to know which
UE is performing hard handover. When a Node B is receiving the
unique SYNC_UL, the Node B may begin to allocate UL data grants.
After receiving UL data from the UE, the Node B may resume High
Speed Downlink Packet Access (HSDPA).
Inventors: |
Chin; Tom (San Diego, CA),
Shi; Guangming (San Diego, CA), Lee; Kuo-Chun (San
Diego, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Chin; Tom
Shi; Guangming
Lee; Kuo-Chun |
San Diego
San Diego
San Diego |
CA
CA
CA |
US
US
US |
|
|
Assignee: |
QUALCOMM Incorporated (San
Diego, CA)
|
Family
ID: |
44343138 |
Appl.
No.: |
12/883,986 |
Filed: |
September 16, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20110292909 A1 |
Dec 1, 2011 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61348140 |
May 25, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
36/0077 (20130101); H04W 56/00 (20130101); H04W
72/14 (20130101); H04W 36/08 (20130101) |
Current International
Class: |
H04W
4/00 (20090101); H04W 36/00 (20090101); H04W
56/00 (20090101); H04W 72/14 (20090101); H04W
36/08 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1848706 |
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Oct 2006 |
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CN |
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2006072811 |
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Jul 2006 |
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WO |
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WO2006110774 |
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Oct 2006 |
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WO |
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Other References
International Search Report and Written Opinion--PCT/US2011/037995,
International Search Authority--European Patent Office--Aug. 25,
2011. cited by applicant .
Li Shine et al: "TD-SCDMA RTT", Dec. 1, 2004, pp.
39-43,XP55004487,Retrieved from the Internet:URL:http://www.chi
na-cic.org.cn/english/digital library/2004121.pdf. cited by
applicant.
|
Primary Examiner: Young; Steve
Attorney, Agent or Firm: Ekwueme; Kristine U.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. provisional patent
application No. 61/348,140 filed May 25, 2010, in the names of CHIN
et al., the disclosure of which is expressly incorporated by
reference in its entirety.
Claims
What is claimed is:
1. A method for performing a handover in a Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA)
network, comprising: receiving an uplink synchronization code
unique to a user equipment (UE) from a source Node B (NB) of the
TD-SCDMA network; performing uplink synchronization with a target
Node B (NB) of the TD-SCDMA network after changing both downlink
and uplink channels from the source NB to the target NB to stop
high speed data communication including high speed downlink data
from the source NB and high speed uplink data to the source NB at
an activation time specified by the TD-SCDMA network and
communicated to the UE, the activation time indicating a time
during which handover of the high speed data communication with the
target NB occurs; receiving a data uplink grant assigning network
resources for resuming sending uplink data and receiving high speed
downlink data from the target NB before completion of the uplink
synchronization, the data uplink grant allocated to the UE based at
least in part on the uplink synchronization code unique to the UE,
the uplink data sent to the target NB and the high speed downlink
data from the target NB associated with the high speed data
communication handed over from the source NB.
2. The method of claim 1, further comprising transmitting a message
to the target NB after completion of the uplink synchronization,
wherein the message indicates completion of the handover.
3. A computer program product for performing a handover in a Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA)
network, comprising: a non-transitory computer-readable medium
comprising: code to receive an uplink synchronization code unique
to a user equipment (UE) from a source Node B (NB) of the TD-SCDMA
network; code to perform uplink synchronization with a target Node
B (NB) of the TD-SCDMA network after changing both downlink and
uplink channels from the source NB to the target NB to stop high
speed data communication including high speed downlink data from
the source NB and high speed uplink data to the source NB at an
activation time specified by the TD-SCDMA network and communicated
to the UE, the activation time indicating a time during which
handover of the high speed data communication with the target NB
occurs; and code to receive a data uplink grant assigning network
resources for resuming sending uplink data and to receive high
speed downlink data from the target NB before completion of the
uplink synchronization, the data uplink grant allocated to the UE
based at least in part on the uplink synchronization code unique to
the UE, the uplink data sent to the target NB and the high speed
downlink data from the target NB associated with the high speed
data communication handed over from the source NB.
4. The computer program product of claim 3, wherein the medium
further comprises code to transmit a message to the target NB after
completion of the uplink synchronization indicating completion of
the handover.
5. An apparatus for performing a handover in a Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA)
network, comprising: at least one processor; and a memory coupled
to the at least one processor, wherein the at least one processor
is configured: to receive an uplink synchronization code unique to
a user equipment (UE) from a source Node B (NB) of the TD-SCDMA
network; to perform uplink synchronization with a target Node B
(NB) of the TD-SCDMA network after changing both downlink and
uplink channels from the source NB to the target NB to stop high
speed data communication including high speed downlink data from
the source NB and high speed uplink data to the source NB at an
activation time specified by the TD-SCDMA network and communicated
to the UE, the activation time indicating a time during which
handover of the high speed data communication with the target NB
occurs; and to receive a data uplink grant assigning network
resources for resuming sending uplink data and to receive high
speed downlink data from the target NB before completion of the
uplink synchronization, the data uplink grant allocated to the UE
based at least in part on the uplink synchronization code unique to
the UE, the uplink data sent to the target NB and the high speed
downlink data from the target NB associated with the high speed
data communication handed over from the source NB.
6. The apparatus of claim 5, wherein the at least one processor is
further configured to transmit a message to the target NB after
completion of the uplink synchronization indicating completion of
the handover.
7. An apparatus for performing a handover in a Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA)
network, comprising: means for receiving an uplink synchronization
code unique to a user equipment (UE) from a source Node B (NB) of
the TD-SCDMA network; means for performing uplink synchronization
with a target Node B (NB) of the TD-SCDMA network after changing
both downlink and uplink channels from the source NB to the target
NB to stop high speed data communication including high speed
downlink data from the source NB and high speed uplink data to the
source NB at an activation time specified by the TD-SCDMA network
and communicated to the UE, the activation time indicating a time
during which handover of the high speed data communication with the
target NB occurs; and means for receiving a data uplink grant
assigning network resources for resuming sending uplink data and
for receiving high speed downlink data from the target NB before
completion of the uplink synchronization, the data uplink grant
allocated to the UE based at least in part on the uplink
synchronization code unique to the UE, the uplink data sent to the
target NB and the high speed downlink data from the target NB
associated with the high speed data communication handed over from
the source NB.
8. The apparatus of claim 7, further comprising means for
transmitting a message to the target NB after completion of the
uplink synchronization, wherein the message indicates completion of
the handover.
9. A method for performing a handover in a Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA)
network, comprising: receiving an uplink synchronization code
unique to a User Equipment (UE) from a source Node B (NB) of the
TD-SCDMA network; changing both downlink and uplink channels from
the source NB to a target NB to stop high speed data communication
including high speed downlink data from the source NB and high
speed uplink data to the source NB at an activation time specified
by the TD-SCDMA network and communicated to the UE, the activation
time indicating a time during which handover of the high speed data
communication with the target NB occurs; transmitting the uplink
synchronization code to the target NB of the TD-SCDMA network after
the activation time in accordance with an uplink synchronization;
receiving a data uplink grant assigning network resources for
resuming sending uplink data and receiving high speed downlink data
from the target NB before completion of the uplink synchronization,
the data uplink grant allocated to the UE based at least in part on
the uplink synchronization code unique to the UE; and resuming high
speed data communication including sending uplink data and
receiving high speed downlink data from the target NB before
completion of the uplink synchronization, the high speed data
communication with the target NB associated with the high speed
data communication handed over from the source NB.
10. The method of claim 9, further comprising: receiving a
synchronization acknowledgement; and transmitting a message to the
target NB, the message indicating completion of the handover.
11. The method of claim 9, wherein the uplink synchronization code
comprises one of a set of synchronization codes for the
handover.
12. A computer program product for performing a handover in a Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA)
network, comprising: a non-transitory computer-readable medium
comprising: code to receive an uplink synchronization code unique
to a User Equipment (UE) from a source Node B (NB) of the TD-SCDMA
network; code to change both downlink and uplink channels from the
source NB to a target NB to stop high speed data communication
including high speed downlink data from the source NB and high
speed uplink data to the source NB at an activation time specified
by the TD-SCDMA network and communicated to the UE, the activation
time indicating a time during which handover of the high speed data
communication to the target NB occurs; code to transmit the uplink
synchronization code to the target NB of the TD-SCDMA network after
the activation time in accordance with an uplink synchronization;
code to receive a data uplink grant assigning network resources for
resuming sending uplink data and receiving high speed downlink data
from the target NB before completion of the uplink synchronization,
the data uplink grant allocated to the UE based at least in part on
the uplink synchronization code unique to the UE; and code to
resume high speed data communication including sending uplink data
and receiving high speed downlink data from the target NB before
completion of the uplink synchronization, the high speed data
communication with the target NB associated with the high speed
data communication handed over from the source NB.
13. The computer program product of claim 12, wherein the medium
further comprises: code to receive a synchronization
acknowledgement; and code to transmit a message to the target NB,
the message indicating completion of the handover.
14. The computer program product of claim 12, wherein the uplink
synchronization code comprises one of a set of synchronization
codes for the handover.
15. An apparatus for performing a handover in a Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA)
network, the apparatus comprising: at least one processor; and a
memory coupled to the at least one processor, wherein the at least
one processor is configured: to receive an uplink synchronization
code unique to a User Equipment (UE) from a source Node B (NB) of
the TD-SCDMA network; to change both downlink and uplink channels
from the source NB to a target NB to stop high speed data
communication including high speed downlink data from the source NB
and high speed uplink data to the source NB at an activation time
specified by the TD-SCDMA network and communicated to the UE, the
activation time indicating a time during which handover of the high
speed data communication to the target NB occurs; to transmit the
uplink synchronization code to the target NB of the TD-SCDMA
network after the activation time in accordance with an uplink
synchronization; to receive a data uplink grant assigning network
resources for resuming sending uplink data and receiving high speed
downlink data from the target NB before completion of the uplink
synchronization, the data uplink grant allocated to the UE based at
least in part on the uplink synchronization code unique to the UE;
and to resume high speed data communication including sending
uplink data and receiving high speed downlink data from the target
NB before completion of the uplink synchronization, the high speed
data communication with the target NB associated with the high
speed data communication handed over from the source NB.
16. The apparatus of claim 15, wherein the at least one processor
is further configured: to receive a synchronization
acknowledgement; and to transmit a message to the target NB, the
message indicating completion of the handover.
17. The apparatus of claim 15, wherein the uplink synchronization
code is unique to the UE for the handover.
18. An apparatus for performing a handover in a Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA)
network, comprising: means for receiving an uplink synchronization
code unique to a User Equipment (UE) from a source Node B (NB) of
the TD-SCDMA network; means for changing both downlink and uplink
channels from the source NB to a target NB to stop high speed data
communication including high speed downlink data from the source NB
and high speed uplink data to the source NB at an activation time
specified by the TD-SCDMA network and communicated to the UE, the
activation time indicating a time during which handover of the high
speed data communication to the target NB occurs; means for
transmitting the uplink synchronization code to the target NB of
the TD-SCDMA network after the activation time in accordance with
an uplink synchronization; means for receiving a data uplink grant
assigning network resources for resuming sending uplink data and
receiving high speed downlink data from the target NB before
completion of the uplink synchronization, the data uplink grant
allocated to the UE based at least in part on the uplink
synchronization code unique to the UE; and means for resuming high
speed data communication including sending uplink data and
receiving high speed downlink data from the target NB before
completion of the uplink synchronization, the high speed data
communication with the target NB associated with the high speed
data communication handed over from the source NB.
19. The apparatus of claim 18, further comprising: means for
receiving a synchronization acknowledgement; and means for
transmitting a message to the target NB, the message indicating
completion of the handover.
20. The apparatus of claim 18, wherein the uplink synchronization
code is unique to the UE for the handover.
Description
BACKGROUND
1. Field
Aspects of the present disclosure relate, in general, to wireless
communication systems, and more particularly, to facilitating high
performance during High Speed Packet Access (HSPA) in a Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA)
network.
2. Background
Wireless communication networks are widely deployed to provide
various communication services such as telephony, video, data,
messaging, broadcasts, and so on. Such networks, which are usually
multiple access networks, support communications for multiple users
by sharing the available network resources. One example of such a
network is the Universal Terrestrial Radio Access Network (UTRAN).
The UTRAN is the radio access network (RAN) defined as a part of
the Universal Mobile Telecommunications System (UMTS), a third
generation (3G) mobile phone technology supported by the 3rd
Generation Partnership Project (3GPP). The UMTS, which is the
successor to Global System for Mobile Communications (GSM)
technologies, currently supports various air interface standards,
such as Wideband--Code Division Multiple Access (W-CDMA), Time
Division--Code Division Multiple Access (TD-CDMA), and Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA). For
example, China is pursuing TD-SCDMA as the underlying air interface
in the UTRAN architecture with its existing GSM infrastructure as
the core network. The UMTS also supports enhanced 3G data
communications protocols, such as High Speed Downlink Packet Data
(HSDPA), which provides higher data transfer speeds and capacity to
associated UMTS networks.
As the demand for mobile broadband access continues to increase,
research and development continue to advance the UMTS technologies
not only to meet the growing demand for mobile broadband access,
but to advance and enhance the user experience with mobile
communications.
SUMMARY
In one aspect of the disclosure, a method for performing a handover
in a Time Division--Synchronous Code Division Multiple Access
(TD-SCDMA) network includes performing uplink synchronization with
a target Node B (NB) of the TD-SCDMA network. The method also
includes receiving an uplink grant and high speed downlink data
from the target NB before completion of the uplink
synchronization.
In another aspect, a computer program product for communicating in
a wireless network includes a computer-readable medium having code
to perform uplink synchronization with a target Node B (NB) of the
TD-SCDMA network. The medium also includes code to receive an
uplink grant and high speed downlink data from the target NB before
completion of the uplink synchronization.
In yet another aspect, an apparatus for communicating in a wireless
network includes a processor and a memory coupled to the processor.
The processor is configured to perform uplink synchronization with
a target Node B (NB) of the TD-SCDMA network. The processor is also
configured to receive an uplink grant and high speed downlink data
from the target NB before completion of the uplink
synchronization.
In a further aspect, an apparatus for communicating in a wireless
network includes means for performing uplink synchronization with a
target Node B (NB) of the TD-SCDMA network. The apparatus also
includes means for receiving an uplink grant and high speed
downlink data from the target NB before completion of the uplink
synchronization.
In one aspect, a method for performing a handover in a Time
Division--Synchronous Code Division Multiple Access (TD-SCDMA)
network includes receiving an uplink synchronization code
associated with a User Equipment (UE) from a source Node B (NB) of
the TD-SCDMA network. The method also includes transmitting the
uplink synchronization code to a target NB of the TD-SCDMA
network.
In another aspect, a computer program product for communicating in
a wireless network includes a computer-readable medium having code
to receive an uplink synchronization code associated with a User
Equipment (UE) from a source Node B (NB) of the TD-SCDMA network.
The medium also includes code to transmit the uplink
synchronization code to a target NB of the TD-SCDMA network.
In yet another aspect, an apparatus for communicating in a wireless
network includes a processor and a memory coupled to the processor.
The processor is configured to receive an uplink synchronization
code associated with a User Equipment (UE) from a source Node B
(NB) of the TD-SCDMA network. The processor is also configured to
transmit the uplink synchronization code to a target NB of the
TD-SCDMA network.
In a further aspect, an apparatus for communicating in a wireless
network includes means for receiving an uplink synchronization code
associated with a User Equipment (UE) from a source Node B (NB) of
the TD-SCDMA network. The apparatus also includes means for
transmitting the uplink synchronization code to a target NB of the
TD-SCDMA network.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating an example of a
telecommunications system.
FIG. 2 is a block diagram conceptually illustrating an example of a
frame structure in a telecommunications system.
FIG. 3 is a block diagram of a Node B in communication with a user
equipment in a radio access network.
FIG. 4 is a block diagram illustrating carrier frequencies in a
multi-carrier TD-SCDMA communication system.
FIG. 5 is a call flow showing a hard handover in a TD-SCDMA network
according to one aspect.
FIG. 6 is a call flow showing a hard handover with concurrent UL
synchronization in a TD-SCDMA network according to one aspect.
FIG. 7 is a call flow showing hard handover with a unique SYNC_UL
code in a TD-SCDMA network according to one aspect.
FIG. 8 is a flow chart illustrating hard handover in a TD-SCDMA
network according to one aspect.
FIG. 9 is a flow chart illustrating hard handover in a TD-SCDMA
network according to one aspect.
DETAILED DESCRIPTION
The detailed description set forth below, in connection with the
appended drawings, is intended as a description of various
configurations and is not intended to represent the only
configurations in which the concepts described herein may be
practiced. The detailed description includes specific details for
the purpose of providing a thorough understanding of the various
concepts. However, it will be apparent to those skilled in the art
that these concepts may be practiced without these specific
details. In some instances, well-known structures and components
are shown in block diagram form in order to avoid obscuring such
concepts.
Turning now to FIG. 1, a block diagram is shown illustrating an
example of a telecommunications system 100. The various concepts
presented throughout this disclosure may be implemented across a
broad variety of telecommunication systems, network architectures,
and communication standards. By way of example and without
limitation, the aspects of the present disclosure illustrated in
FIG. 1 are presented with reference to a UMTS system employing a
TD-SCDMA standard. In this example, the UMTS system includes a
(Radio Access Network) RAN 102 (e.g., UTRAN) that provides various
wireless services including telephony, video, data, messaging,
broadcasts, and/or other services. The RAN 102 may be divided into
a number of Radio Network Subsystems (RNSs), such as an RNS 107,
each controlled by a Radio Network Controller (RNC), such as an RNC
106. For clarity, only the RNC 106 and the RNS 107 are shown;
however, the RAN 102 may include any number of RNCs and RNSs in
addition to the RNC 106 and RNS 107. The RNC 106 is an apparatus
responsible for, among other things, assigning, reconfiguring and
releasing radio resources within the RNS 107. The RNC 106 may be
interconnected to other RNCs (not shown) in the RAN 102 through
various types of interfaces, such as a direct physical connection,
a virtual network, or the like, using any suitable transport
network.
The geographic region covered by the RNS 107 may be divided into a
number of cells, with a radio transceiver apparatus serving each
cell. A radio transceiver apparatus is commonly referred to as a
Node B in UMTS applications, but may also be referred to by those
skilled in the art as a Base Station (BS), a Base Transceiver
Station (BTS), a radio base station, a radio transceiver, a
transceiver function, a Basic Service Set (BSS), an Extended
Service Set (ESS), an Access Point (AP), or some other suitable
terminology. For clarity, two Node Bs 108 are shown; however, the
RNS 107 may include any number of wireless Node Bs. The Node Bs 108
provide wireless access points to a core network 104 for any number
of mobile apparatuses. Examples of a mobile apparatus include a
cellular phone, a smart phone, a Session Initiation Protocol (SIP)
phone, a laptop, a notebook, a netbook, a smartbook, a Personal
Digital Assistant (PDA), a satellite radio, a Global Positioning
System (GPS) device, a multimedia device, a video device, a digital
audio player (e.g., MP3 player), a camera, a game console, or any
other similar functioning device. The mobile apparatus is commonly
referred to as User Equipment (UE) in UMTS applications, but may
also be referred to by those skilled in the art as a mobile station
(MS), a subscriber station, a mobile unit, a subscriber unit, a
wireless unit, a remote unit, a mobile device, a wireless device, a
wireless communications device, a remote device, a mobile
subscriber station, an Access Terminal (AT), a mobile terminal, a
wireless terminal, a remote terminal, a handset, a terminal, a user
agent, a mobile client, a client, or some other suitable
terminology. For illustrative purposes, three UEs 110 are shown in
communication with the Node Bs 108. The Downlink (DL), also called
the forward link, refers to the communication link from a Node B to
a UE, and the Uplink (UL), also called the reverse link, refers to
the communication link from a UE to a Node B.
The core network 104, as shown, includes a GSM core network.
However, as those skilled in the art will recognize, the various
concepts presented throughout this disclosure may be implemented in
a RAN, or other suitable access network, to provide UEs with access
to types of core networks other than GSM networks.
In this example, the core network 104 supports circuit-switched
services with a mobile switching center (MSC) 112 and a gateway MSC
(GMSC) 114. One or more RNCs, such as the RNC 106, may be connected
to the MSC 112. The MSC 112 is an apparatus that controls call
setup, call routing, and UE mobility functions. The MSC 112 also
includes a Visitor Location Register (VLR) (not shown) that
contains subscriber-related information for the duration that a UE
is in the coverage area of the MSC 112. The GMSC 114 provides a
gateway through the MSC 112 for the UE to access a circuit-switched
network 116. The GMSC 114 includes a Home Location Register (HLR)
(not shown) containing subscriber data, such as the data reflecting
the details of the services to which a particular user has
subscribed. The HLR is also associated with an Authentication
Center (AuC) that contains subscriber-specific authentication data.
When a call is received for a particular UE, the GMSC 114 queries
the HLR to determine the UE's location and forwards the call to the
particular MSC serving that location.
The core network 104 also supports packet-data services with a
Serving GPRS Support Node (SGSN) 118 and a Gateway GPRS Support
Node (GGSN) 120. GPRS, which stands for General Packet Radio
Service, is designed to provide packet-data services at speeds
higher than those available with standard GSM circuit-switched data
services. The GGSN 120 provides a connection for the RAN 102 to a
packet-based network 122. The packet-based network 122 may be the
Internet, a private data network, or some other suitable
packet-based network. The primary function of the GGSN 120 is to
provide the UEs 110 with packet-based network connectivity. Data
packets are transferred between the GGSN 120 and the UEs 110
through the SGSN 118, which performs primarily the same functions
in the packet-based domain as the MSC 112 performs in the
circuit-switched domain.
The UMTS air interface is a spread spectrum Direct-Sequence Code
Division Multiple Access (DS-CDMA) system. The spread spectrum
DS-CDMA spreads user data over a much wider bandwidth through
multiplication by a sequence of pseudorandom bits called chips. The
TD-SCDMA standard is based on such direct sequence spread spectrum
technology and additionally calls for a Time Division Duplexing
(TDD), rather than a Frequency Division Duplexing (FDD) as used in
many FDD mode UMTS/W-CDMA systems. TDD uses the same carrier
frequency for both the Uplink (UL) and Downlink (DL) between a Node
B 108 and a UE 110, but divides uplink and downlink transmissions
into different time slots in the carrier.
FIG. 2 shows a frame structure 200 for a TD-SCDMA carrier. The
TD-SCDMA carrier, as illustrated, has a frame 202 that is 10 ms in
length. The frame 202 has two 5 ms subframes 204, and each of the
subframes 204 includes seven time slots, TS0 through TS6. The first
time slot, TS0, is usually allocated for downlink communication,
while the second time slot, TS1, is usually allocated for uplink
communication. The remaining time slots, TS2 through TS6, may be
used for either uplink or downlink, which allows for greater
flexibility during times of higher data transmission times in
either the uplink or downlink directions. A Downlink Pilot Time
Slot (DwPTS) 206 (also known as the Downlink Pilot Channel
(DwPCH)), a guard period (GP) 208, and an Uplink Pilot Time Slot
(UpPTS) 210 (also known as the uplink pilot channel (UpPCH)) are
located between TS0 and TS1. Each time slot, TS0-TS6, may allow
data transmission multiplexed on a maximum of 16 code channels.
Data transmission on a code channel includes two data portions 212
separated by a midamble 214 and followed by a Guard Period (GP)
216. The midamble 214 may be used for features, such as channel
estimation, while the GP 216 may be used to avoid inter-burst
interference.
FIG. 3 is a block diagram of a Node B 310 in communication with a
UE 350 in a RAN 300, where the RAN 300 may be the RAN 102 in FIG.
1, the Node B 310 may be the Node B 108 in FIG. 1, and the UE 350
may be the UE 110 in FIG. 1. In the downlink communication, a
transmit processor 320 may receive data from a data source 312 and
control signals from a controller/processor 340. The transmit
processor 320 provides various signal processing functions for the
data and control signals, as well as reference signals (e.g., pilot
signals). For example, the transmit processor 320 may provide
Cyclic Redundancy Check (CRC) codes for error detection, coding and
interleaving to facilitate Forward Error Correction (FEC), mapping
to signal constellations based on various modulation schemes (e.g.,
Binary Phase-Shift Keying (BPSK), Quadrature Phase-Shift Keying
(QPSK), M-Phase-Shift Keying (M-PSK), M-Quadrature Amplitude
Modulation (M-QAM), and the like), spreading with Orthogonal
Variable Spreading Factors (OVSF), and multiplying with scrambling
codes to produce a series of symbols. Channel estimates from a
channel processor 344 may be used by a controller/processor 340 to
determine the coding, modulation, spreading, and/or scrambling
schemes for the transmit processor 320. These channel estimates may
be derived from a reference signal transmitted by the UE 350 or
from feedback contained in the midamble 214 (FIG. 2) from the UE
350. The symbols generated by the transmit processor 320 are
provided to a transmit frame processor 330 to create a frame
structure. The transmit frame processor 330 creates this frame
structure by multiplexing the symbols with a midamble 214 (FIG. 2)
from the controller/processor 340, resulting in a series of frames.
The frames are then provided to a transmitter 332, which provides
various signal conditioning functions including amplifying,
filtering, and modulating the frames onto a carrier for downlink
transmission over the wireless medium through smart antennas 334.
The smart antennas 334 may be implemented with beam steering
bidirectional adaptive antenna arrays or other similar beam
technologies.
At the UE 350, a receiver 354 receives the downlink transmission
through an antenna 352 and processes the transmission to recover
the information modulated onto the carrier. The information
recovered by the receiver 354 is provided to a receive frame
processor 360, which parses each frame, and provides the midamble
214 (FIG. 2) to a channel processor 394 and the data, control, and
reference signals to a receive processor 370. The receive processor
370 then performs the inverse of the processing performed by the
transmit processor 320 in the Node B 310. More specifically, the
receive processor 370 descrambles and despreads the symbols, and
then determines the most likely signal constellation points
transmitted by the Node B 310 based on the modulation scheme. These
soft decisions may be based on channel estimates computed by the
channel processor 394. The soft decisions are then decoded and
deinterleaved to recover the data, control, and reference signals.
The CRC codes are then checked to determine whether the frames were
successfully decoded. The data carried by the successfully decoded
frames will then be provided to a data sink 372, which represents
applications running in the UE 350 and/or various user interfaces
(e.g., display). Control signals carried by successfully decoded
frames will be provided to a controller/processor 390. When frames
are unsuccessfully decoded by the receiver processor 370, the
controller/processor 390 may also use an Acknowledgement (ACK)
and/or Negative Acknowledgement (NACK) protocol to support
retransmission requests for those frames.
In the uplink, data from a data source 378 and control signals from
the controller/processor 390 are provided to a transmit processor
380. The data source 378 may represent applications running in the
UE 350 and various user interfaces (e.g., keyboard, pointing
device, track wheel, and the like). Similar to the functionality
described in connection with the downlink transmission by the Node
B 310, the transmit processor 380 provides various signal
processing functions including CRC codes, coding and interleaving
to facilitate FEC, mapping to signal constellations, spreading with
OVSFs, and scrambling to produce a series of symbols. Channel
estimates, derived by the channel processor 394 from a reference
signal transmitted by the Node B 310 or from feedback contained in
the midamble transmitted by the Node B 310, may be used to select
the appropriate coding, modulation, spreading, and/or scrambling
schemes. The symbols produced by the transmit processor 380 will be
provided to a transmit frame processor 382 to create a frame
structure. The transmit frame processor 382 creates this frame
structure by multiplexing the symbols with a midamble 214 (FIG. 2)
from the controller/processor 390, resulting in a series of frames.
The frames are then provided to a transmitter 356, which provides
various signal conditioning functions including amplification,
filtering, and modulating the frames onto a carrier for uplink
transmission over the wireless medium through the antenna 352.
The uplink transmission is processed at the Node B 310 in a manner
similar to that described in connection with the receiver function
at the UE 350. A receiver 335 receives the uplink transmission
through the smart antennas 334 and processes the transmission to
recover the information modulated onto the carrier. The information
recovered by the receiver 335 is provided to a receive frame
processor 336, which parses each frame, and provides the midamble
214 (FIG. 2) to the channel processor 344 and the data, control,
and reference signals to a receive processor 338. The receive
processor 338 performs the inverse of the processing performed by
the transmit processor 380 in the UE 350. The data and control
signals carried by the successfully decoded frames may then be
provided to a data sink 339 and the controller/processor 340,
respectively. If some of the frames were unsuccessfully decoded by
the receive processor 338, the controller/processor 340 may also
use an Acknowledgement (ACK) and/or Negative Acknowledgement (NACK)
protocol to support retransmission requests for those frames.
The controller/processors 340 and 390 may be used to direct the
operation at the Node B 310 and the UE 350, respectively. For
example, the controller/processors 340 and 390 may provide various
functions including timing, peripheral interfaces, voltage
regulation, power management, and other control functions. The
computer readable media of memories 342 and 392 may store data and
software for the Node B 310 and the UE 350, respectively. For
example, the memory 342 of the Node B 310 includes a handover
module 343, which, when executed by the controller/processor 340,
the handover module 343 configures the Node B to perform handover
procedures from the aspect of scheduling and transmission of system
messages to the UE 350 for implementing a handover from a source
cell to a target cell. A scheduler/processor 346 at the Node B 310
may be used to allocate resources to the UEs and schedule downlink
and/or uplink transmissions for the UEs not only for handovers, but
for regular communications as well.
In order to provide more capacity, the TD-SCDMA system may allow
multiple carrier signals or frequencies. Assuming that N is the
total number of carriers, the carrier frequencies may be
represented by the set {F(i), i=0, 1, . . . , N-1}, where the
carrier frequency, F(0), is the primary carrier frequency and the
rest are secondary carrier frequencies. For example, a cell can
have three carrier signals whereby the data can be transmitted on
some code channels of a time slot on one of the three carrier
signal frequencies.
FIG. 4 is a block diagram illustrating carrier frequencies 40 in a
multi-carrier TD-SCDMA communication system. The multiple carrier
frequencies include a primary carrier frequency 400 (F(0)), and two
secondary carrier frequencies 401 and 402 (F(1) and F(2)). In such
multi-carrier systems, the system overhead may be transmitted on
the first time slot (TS0) of the primary carrier frequency 400,
including the Primary Common Control Physical Channel (P-CCPCH),
the Secondary Common Control Physical Channel (S-CCPCH), the Pilot
Indicator Channel (PICH), and the like. The traffic channels may
then be carried on the remaining time slots (TS1-TS6) of the
primary carrier frequency 400 and on the secondary carrier
frequencies 401 and 402. Therefore, in such configurations, a UE
will receive system information and monitor the paging messages on
the primary carrier frequency 400 while transmitting and receiving
data on either one or all of the primary carrier frequency 400 and
the secondary carrier frequencies 401 and 402.
High Speed Downlink Packet Access (HSDPA) protocols in a TD-SCDMA
network operate on several channels including a High-Speed Shared
Control Channel (HS-SCCH), a High-Speed Physical Downlink Shared
Channel (HS-PDSCH), and a High-Speed Shared Information Channel
(HS-SICH). The HS-SCCH indicates a Modulation and Coding Scheme
(MCS), channelization codes, and time slot resource information for
data busts on the HS-PDSCH. The HS-PDSCH is a downlink channel for
the UE to receive data. The HS-SICH is an uplink channel for the UE
to send Channel Quality Indicator (CQI) reports and HARQ ACK/NACK
for HS-PDSCH transmission.
High Speed Uplink Packet Access protocols in a TD-SCDMA network
operate on several channels including an Enhanced Dedicated Channel
(E-DCH) Physical Uplink Channel (E-PUCH), an Enhanced Dedicated
Channel (E-DCH) Absolute Grant Channel (E-AGCH), and an E-DCH
Hybrid ARQ Acknowledgement Indicator Channel (E-HICH). The E-PUCH
is an uplink channel for the UE to send data. The E-AGCH is a
downlink channel for indicating the uplink absolute grant control
information. The E-HICH is a downlink channel for sending HARQ
ACK/NACK.
Hard handovers occur in TD-SCDMA networks when a UE changes both
downlink (DL) and uplink (UL) channels from a source cell (or Node
B) to a target cell (or Node B) simultaneously. In hard handovers,
the UE performs UL synchronization procedures on the Uplink Pilot
Channel (UpPCH) by sending a SYNC_UL code to the target cell and
receiving the timing adjustment on the Fast Physical Access Channel
(FPACH) from the target cell. The TD-SCDMA network signals from the
source cell (or Node B or RNC) the SYNC_UL code resources and FPACH
information for use by the UE before hard handover to a target
cell. Additionally, the TD-SCDMA network may specify an activation
time to the UE during which the hard handover occurs.
FIG. 5 is a call flow showing a hard handover in a TD-SCDMA network
according to one aspect. At time 510 a source cell 504 sends to the
UE 502 the HS-SCCH and E-AGCH. Then, at time 512 the source cell
504 sends to the UE 502 a HS-PDSCH. At time 514, the UE 502 sends
to the source cell 504 an E-PUCH. Then, at time 516 the UE 502
sends to the source cell 504 a HS-SICH. At time 518 the source cell
504 sends to the UE 502 an E-HICH. Then, at time 520, the source
cell 504 sends to the UE 502 a measurement control message. At time
522, the UE 502 returns a measurement report to the source cell
504.
At time 524 the source cell 504 sends to the UE 502 a physical
channel reconfiguration message. At time 526 the UE 502 sends a
SYNC_UL code to a target cell 506. The target cell 506 responds at
time 528 to the UE 502 with an FPACH acknowledgement. At time 530
the reconfiguration of the UE 502 for the target cell 506 is
complete and data on HSDPA and HSUPA channels resumes.
Standards currently do not clearly define how the HSPA channels
should resume or whether or not the HSPA communications should
resume after completing UL synchronization procedure, i.e.
receiving the ACK on FPACH. Moreover, SYNC_UL codes may be shared
by multiple UEs such that the target cell can not determine when a
UE has completed uplink synchronization and hard handover to the
target cell. Thus, there is a need for new post hard handover
procedures.
According to one aspect, HSPA reconfiguration occurs concurrently
with UL synchronization. Thus, HSPA may quickly resume operation
after a hard handover. Concurrent UL synchronization at a target
Node B includes allocating the UL data grant on the E-AGCH allowing
the UE to send UL data and a physical channel reconfiguration
complete message. The target Node B also allocates DL data
transmission on the HS-SCCH if DL data is pending for transmission
to the UE.
Concurrent UL synchronization occurs on a UE while monitoring the
HS-SCCH/HS-PDSCH and the E-AGCH after acquiring a DL of a target
Node B. If DL data is pending, the UE receives data on the
HS-PDSCH. According to one aspect, the data Acknowledgement (ACK)
is sent after receiving the FPACH acknowledgement. If an UL data
grant on the E-AGCH is pending, the UE transmits UL data or
messages after the UL synchronization completes.
FIG. 6 is a call flow showing a hard handover with concurrent UL
synchronization in a TD-SCDMA network according to one aspect. At
time 610 a UE 602 enters an activation time for hard handover from
a source cell (not shown) to a target cell 604. Then at time 612
the target cell 604 transmits the HS-SCCH and the E-AGCH to the UE
602. The E-AGCH may be a code corresponding to the UE. According to
one aspect, the E-AGCH is scrambled with a code having a one-to-one
correspondence with the media access control (MAC) address of the
UE 602. At time 612, the target cell 604 performs UL
synchronization procedures concurrently with HSDPA and HSUPA
transmission; and the UE 602 performs the UL synchronization
procedure concurrently with monitoring the HS-SCCH, the HS-PDSCH,
and the E-AGCH.
At time 614 the UE 602 transmits the SYNC_UL code to the target
cell 604 and at time 616 receives DL data on the HS-PDSCH.
According to one aspect, the UE 602 transmits the SYNC_UL code in a
different subframe than the target cell 604 sends the DL data on
the HS-PDSCH. At time 618 the target cell 604 transmits an
acknowledgement on the FPACH to the UE 602. The FPACH ACK signals
the UE 602 to resume transmission of the HS-SICH, the E-PUCH, and
the E-HICH.
At time 620, the UE 602 transmits a physical channel
reconfiguration complete message to the target cell 604 over the
E-PUCH and transmits uplink data. At time 622 the target cell 604
transmits a HARQ ACK on the E-HICH to the UE 602 and the UE 602
responds with a HARQ ACK on the HS-SICH at time 624.
According to another aspect, a source Node B allocates a unique
SYNC_UL code to a specific UE for hard handover. The UL
synchronization uses the unique SYNC_UL code followed by HSUPA and
HSDPA transmissions. When the target Node B receives the SYNC_UL
code, the target Node B knows the specific UE is performing a hard
handover. When a reconfiguration complete message is sent to the
target Node B, the target Node B knows the handover is
complete.
During hard handover a UE performs UL synchronization after
acquiring a DL of a target NB. Then, after receiving an
acknowledgement on the FPACH, the UE begins monitoring the HS-SCCH
and the E-AGCH.
During hard handover a target NB allocates UL data grants on the
E-AGCH for the UE to send UL data and a physical channel
reconfiguration complete message while receiving the SYNC _UL code
and sending an acknowledgement on the FPACH. According to one
aspect, a small amount of UL data grants occur periodically in each
subframe. After receiving UL data from the UE, the NB resumes HSDPA
if DL data is pending by allocating DL data to the UE on the
HS-SCCH.
FIG. 7 is a call flow showing hard handover with a unique SYNC_UL
code in a TD-SCDMA network according to one aspect. At time 710
during an activation time a UE 702 performs hard handover to a
target cell 704. At time 712 the UE 702 transmits a unique SYNC_UL
code to the target cell 704 and the target cell 704 responds with
an acknowledgement on the FPACH at time 714. After sending the
FPACH ACK, the target cell 714 resumes HSUPA operation. After
receiving the FPACH ACK at time 714, the UE 702 resumes HSDPA and
HSUPA operation. Then, at time 716 the target cell 704 transmits
the E-AGCH to the UE 702 and the UE 702 sends a reconfiguration
complete message on the E-PUCH along with pending UL data at time
718. According to one aspect, the E-AGCH is scrambled with a code
having a one-to-one correspondence with the MAC address of the UE
702. The target cell 704 resumes HSDPA operation after receiving
the first UL data at time 718.
At time 720 the target cell 704 sends a HARQ acknowledgement on the
E-HICH and at time 722 transmits the HS-SCCH. At time 724 the
target cell 704 transmits pending DL data on the HS-PDSCH to the UE
702. Then, the UE 702 transmits a HARQ acknowledgement on the
HS-SICH at time 726.
Performing post-hard handover processing according to the aspects
above allows HSPA operations to continue in the hard handover with
reduced latency.
FIG. 8 is a flow chart illustrating hard handover in a TD-SCDMA
network according to one aspect. At block 802 a UE performs uplink
synchronization with a target Node B (NB) of the wireless network.
At block 804 a UE receives an uplink grant and high speed downlink
data from the target NB before completion of the uplink
synchronization.
FIG. 9 is a flow chart illustrating hard handover in a TD-SCDMA
network according to one aspect. At block 902 a UE receives a
unique uplink synchronization from a source Node B (NB) of the
wireless network. At block 904 the UE transmits the uplink
synchronization code to a target NB of the wireless network.
Several aspects of a telecommunications system has been presented
with reference to TD-SCDMA. As those skilled in the art will
readily appreciate, various aspects described throughout this
disclosure may be extended to other telecommunication systems,
network architectures and communication standards. By way of
example, various aspects may be extended to other UMTS systems such
as W-CDMA, High Speed Downlink Packet Access (HSDPA), High Speed
Uplink Packet Access (HSUPA), High Speed Packet Access Plus (HSPA+)
and TD-CDMA. Various aspects may also be extended to systems
employing Long Term Evolution (LTE) (in FDD, TDD, or both modes),
LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), CDMA2000, Global
System for Mobile Communications (GSM), Evolution-Data Optimized
(EV-DO), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE
802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth,
and/or other suitable systems. The actual telecommunication
standard, network architecture, and/or communication standard
employed will depend on the specific application and the overall
design constraints imposed on the system.
Several processors have been described in connection with various
apparatuses and methods. These processors may be implemented using
electronic hardware, computer software, or any combination thereof.
Whether such processors are implemented as hardware or software
will depend upon the particular application and overall design
constraints imposed on the system. By way of example, a processor,
any portion of a processor, or any combination of processors
presented in this disclosure may be implemented with a
microprocessor, microcontroller, Digital Signal Processor (DSP), a
Field-Programmable Gate Array (FPGA), a Programmable Logic Device
(PLD), a state machine, gated logic, discrete hardware circuits,
and other suitable processing components configured to perform the
various functions described throughout this disclosure. The
functionality of a processor, any portion of a processor, or any
combination of processors presented in this disclosure may be
implemented with software being executed by a microprocessor,
microcontroller, DSP, or other suitable platform.
Software shall be construed broadly to mean instructions,
instruction sets, code, code segments, program code, programs,
subprograms, software modules, applications, software applications,
software packages, routines, subroutines, objects, executables,
threads of execution, procedures, functions, etc., whether referred
to as software, firmware, middleware, microcode, hardware
description language, or otherwise. The software may reside on a
computer-readable medium. A computer-readable medium may include,
by way of example, memory such as a magnetic storage device (e.g.,
hard disk, floppy disk, magnetic strip), an optical disk (e.g.,
Compact Disc (CD), Digital Versatile Disc (DVD)), a smart card, a
flash memory device (e.g., card, stick, key drive), Random Access
Memory (RAM), Read Only Memory (ROM), Programmable ROM (PROM),
Erasable PROM (EPROM), Electrically Erasable PROM (EEPROM), a
register, or a removable disk. Although memory is shown separate
from the processors in the various aspects presented throughout
this disclosure, the memory may be internal to the processors
(e.g., cache or register).
Computer-readable media may be embodied in a computer-program
product. By way of example, a computer-program product may include
a computer-readable medium in packaging materials. Those skilled in
the art will recognize how best to implement the described
functionality presented throughout this disclosure depending on the
particular application and the overall design constraints imposed
on the overall system.
It is to be understood that the specific order or hierarchy of
steps in the methods disclosed is an illustration of exemplary
processes. Based upon design preferences, it is understood that the
specific order or hierarchy of steps in the methods may be
rearranged. The accompanying method claims present elements of the
various steps in a sample order, and are not meant to be limited to
the specific order or hierarchy presented unless specifically
recited therein.
The previous description is provided to enable any person skilled
in the art to practice the various aspects described herein.
Various modifications to these aspects will be readily apparent to
those skilled in the art, and the generic principles defined herein
may be applied to other aspects. Thus, the claims are not intended
to be limited to the aspects shown herein, but is to be accorded
the full scope consistent with the language of the claims, wherein
reference to an element in the singular is not intended to mean
"one and only one" unless specifically so stated, but rather "one
or more." Unless specifically stated otherwise, the term "some"
refers to one or more. A phrase referring to "at least one of" a
list of items refers to any combination of those items, including
single members. As an example, "at least one of: a, b, or c" is
intended to cover: a; b; c; a and b; a and c; b and c; and a, b and
c. All structural and functional equivalents to the elements of the
various aspects described throughout this disclosure that are known
or later come to be known to those of ordinary skill in the art are
expressly incorporated herein by reference and are intended to be
encompassed by the claims. Moreover, nothing disclosed herein is
intended to be dedicated to the public regardless of whether such
disclosure is explicitly recited in the claims. No claim element is
to be construed under the provisions of 35 U.S.C. .sctn.112, sixth
paragraph, unless the element is expressly recited using the phrase
"means for" or, in the case of a method claim, the element is
recited using the phrase "step for."
* * * * *
References