ENHANCED SYSTEM ACQUISITION WHILE ROAMING
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and benefit of provisional patent application
number 62/128,429 filed in the United States Patent and Trademark Office on
March 4, 2015, and non-provisional patent application number 14/788,212 filed in
the United States Patent and Trademark Office on June 30, 2015, the entire
contents of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The technology discussed below relates generally to wireless communication
and, more particularly, to system acquisition while roaming in a wireless
communication network.
INTRODUCTION
[0003] Wireless communication systems are widely deployed to provide various
telecommunication services such as telephony, video, data, messaging, and
broadcasts. Many wireless communication technologies have been adopted in
various telecommunication standards to provide a common protocol that enables
different wireless devices to communicate on a municipal, national, regional, and
even global level. An example of a telecommunication standard is Long Term
Evolution (LTE). LTE is a set of enhancements to the Universal Mobile
Telecommunications System (UMTS) mobile standard promulgated by Third
Generation Partnership Project (3GPP). It is designed to better support mobile
broadband Internet access by improving spectral efficiency, lower costs, improve
services, make use of new spectrum, and better integrate with other open
standards.
[0004] However, as the demand for mobile broadband access continues to increase,
there exists a need for further improvements in LTE technology. For example, the
quality of service of voice communications utilizing the packet switched LTE
network remains less than that available in existing, circuit switched networks.
For example, 3GPP networks such as UMTS and GSM, and networks defined by
other standards bodies, such as the cdma2000 l x networks promulgated by
3GPP2, continue to be relied upon for their circuit switched voice communication
capabilities.
BRIEF SUMMARY OF SOME EXAMPLES
The following presents a simplified summary of one or more aspects of the
present disclosure, in order to provide a basic understanding of such aspects. This
summary is not an extensive overview of all contemplated features of the
disclosure, and is intended neither to identify key or critical elements of all aspects
of the disclosure nor to delineate the scope of any or all aspects of the disclosure.
Its sole purpose is to present some concepts of one or more aspects of the
disclosure in a simplified form as a prelude to the more detailed description that is
presented later.
In an aspect, the disclosure provides a method of wireless communication that
includes detecting roaming from a coverage area associated with a first public
land mobile network (PLMN) supporting hybrid voice and data to a coverage area
associated with a second PLMN without support for hybrid voice and data. The
method also includes, in response to the detecting, storing data corresponding to
the second PLMN such that the second PLMN is a registered PLMN (RPLMN).
The method also includes initiating system acquisition, wherein the system
acquisition includes searching for the RPLMN prior to searching for any other
PLMN.
In another aspect, the disclosure provides an apparatus for wireless
communication, and the apparatus includes a memory, a transceiver, and at least
one processor communicatively coupled to the memory and the at least one
processor. The at least one processor is configured for detecting roaming from a
coverage area associated with a first PLMN supporting hybrid voice and data to a
coverage area associated with a second PLMN without support for hybrid voice
and data. The at least one processor is also configured for storing, in response to
the detecting, data corresponding to the second PLMN in the memory such that
the second PLMN is an RPLMN. The at least one processor is also configured for
initiating system acquisition, wherein the system acquisition includes searching
for the RPLMN prior to searching for any other PLMN.
In yet another aspect, the disclosure provides another apparatus for wireless
communication. The apparatus includes means for detecting roaming from a
coverage area associated with a first PLMN supporting hybrid voice and data to a
coverage area associated with a second PLMN without support for hybrid voice
and data. The apparatus also includes means for storing, in response to the
detecting, data corresponding to the second PLMN such that the second PLMN is
an RPLMN. The apparatus also includes means for initiating system acquisition,
wherein the system acquisition includes searching for the RPLMN prior to
searching for any other PLMN.
[0009] In a further aspect, the disclosure provides a computer-readable medium that
includes computer-executable instructions. The computer-executable instruction
are configured for detecting roaming from a coverage area associated with a first
PLMN supporting hybrid voice and data to a coverage area associated with a
second PLMN without support for hybrid voice and data. The computerexecutable
instructions are also configured for storing, in response to the
detecting, data corresponding to the second PLMN such that the second PLMN is
an RPLMN. The computer-executable instructions are also configured for
initiating system acquisition, wherein the system acquisition comprises searching
for the RPLMN prior to searching for any other PLMN.
[0010] These and other aspects of the invention will become more fully understood
upon a review of the detailed description, which follows. Other aspects, features,
and embodiments of the present invention will become apparent to those of
ordinary skill in the art, upon reviewing the following description of specific,
exemplary embodiments of the present invention in conjunction with the
accompanying figures. While features of the present invention may be discussed
relative to certain embodiments and figures below, all embodiments of the present
invention can include one or more of the advantageous features discussed herein.
In other words, while one or more embodiments may be discussed as having
certain advantageous features, one or more of such features may also be used in
accordance with the various embodiments of the invention discussed herein. In
similar fashion, while exemplary embodiments may be discussed below as device,
system, or method embodiments it should be understood that such exemplary
embodiments can be implemented in various devices, systems, and methods.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram illustrating an example of a hardware implementation of a
user equipment (UE).
FIG. 2 is a diagram illustrating an example of a network architecture.
FIG. 3 is a diagram illustrating an example of a radio protocol architecture.
FIG. 4 is a diagram illustrating an example of a UE in communication with a
network node.
FIG. 5 is a diagram illustrating an example of various communication types.
FIG. 6 is a diagram illustrating a first example of a UE in various coverage
areas.
FIG. 7 is a diagram illustrating a second example of a UE in various coverage
areas.
FIG. 8 is a diagram illustrating an example of various methods and/or
processes operable at a UE.
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 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.
Several aspects of telecommunication systems will now be presented with
reference to various apparatus and methods. These apparatus and methods will be
described in the following detailed description and illustrated in the accompanying
drawing by various blocks, modules, components, circuits, steps, processes,
algorithms, etc. (collectively referred to as "elements"). These elements may be
implemented using electronic hardware, computer software, or any combination
thereof. Whether such elements are implemented as hardware or software depends
upon the particular application and design constraints imposed on the overall
system.
FIG. 1 is a diagram 100 illustrating an example of a hardware implementation
of a user equipment (UE) 102. In some configurations, the UE 102 may include a
user interface 112. The user interface 112 may be configured to receive one or
more inputs from a user of the UE 102. The user interface 112 may also be
configured to display information to the user of the UE 102. The user interface
112 may exchange data to and/or from the UE 102 via the bus interface 108. The
UE 102 may also include a transceiver 110. The transceiver 110 may be
configured to receive data and/or transmit data in communication with another
apparatus. The transceiver 110 provides a means for communicating with another
apparatus via a wired and/or wireless transmission medium. The transceiver 110
may be configured to perform such communications using various types of
technologies. One of ordinary skill in the art will understand that many types of
technologies to perform such communication may be used without deviating from
the scope of the present disclosure. The UE 102 may also include a memory 114,
one or more processors 104, a computer-readable medium 106, and a bus interface
108. The bus interface 108 may provide an interface between a bus 103 and the
transceiver 110. The memory 114, the one or more processors 104, the computerreadable
medium 106, and the bus interface 108 may be connected together via
the bus 103. The processor 104 may be communicatively coupled to the
transceiver 110 and/or the memory 114.
The processor 104 may include a roam detection circuit 120, a storage circuit
121, a system acquisition circuit 122, a control circuit 123, and/or other circuits
(not shown). Generally, the roam detection circuit 120, the storage circuit 121, the
system acquisition circuit 122, the control circuit 123, and/or the other circuits
(not shown) may, individually or collectively, include various hardware
components and/or software modules that can perform and/or enable any one or
more of the functions, methods, operations, processes, features and/or aspects
described herein with reference to an apparatus. The roam detection circuit 120
provides the means for detecting roaming from the coverage area associated with
the first PLMN supporting hybrid voice and data to the coverage area associated
with the second PLMN without support for hybrid voice and data. The storage
circuit 121 provides the means for storing, in response to the detection, data
corresponding to the second PLMN such that the second PLMN is the RPLMN.
The system acquisition circuit 122 provides the means for initiating system
acquisition, wherein system acquisition may include searching for the RPLMN
prior to searching for any other PLMN.
In some configurations, the control circuit 123 provides the means for
comparing information associated with the second PLMN with stored information
associated with PLMNs that support hybrid voice and data. In such
configurations, the control circuit 123 also provides the means for determining
that the second PLMN is without support for hybrid voice and data when the
information associated with the second PLMN does not match the stored
information associated with the PLMNs that support hybrid voice and data. In
some configurations, the control circuit 123 also provides the means for switching
communication from hybrid voice and data to CSFB after determining that the
second PLMN is without support for hybrid voice and data.
The foregoing description provides a non-limiting example of the processor
104 of the UE 102. Although various circuits have been described above, one of
ordinary skill in the art will understand that the processor 104 may also include
various other circuits (not shown) that are in addition and/or alternative(s) to the
aforementioned circuits 120, 121, 122, 123. Such other circuits (not shown) may
provide the means for performing any one or more of the functions, methods,
operations, processes, features and/or aspects described herein with reference to
the apparatus.
The computer-readable medium 106 includes various computer executable
instructions. The computer-executable instructions may be executed by various
hardware components (e.g., processor 104, or any one or more of its circuits 120,
121 , 122, 123) of the UE 102. The instructions may be a part of various software
programs and/or software modules. The computer-readable medium 106 may
include roam detection instructions 140, storage instructions 141 , system
acquisition instructions 142, control instructions 143, and/or other instructions
(not shown). Generally, the roam detection instructions 140, the storage
instructions 141 , the system acquisition instructions 142, the control instructions
143, and/or the other instructions (not shown) may, individually or collectively, be
configured for performing and/or enabling any one or more of the functions,
methods, operations, processes, features and/or aspects described herein with
reference to an apparatus.
The roam detection instructions 140 include computer-executable instructions
configured for detecting roaming from the coverage area associated with the first
PLMN supporting hybrid voice and data to the coverage area associated with the
second PLMN without support for hybrid voice and data. The storage instructions
141 include computer-executable instructions configured for storing, in response
to the detection, data corresponding to the second PLMN such that the second
PLMN is the RPLMN. The system acquisition instructions 142 include computerexecutable
instructions configured for initiating system acquisition, wherein
system acquisition may include searching for the RPLMN prior to searching for
any other PLMN.
[0027] In some configurations, the control instructions 143 include computerexecutable
instructions configured for comparing information associated with the
second PLMN with stored information associated with PLMNs that support
hybrid voice and data. In such configurations, the control instructions 143 also
include computer-executable instructions configured for determining that the
second PLMN is without support for hybrid voice and data when the information
associated with the second PLMN does not match the stored information
associated with the PLMNs that support hybrid voice and data. In some
configurations, the control instructions 143 also include computer-executable
instructions configured for switching communication from hybrid voice and data
to CSFB after determining that the second PLMN is without support for hybrid
voice and data.
[0028] The foregoing description provides a non-limiting example of the computerreadable
medium 106 of the UE 102. Although various computer-executable
instructions (e.g., computer-executable code) have been described above, one of
ordinary skill in the art will understand that the computer-readable medium 106
may also include various other instructions (not shown) that are in addition and/or
alternative(s) to the aforementioned computer-executable instructions 140, 141,
142, 143. Such other instructions (not shown) may include computer-executable
instructions configured for performing any one or more of the functions, methods,
processes, operations, features and/or aspects described herein with reference to
an apparatus.
[0029] The memory 114 may include various memory modules. The memory
modules may be configured to store, and have read therefrom, various values
and/or information by the processor 104, or any of the aforementioned circuits
120, 121, 122, 123. The memory modules may also be configured to store, and
have read therefrom, various values and/or information upon execution of the
computer-executable code included in the computer-readable medium 106, or any
of the aforementioned computer-executable instructions 140, 141, 142, 143.
[0030] As described above, the storage circuit 121 and/or the storage instructions 141
provide for storing certain data corresponding to the second PLMN. Such data
may include system information associated with the second PLMN and is
described in greater detail below. In some configurations, such data is stored in
the Subscriber Identity Module (SIM) module 130 of the memory 114. However,
one of ordinary skill in the art will understand that such information may
additionally or alternatively be stored in various other components without
deviating from the scope of the present disclosure.
[0031] As also described above, the control circuit 123 and/or the control instructions
143 provide for comparing information associated with the second PLMN with
stored information associated with PLMNs that support hybrid voice and data. In
some configurations, the information associated with the second PLMN is the
Mobile Country Code (MCC) associated with the second PLMN, and the
information associated with the PLMNs that support hybrid voice and data is a list
of MCCs. Such information may be stored in the MCC module 132 of the
memory 114. However, one of ordinary skill in the art will understand that such
information may additionally or alternatively be stored in various other
components without deviating from the scope of the present disclosure.
[0032] One of ordinary skill in the art will also understand that the UE 102 may
include alternative and/or additional elements without deviating from the scope of
the present disclosure. In accordance with some aspects of the present disclosure,
an element, or any portion of an element, or any combination of elements may be
implemented with a UE 102 that includes one or more processors 104. Examples
of the one or more processors 104 include microprocessors, microcontrollers,
digital signal processors (DSPs), field programmable gate arrays (FPGAs),
programmable logic devices (PLDs), state machines, gated logic, discrete
hardware circuits, and other suitable hardware configured to perform the various
functionality described throughout this disclosure. The UE 102 may be
implemented with a bus architecture, represented generally by the bus 103 and bus
interface 108. The bus 103 may include any number of interconnecting buses and
bridges depending on the specific application of the UE 102 and the overall design
constraints. The bus 103 may link together various circuits including the one or
more processors 104, the memory 114, and the computer-readable media 106. The
bus 103 may also link various other circuits, such as timing sources, peripherals,
voltage regulators, and power management circuits, which are well known in the
art.
The one or more processors 104 may be responsible for managing the bus 103
and general processing, including the execution of software stored on the
computer-readable medium 106. The software, when executed by the one or more
processors 104, causes the UE 102 to perform the various functions described
below for any one or more apparatuses. The computer-readable medium 106 may
also be used for storing data that is manipulated by the one or more processors
104 when executing software. 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 the computer-readable medium 106. The computer-readable medium 106 may
be a non-transitory computer-readable medium. A non-transitory computerreadable
medium includes, by way of example, a magnetic storage device (e.g.,
hard disk, floppy disk, magnetic strip), an optical disk (e.g., a compact disc (CD)
or a digital versatile disc (DVD)), a smart card, a flash memory device (e.g., a
card, a stick, or a key drive), a random access memory (RAM), a read only
memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM),
an electrically erasable PROM (EEPROM), a register, a removable disk, and any
other suitable medium for storing software and/or instructions that may be
accessed and read by a computer. The computer-readable medium 106 may also
include, by way of example, a carrier wave, a transmission line, and any other
suitable medium for transmitting software and/or instructions that may be
accessed and read by a computer. The computer-readable medium 106 may reside
in the UE 102, external to the UE 102, or distributed across multiple entities
including the UE 102. The computer-readable medium 106 may be embodied in a
computer program product. By way of example and not limitation, 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.
[0034] FIG. 2 is a diagram 200 illustrating a network architecture employing various
apparatuses. A non-limiting example of such a network architecture is an LTE
network architecture. The LTE network architecture may sometimes be referred to
as an Evolved Packet System (EPS). The EPS may include one or more user UEs
102, an Evolved Universal Mobile Telecommunications System (UMTS)
Terrestrial Radio Access Network (E-UTRAN) 204, an Evolved Packet Core
(EPC) 210, a Home Subscriber Server (HSS) 220, and an Operator's Internet
Protocol (IP) Services 222. The EPS can interconnect with other access networks,
but for simplicity those entities/interfaces are not shown.
[0035] The EPS provides packet-switched services; however, as those skilled in the
art will readily appreciate, various concepts presented throughout this disclosure
may be extended to networks providing circuit-switched services. For example, as
illustrated in FIG. 2, the UE 102 is being capable of utilizing a communication
link to a circuit-switched (CS) network 230. In some configurations, the UE 102
may communicate with the CS network 230 separately from its communication
with the eNB 206. In some other configurations, the serving eNB 206 may be
capable of communicating with the CS network 230 on behalf of the UE 102. The
CS network may utilize any suitable protocol or communication standard capable
of circuit-switched communication, including but not limited to a UMTS network
utilizing W-CDMA, TD-SCDMA or any other air interface; a 3GPP2 network
such as cdma2000 lx; an IEEE 802.16 WiMAX network; or any other suitable
network or combination of networks. The actual wireless communication standard
and the multiple access technology employed will depend on the specific
application and the overall design constraints imposed on the system.
[0036] The E-UTRAN 204 includes the evolved Node B (eNB) 206 and other eNBs
208. The eNB 206 provides user and control plane protocol terminations toward
the UE 102. The eNB 206 may be connected to the other eNBs 208 via an X2
interface (e.g., a backhaul). The eNB 206 may also be referred to by those skilled
in the art as a base station (BS), a base transceiver station, a radio base station, a
radio transceiver, a transceiver function, a basic service set (BSS), an extended
service set (ESS), or some other suitable terminology. The eNB 206 provides an
access point to the EPC 210 for a UE 102. Examples of UEs 102 include a cellular
phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a
personal digital assistant (PDA), a satellite radio, a global positioning system, 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 UE 102 may
also be referred to by those skilled in the art as a mobile station, 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, a mobile terminal, a wireless
terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or
some other suitable terminology.
[0037] The eNB 206 is connected by an SI interface to the EPC 210. The EPC 210
includes a Mobility Management Entity (MME) 212, other MMEs 214, a Serving
Gateway 216, and a Packet Data Network (PDN) Gateway 218. The MME 212 is
the control node that processes the signaling between the UE 102 and the EPC
210. Generally, the MME 212 provides bearer and connection management. All
user IP packets are transferred through the Serving Gateway 216, which itself is
connected to the PDN Gateway 218. The PDN Gateway 218 provides UE IP
address allocation as well as other functions. The PDN Gateway 218 is connected
to the Operator's IP Services 222. The Operator's IP Services 222 includes the
Internet, the Intranet, an IP Multimedia Subsystem (IMS), and a packet-switched
(PS) Streaming Service (PSS).
[0038] For voice communication, the UE 102 may utilize any one or more of several
schemes. For example, voice may be packetized and communicated via the EPS
by way of the IMS. As another example, voice communication may utilize circuitswitched
channels by way of the CS network 230. Depending on which network
operator the UE 102 is communicating with, different schemes for CS voice
communication may be utilized. Various non-limiting examples various
communication types, schemes, modes, operations, methods, and/or processes are
described in greater detail below (e.g., with reference to FIG. 5) and therefore will
not be repeated here.
[0039] The radio protocol architecture may take on various forms depending on the
particular application. An example for an LTE system will now be presented with
reference to FIG. 3 . FIG. 3 is a diagram 300 illustrating an example of the radio
protocol architecture for the user and control planes. The radio protocol
architecture for the UE and the eNB is shown with three layers: Layer 1, Layer 2,
and Layer 3 . Layer 1 is the lowest layer and implements various physical layer
signal processing functions. Layer 1 will be referred to herein as the physical layer
306. Layer 2 (L2 layer) 308 is above the physical layer 306 and is responsible for
the link between the UE and eNB over the physical layer 306.
In the user plane, the L2 layer 308 includes a media access control (MAC)
sublayer 310, a radio link control (RLC) sublayer 312, and a packet data
convergence protocol (PDCP) 314 sublayer, which are terminated at the eNB on
the network side. Although not shown, the UE may have several upper layers
above the L2 layer 308 including a network layer (e.g., IP layer) that is terminated
at the PDN gateway 218 (see FIG. 2) on the network side, and an application layer
that is terminated at the other end of the connection (e.g., far end UE, server, etc.).
The PDCP sublayer 314 provides multiplexing between different radio bearers
and logical channels. The PDCP sublayer 314 also provides header compression
for upper layer data packets to reduce radio transmission overhead, security by
ciphering the data packets, and handover support for UEs between eNBs. The
RLC sublayer 312 provides segmentation and reassembly of upper layer data
packets, retransmission of lost data packets, and reordering of data packets to
compensate for out-of-order reception due to hybrid automatic repeat request
(HARQ). The MAC sublayer 310 provides multiplexing between logical and
transport channels. The MAC sublayer 310 is also responsible for allocating the
various radio resources (e.g., resource blocks) in one cell among the UEs. The
MAC sublayer 310 is also responsible for HARQ operations.
In the control plane, the radio protocol architecture for the UE 102 and eNB
206 is substantially the same for the physical layer 306 and the L2 layer 308 with
the exception that there is no header compression function for the control plane.
The control plane also includes a radio resource control (RRC) sublayer 316 in
Layer 3. The RRC sublayer 316 is responsible for obtaining radio resources (i.e.,
radio bearers) and for configuring the lower layers using RRC signaling between
the eNB 206 and the UE 102.
FIG. 4 is a diagram 400 of the UE 102 in communication with a network node
(e.g., eNB 206). In the downlink (DL), upper layer packets from the core network
are provided to a controller/processor 475. The controller/processor 475
implements the functionality of the L2 layer described earlier in connection with
FIG. 3 . In the DL, the controller/processor 475 provides header compression,
ciphering, packet segmentation and reordering, multiplexing between logical and
transport channels, and radio resource allocations to the UE 102 based on various
priority metrics. The controller/processor 475 is also responsible for HARQ
operations, retransmission of lost packets, and signaling to the UE 102.
[0044] The TX processor 416 implements various signal processing functions for the
LI layer (i.e., physical layer). The signal processing functions includes coding and
interleaving to facilitate forward error correction (FEC) at the UE 102 and
mapping to signal constellations based on various modulation schemes (e.g.,
binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), Mphase-
shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)).
The coded and modulated symbols are then split into parallel streams. Each
stream is then mapped to an OFDM subcarrier, multiplexed with a reference
signal (e.g., pilot) in the time and/or frequency domain, and then combined
together using an Inverse Fast Fourier Transform (IFFT) to produce a physical
channel carrying a time domain OFDM symbol stream. The OFDM stream is
spatially precoded to produce multiple spatial streams. Channel estimates from a
channel estimator 474 may be used to determine the coding and modulation
scheme, as well as for spatial processing. The channel estimate may be derived
from a reference signal and/or channel condition feedback transmitted by the UE
102. Each spatial stream is then provided to a different antenna 420 via a separate
transmitter 418TX. Each transmitter 418TX modulates an RF carrier with a
respective spatial stream for transmission. At the UE 102, each receiver 454RX
receives a signal through its respective antenna 452. Each receiver 454RX
recovers information modulated onto an RF carrier and provides the information
to the receiver (RX) processor 456.
[0045] The RX processor 456 implements various signal processing functions of the
LI layer. The RX processor 456 performs spatial processing on the information to
recover any spatial streams destined for the UE 102. If multiple spatial streams are
destined for the UE 102, they may be combined by the RX processor 456 into a
single OFDM symbol stream. The RX processor 456 then converts the OFDM
symbol stream from the time-domain to the frequency domain using a Fast Fourier
Transform (FFT). The frequency domain signal comprises a separate OFDM
symbol stream for each subcarrier of the OFDM signal. The symbols on each
subcarrier, and the reference signal, is recovered and demodulated by determining
the most likely signal constellation points transmitted by the eNB 206. These soft
decisions may be based on channel estimates computed by the channel estimator
458. The soft decisions are then decoded and deinterleaved to recover the data and
control signals that were originally transmitted by the eNB 206 on the physical
channel. The data and control signals are then provided to the controller/processor
459.
[0046] The controller/processor 459 implements the L2 layer described earlier in
connection with FIG. 3. In the UL, the control/processor 459 provides de
multiplexing between transport and logical channels, packet reassembly,
deciphering, header decompression, control signal processing to recover upper
layer packets from the core network. The upper layer packets are then provided to
a data sink 462, which represents all the protocol layers above the L2 layer.
Various control signals may also be provided to the data sink 462 for L3
processing. The controller/processor 459 is also responsible for error detection
using an acknowledgement (ACK) and/or negative acknowledgement (NACK)
protocol to support HARQ operations.
[0047] In the uplink (UL), a data source 467 is used to provide upper layer packets to
the controller/processor 459. The data source 467 represents all protocol layers
above the L2 layer (L2). Similar to the functionality described in connection with
the DL transmission by the eNB 206, the controller/processor 459 implements the
L2 layer for the user plane and the control plane by providing header compression,
ciphering, packet segmentation and reordering, and multiplexing between logical
and transport channels based on radio resource allocations by the eNB 206. The
controller/processor 459 is also responsible for HARQ operations, retransmission
of lost packets, and signaling to the eNB 206.
[0048] Channel estimates derived by a channel estimator 458 from a reference signal
or feedback transmitted by the eNB 206 may be used by the TX processor 468 to
select the appropriate coding and modulation schemes, and to facilitate spatial
processing. The spatial streams generated by the TX processor 468 are provided to
different antenna 452 via separate transmitters 454TX. Each transmitter 454TX
modulates an RF carrier with a respective spatial stream for transmission.
[0049] The UL transmission is processed at the eNB 206 in a manner similar to that
described in connection with the receiver function at the UE 102. Each receiver
418RX receives a signal through its respective antenna 420. Each receiver 418RX
recovers information modulated onto an R carrier and provides the information
to a RX processor 470. The RX processor 470 implements the LI layer.
[0050] The controller/processor 459 implements the L2 layer described earlier in
connection with FIG. 3. In the UL, the control/processor 459 provides de
multiplexing between transport and logical channels, packet reassembly,
deciphering, header decompression, control signal processing to recover upper
layer packets from the UE 102. Upper layer packets from the controller/processor
475 may be provided to the core network. The controller/processor 459 is also
responsible for error detection using an ACK and/or NACK protocol to support
HARQ operations.
[0051] FIG. 5 is a diagram 500 illustrating an example of the UE 102 communicating
with networks supporting CSFB and/or hybrid voice and data. A first network 502
supports hybrid voice and data. (This network 502 may also support CSFB but
hybrid voice and data may be preferred over CSFB because hybrid voice and data
may provide a better user experience relative to CSFB.) Generally, the term
'hybrid voice and data' may refer to any technology that enables simultaneous
and/or concurrent communication of voice and data. A non-limiting example of
hybrid voice and data includes simultaneous voice and LTE (SVLTE) technology.
With regard to SVLTE, the UE 102 may utilize two radio circuits: one for LTE
communication, and the other for communication with the CS network 230. The
UE 102 may be enabled to simultaneously utilize both of the radio circuits to
enable the SVLTE technology. Another non-limiting example of hybrid voice and
data includes single radio LTE (SRLTE). With regard to SRLTE, the UE 102 may
be enabled to simultaneously communicate with the CS network 230 and the EPS
utilizing a single radio circuit. SRLTE may refer to a variation of SVLTE
technology. SVLTE and SRLTE, together, may sometimes be referred to as
SXLTE. One of ordinary skill in the art will understand that SVLTE, SRLTE,
SXLTE, and/or 'hybrid voice and data' may refer to any simultaneous voice and
data technology, including both single-radio and dual-radio technologies, without
deviating from the scope of the present disclosure.
[0052] If hybrid voice and data is not available to the UE 102, the UE 102 may utilize
what is sometimes referred to as circuit-switched fallback (CSFB). In CSFB, the
EPS is utilized for data communication. When a circuit-switched voice call is
desired, the UE 102 ceases the LTE communication and 'falls back' to a 3G or
other suitable circuit-switched technology for the voice call. With CSFB, data on
the LTE network and voice on the 3G network are not possible simultaneously.
[0053] A second network 504 supports CSFB without providing support for hybrid
voice and data. As illustrated in FIG. 5, hybrid voice and data enables
communication of voice or data. In CSFB, the UE 102 is not enabled to
communicate voice and data concurrently nor simultaneously. In some
configurations, the UE 102 may utilize a single communication link with a circuitswitched
network for communication of either voice or data. Such a
communication link may not exist concurrently with another communication link
that provides data or voice, respectively. In some configurations, the UE 102 may
utilize a single software stack for either voice service or data service. However, in
CSFB, the UE 102 may not utilize that single software stack for concurrent nor
simultaneous voice and data service.
[0054] To enable hybrid voice and data, the first network 502 supporting hybrid voice
and data may utilize the MME 212, which is described in greater detail above with
reference to FIG. 2 . To enable data services, the second network 504 may utilize a
Serving General Packet Radio Service (GPRS) Support Node (SGSN) 506. To
enable voice services, the second network 504 may utilize a Mobile Switching
Center (MSC) server 508. The MSC server 508 may connect to the carrier's
telephony network. To support CSFB signaling and Short Message Service (SMS)
transfer for the UE 102, the MME 212 may connect to the MSC server 508. An
SG interface 510 between the MSC server 508 and the MME 212 may enable the
UE 102 to be both CS-registered and PS-registered while on the first network 502.
The SG interface 510 may be a reference point between the MME 212 and MSC
server 508. The SG interface 510 may used for the mobility management and
paging procedures between PS domain and the CS domain. Paging messages may
be exchanged via the SG interface 510. Such paging messages may initiate the
transition from hybrid voice and data to CSFB. Such paging messages may also
initiate the transition from CSFB to hybrid voice and data.
[0055] As described in greater detail above, hybrid voice and data allows for
simultaneous and/or concurrent communication of voice and data. In some
configurations, the UE 102 may utilize a first communication link with a packetswitched
network for communication of data, and the UE 102 may utilize a
second communication link with a circuit-switched network for communication of
data. The first communication link may exist concurrently and/or simultaneously
with the second communication link. In other words, the second communication
link may be a concurrent second communication link with the first communication
link. Generally, a communication link may refer to a communication channel or
path that connects two or more communicating devices. The communication link
may provide one of many information transmission paths such as those of
terrestrial radio communications. Without deviating from the scope of the present
disclosure, the communication link may have various characteristics, such as
point-to-point, broadcast, multipoint, point-to-multipoint, uplink, downlink,
forward link, reverse link, or any other suitable characteristic(s). In some
configurations, the UE 102 may utilize a first software stack for circuit-switched
communication, such as voice service, and utilize a second software stack for
packet-switched communication, such as data service. The first software stack
may be utilized concurrently and/or simultaneously with the utilization of the
second software stack. Generally, a software stack may refer to a series of
protocols, codes, and/or instructions that can be implemented or executed by a
processor of an apparatus (e.g., the UE 102) to enable one or more functions,
operations, aspects, and/or features. The software stack may sometimes be
referred to as a protocol stack, or any other suitable term, without deviating from
the scope of the present disclosure.
[0056] FIG. 6 is a diagram 600 illustrating an example of coverage areas 601-608,
621-624 associated with various networks. Such coverage areas 601-608, 621-
624 may sometimes be referred to as cellular regions or cells. Generally, a
coverage area refers to a particular geographic region or boundary within which a
transmitter may communicate with a receiver. Although the shapes of the
coverage areas 601-608, 621-624 illustrated in FIG. 6 may appear to be relatively
homogenous (e.g., hexagonal in shape), one of ordinary skill in the art will
understand that the actual shapes of the coverage areas 601-608, 621-624 may
vary based on terrain, obstructions, and/or other various factors without deviating
from the scope of the present disclosure. In the example illustrated in FIG. 6, each
coverage area 601-608, 621-624 defines the boundaries of a particular network
node 611-618, 631-634, respectively. When the UE 102 is located within the
coverage area 601-608, 621-624 of the respective network node 611-618, 631-
634, the network node 611-618, 631-634 may communicate with the UE 102.
The network nodes 611-618, 631-634 may refer to base stations, femto cells,
home eNBs, pico cells, micro cells, macro eNB, low-power class eNBs, highpower
class eNBs, and/or any other suitable apparatus configured for
communication with the UE 102. The network nodes 611-618, 631-634 may be
configured to provide access point to the EPC 210 and/or CS network 230 for the
UEs 102 within its respective coverage area 601-608, 621-624. The network
nodes 611-618, 631-634 described herein may be associated with the networks
502, 504 also described herein. For example, some network nodes 631-634 may
be associated with the first network 502 (e.g., a network supporting hybrid voice
and data), and some other network nodes 611-618 may be associated with the
second network 504 (e.g., a network supporting CSFB without supporting hybrid
voice and data). In some circumstances, the coverage areas of some network
node(s) may overlap with the coverage areas of some other network node(s). For
example, the coverage area 623 of a first network node 633 supporting hybrid
voice and data may overlap with the coverage area 607 of a second network node
617 supporting CSFB without supporting hybrid voice and data. When the UE
102 is within both of the coverage areas 607, 623, the UE 102 may communicate
with either or both of the network nodes 617, 633.
The UE 102 may roam from one location to another location. Generally,
roaming may refer to any change in the coverage area associated with the UE 102
such that the UE 102 alters its selection of the network and/or network node with
which it communicates. For example, the UE 102 may be physically moved by the
user while walking, running, driving, flight, or any other suitable type of
movement. However, one of ordinary skill in the art will understand that physical
movement of the UE 102 is not a requirement of roaming. As mentioned above,
roaming may refer to any change in the coverage area associated with the UE 102
such that the UE 102 alters its selection of the network and/or network node with
which it communicates. For example, in some circumstances, even if the UE 102
is unmoved, the network and/or network node 633 may unexpectedly become
inoperable and thus unable to communicate with the UE 102. In such
circumstances, the coverage area 623 of the network node 633 may no longer
exist. This is a non-limiting example of a change in the coverage area associated
with the UE 102. Because the coverage area 623 of the network node 633 may no
longer exist, the UE 102 may alter its selection of the network node with which it
communicates. For example, the UE 102 may change its selection from a first
network node 633 to a second network node 617. The network nodes 611-618,
631-634 may provide access to various types of networks, including networks the
utilize technologies associated with 3G, 4G/LTE, 5G, and/or any other suitable
communication protocol and/or standard.
FIG. 7 is a diagram 700 illustrating an example of the UE 102 roaming from
the coverage area associated with the first network 502 to a coverage area
associated with the second network 504. A non-limiting example of a network
(e.g., network(s) 502, 504) is a public land mobile network (PLMN). Generally, a
PLMN is a type of network that is established and/or operated by an
administration or Recognized Operating Agency (ROA) for the purpose of
providing land mobile telecommunication services to the public. A PLMN may
provide communication services to the UE 102. A PLMN may provide service in
one or more frequency bands. A PLMN may be limited or bounded by the borders
of a country. For example, the UE 102 may subscribe to services provided by an
operator known as Verizon®. In the United States, Verizon® may have one or
more PLMNs that support hybrid voice and data. If subscribed to Verizon®, the
UE 102 can utilize hybrid voice and data while roaming in the United States.
However, in Canada, operators may not have PLMNs that support hybrid voice
and data. Accordingly, the UE 102 may not be able to utilize hybrid voice and
data while roaming in Canada and, accordingly, may have to utilize CSFB. A
country may have one or more PLMNs. A PLMN may be identified by the MCC
and/or the Mobile Network Code (MNC). Each operator providing mobile
services may have its own PLMN. One PLMN may interconnect with one or more
other PLMNs, one or more Public Switched Telephone Networks (PSTNs) for
telephone communications, and/or one or more Internet Service Providers (ISPs)
for data and intemet access. Access to the PLMN may be provided via an air
interface between various apparatuses (e.g., UE 102) and various network nodes
(e.g., one or more of the network nodes 611-618, 631-634 described above with
reference to FIG. 6).
[0059] The coverage area associated with the first network 502 (e.g., first PLMN)
may be limited to the boundaries of a first country 702. The first network 502
(e.g., first PLMN) may provide support for hybrid voice and data. (This network
502 may also support CSFB, but hybrid voice and data may be preferred over
CSFB because hybrid voice and data may provide a better user experience relative
to CSFB.) The coverage area associated with the second network 504 (e.g., second
PLMN) may be limited to the boundaries of a second country 704 (that is different
from the first country 702). The second network 504 (e.g., second PLMN) may
not provide support for hybrid voice and data. However, the second network 504
(e.g., second PLMN) may provide support for other technologies, such as CSFB.
As illustrated in FIG. 7, the UE 102 may roam from the coverage area associated
with the first network 502 (e.g., first PLMN) to a second network 504 (e.g.,
second PLMN). In other words, the UE 102 may roam from a first coverage area
that supports hybrid voice and data to a second coverage area that does not
support hybrid voice and data (but does support CSFB).
[0060] After the UE 102 roams from a first coverage area that supports hybrid voice
and data to a second coverage area that does not support hybrid voice and data
(but does support CSFB), the UE 102 initiates system acquisition. Generally,
system acquisition refers to a set of communication protocols implemented or
utilized by the UE 102 for establishing a communication session with a particular
cell, base station, network node, network (e.g., PLMN), etc. For example, a UE
102 initiating system acquisition to access an LTE network may follow a cell
search procedure which includes a series of synchronization stages by which the
UE 102 determines time and frequency parameters that are necessary for
demodulating downlink signals, for transmitting with correct timing, and for
acquiring critical system parameters. In LTE, such synchronization requirements
may include symbol timing acquisition, carrier frequency synchronization, and
sampling clock synchronization. System acquisition may also include searching
for a PLMN that supports the type of communication preferred by the UE 102. As
described in greater detail above, such types of communication may include (i)
hybrid voice and data and (ii) CSFB, wherein hybrid voice and data is preferred
over CSFB by the UE 102.
[0061] When a conventional UE roams from a first coverage area that supports hybrid
voice and data to a second coverage area that does not support hybrid voice and
data (but does support CSFB), the conventional UE will first search for a Home
PLMN (HPLMN) before searching for any other type of PLMN. Generally, a
PLMN is characterized as an HPLMN when the MCC and/or the MNC of the
PLMN match the MCC and/or the MNC of the International Mobile Subscriber
Identity (IMSI) stored on the SIM. In other words, a conventional UE will have
the highest priority associated with the HPLMN relative to any other PLMN.
Accordingly, during system acquisition, the conventional UE will first search the
HPLMN before searching any other PLMN. However, in some circumstances, the
conventional UE may not provide the fastest system acquisition possible. For
instance, the conventional UE may roam from the coverage area associated with a
first network (e.g., the HPLMN) that supports hybrid voice and data to the
coverage areas of a second network (e.g., a Visited HPLMN (VPLMN), which
may sometimes be referred to as a Roaming PLMN) that does not support hybrid
voice and data (but does support CSFB). Generally, a VPLMN may refer to a
PLMN that a UE visits after leaving its HPLMN. In such circumstances, the
conventional UE will expend time and power to first search for the HPLMN, even
though the conventional UE is no longer in the coverage area associated with the
HPLMN. After expending time and power to search for the HPLMN, the
conventional UE will terminate search for the HPLMN and, subsequently, begin
searching for another PLMN (e.g., the VPLMN). Eventually, the conventional UE
may succeed in system acquisition (e.g., of the VPLMN); however, the
conventional UE will have needlessly expended time and power searching for the
HPLMN.
[0062] In various aspects of the present disclosure, the UE 102 will not necessarily
first search for the HPLMN. Firstly, the UE 102 detects roaming from the
coverage area associated with the first network 502 (e.g., the HPLMN) providing
coverage for hybrid voice and data to the coverage area associated with the second
network (e.g., the VPLMN) that does not support hybrid voice and data (but does
support CSFB). In some configurations, the UE 102 may detect that such roaming
has occurred by: (i) comparing the information (e.g., an identifier, MCC, etc.)
associated with the VPLMN with stored information (e.g., a list of identifiers, a
list of MCC, etc.) associated with PLMNs that support hybrid voice and data, and
(ii) determining that the UE 102 has roamed to a PLMN that is without support for
the hybrid voice and data when that information (e.g., the identifier, the MCC, etc.
) associated with the VPLMN does not match the stored information (e.g., the list
of identifiers, the list of MCCs, etc.) associated with PLMNs that support hybrid
voice and data. The foregoing is a non-limiting example of a technique that can be
utilized for detecting the aforementioned roaming. One of ordinary skill in the art
will understand that the UE 102 can detect such roaming utilizing various
techniques without deviating from the scope of the present disclosure.
[0063] Subsequently, the UE 102 may store data corresponding to the second network
504 (e.g., the VPLMN) such that the second network (e.g., the VPLMN) is set as a
Registered PLMN (RPLMN). Generally, the RPLMN may refer to a PLMN for
which the UE 102 has registered or performed a registration process. A nonlimiting
example of such data is system information associated with the second
network (e.g., the VPLMN). Such information may be stored in a memory of the
UE 102 (e.g., SIM module 130 of the memory 114, as illustrated in FIG. 1). By
storing system information associated with the second network (e.g., the VPLMN)
in the memory of the UE 102, the UE 102 can initiate system acquisition using
this information even after being powered off (e.g., turned off). Storing of data for
setting the VPLMN as the RPLMN may include adjusting the priority of the
RPLMN to be higher than at least one other PLMN (e.g., the HPLMN). In some
configurations, the UE 102 may switch communication from hybrid voice and
data to CSFB after determining that the second network (e.g., the VPLMN) is
without support for hybrid voice and data.
[0064] Afterwards, the UE 102 may initiate system acquisition. According to various
aspects of the present disclosure, the system acquisition includes searching for the
RPLMN prior to searching for any other PLMN. In comparison to the
conventional UE described in greater detail above, the UE 102 searches for the
RPLMN prior to searching for any other PLMN. For example, the UE 102 does
not search for the HPLMN prior to searching for the RPLMN. In other words, the
UE 102 searches for the second network 504 (supporting CSFB but without
support for hybrid voice and data) before searching for the first network 502
(supporting hybrid voice and data). Because the UE 102 is no longer in the
coverage area associated with the first network 502 (e.g., the coverage area
associated with the HPLMN), the UE 102 does not needlessly expend time and
power to search for the first network 502 (e.g., the HPLMN). Instead, the UE 102
first searches for the second network 504 (e.g., the VPLMN, which has been set as
the RPLMN) for which the UE 102 is in its coverage area. Accordingly, under the
roaming scenario described herein, the amount of time consumed by the UE 102
to perform system acquisition is less than the amount of time consumed by a
conventional UE to perform system acquisition. In other words, the UE 102 is
enabled to perform faster system acquisition relative to a conventional UE in
certain circumstances.
[0065] FIG. 8 is a diagram 800 illustrating an example of various methods and/or
processes operable at the UE 102. In some configurations, the methods and/or
processes may be performed after the UE 102 is powered on (e.g., turned on). For
example, referring to FIG. 7, the UE 102 may be powered on (e.g., turned on)
after being moved from a first country 702 to a second country 704. In some
configurations, the methods and/or processes may be performed after the UE 102
has roamed from the coverage area associated with a first PLMN to the coverage
area associated with a second PLMN. For example, referring to FIG. 7, the UE
102 roams from the coverage area associated with the first network 502 (e.g., the
HPLMN) to the coverage area associated with the second network 504 (e.g., the
VPLMN).
[0066] At block 802, the UE 102 may compare information associated with the
PLMN (e.g., a PLMN to which the UE 102 has roamed) with stored information
associated with PLMNs that support hybrid voice and data. For example, the UE
102 may compare the MCC associated with the VPLMN with a list of MCCs
associated with the PLMNs that support hybrid voice and data. If the information
(e.g., the MCC) associated with the PLMN matches the stored information (e.g.,
the list of MCCs) associated with PLMNs that support hybrid voice and data, at
block 804, the UE 102 determines that the PLMN supports hybrid voice and data.
[0067] Alternatively, if the information associated with the PLMN does not match the
stored information associated with PLMNs that support hybrid voice and data, at
block 806, the UE 102 determines that the PLMN is without support for hybrid
voice and data. Accordingly, at block 808, the UE 102 detects roaming from a
coverage area associated with a first PLMN supporting hybrid voice and data to a
coverage area associated with a second PLMN without support for hybrid voice
and data (even though the second PLMN may provide support for CSFB). For
example, referring to FIG. 7, the UE 102 detects roaming from the coverage area
associated with the first network 502 (e.g., the HPLMN) supporting hybrid voice
and data to the coverage area associated with the second network 504 (e.g., the
VPLMN) without support for hybrid voice and data.
[0068] At block 810, in response to the detection described above, the UE 102 may
store data corresponding to the second PLMN such that the second PLMN is the
RPLMN. An example of such information is system information associated with
the second PLMN. Referring to FIG. 1, the UE 102 may store such information in
the SIM module 130 of the memory 114. As described in greater detail above, the
RPLMN may have a higher priority relative to other PLMNs (e.g., the HPLMN)
for purposes of PLMN search.
[0069] At block 812, the UE 102 may switch communication from hybrid voice and
data to CSFB after determining that the second PLMN is without support for
hybrid voice and data. Because the UE 102 has determined that the second PLMN
does not support hybrid voice and data, the UE 102 switches to CSFB, which is a
technology that is supported by the second PLMN. Various aspects pertaining to
CSFB and hybrid voice and data are described in greater detail above and
therefore will not be repeated. The UE 102 may perform the switch from hybrid
voice and data to CSFB utilizing various techniques without deviating from the
scope of the present disclosure. For example, referring to FIG. 5, the UE 102 may
utilize various signaling patterns and/or schemes involving the MME 212, SGSN
506, MSC server 508, and/or SG interface 510, which are described in greater
detail above.
[0070] At block 814, the UE 102 may initiate system acquisition, wherein the system
acquisition includes searching for the RPLMN prior to searching for any other
PLMN. Whereas a conventional UE will have needlessly expended time and
power searching for the HPLMN prior to searching any other PLMN, the UE 102
searches for the RPLMN prior to searching any other PLMN (e.g., the HPLMN).
In other words, the UE 102 does not search for the HPLMN prior to searching for
the RPLMN. For example, referring to FIG. 7, the UE 102 searches for the second
network 504 (supporting CSFB but without support for hybrid voice and data)
before searching for the first network 502 (supporting hybrid voice and data).
Because the UE 102 is no longer in the coverage area associated with the first
network 502 (e.g., the coverage area associated with the HPLMN), the UE 102
does not needlessly expend time and power to search for the first network 502
(e.g., the HPLMN). Instead, the UE 102 first searches for the second network 504
(e.g., the VPLMN, which has been set as the RPLMN). Accordingly, under the
roaming scenario described herein, the amount of time consumed by the UE 102
to perform system acquisition is less than the amount of time consumed by a
conventional UE to perform system acquisition. In other words, the UE 102 is
enabled to perform faster system acquisition relative to a conventional UE in
certain circumstances.
[0071] The methods and/or processes described with reference to FIG. 8 are provided
for illustrative purposes and are not intended to limit the scope of the present
disclosure. The methods and/or processes described with reference to FIG. 8 may
be performed in sequences different from those illustrated therein without
deviating from the scope of the present disclosure. Additionally, some or all of the
methods and/or processes described with reference to FIG. 8 may be performed
individually and/or together without deviating from the scope of the present
disclosure. 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.
[0072] Within the present disclosure, the word "exemplary" is used to mean "serving
as an example, instance, or illustration." Any implementation or aspect described
herein as "exemplary" is not necessarily to be construed as preferred or
advantageous over other aspects of the disclosure. Likewise, the term "aspects"
does not require that all aspects of the disclosure include the discussed feature,
advantage or mode of operation. The term "coupled" is used herein to refer to the
direct or indirect coupling between two objects. For example, if object A
physically touches object B, and object B touches object C, then objects A and C
may still be considered coupled to one another—even if they do not directly
physically touch each other. For instance, a first die may be coupled to a second
die in a package even though the first die is never directly physically in contact
with the second die. The terms "circuit" and "circuitry" are used broadly, and
intended to include both hardware implementations of electrical devices and
conductors that, when connected and configured, enable the performance of the
functions described in the present disclosure, without limitation as to the type of
electronic circuits, as well as software implementations of information and
instructions that, when executed by a processor, enable the performance of the
functions described in the present disclosure.
The previous description is provided to enable any person skilled in the art to
practice some 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 are 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 some
aspects described throughout this disclosure that are known or later come to be
that 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. § 112(f), 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."
CLAIMS
1. A method of wireless communication, the method comprising:
detecting roaming from a coverage area associated with a first public land
mobile network (PLMN) supporting hybrid voice and data to a coverage area
associated with a second PLMN without support for hybrid voice and data;
in response to the detecting, storing data corresponding to the second PLMN
such that the second PLMN is a registered PLMN (RPLMN); and
initiating system acquisition, wherein the system acquisition comprises
searching for the RPLMN prior to searching for any other PLMN.
2 . The method of claim 1, wherein the any other PLMN comprises a home
PLMN (HPLMN).
3. The method of claim 1, further comprising:
comparing information associated with the second PLMN with stored
information associated with PLMNs that support hybrid voice and data; and
determining that the second PLMN is without support for hybrid voice and
data when the information associated with the second PLMN does not match the
stored information associated with the PLMNs that support hybrid voice and data.
4 . The method of claim 3, wherein:
the information associated with the second PLMN comprises a mobile country
code (MCC) associated with the second PLMN; and
the information associated with PLMNs that support hybrid voice and data
comprises a list of MCCs associated with the PLMNs that support hybrid voice and
data.
5. The method of claim 3, further comprising:
switching communication from hybrid voice and data to circuit-switched
fallback (CSFB) after determining that the second PLMN is without support for
hybrid voice and data.
6. The method of claim 5, wherein:
the hybrid voice and data comprises a first communication link with a packetswitched
network and a concurrent second communication link with a circuitswitched
network; and
the CSFB comprises a single communication link with the circuit-switched
network.
7. The method of claim 5, wherein:
the hybrid voice and data comprises a first software stack for voice service and
a second software stack for concurrent data service; and
the CSFB comprises a single software stack for either voice service or data
service.
8. The method of claim 1, wherein:
the coverage area associated with the first PLMN is within a first country; and
the coverage area associated with the second PLMN is within a second
country different from the first country.
9. An apparatus for wireless communication, the apparatus comprising:
a memory;
a transceiver; and
at least one processor communicatively coupled to the memory and the
transceiver, the at least one processor configured for:
detecting roaming from a coverage area associated with a first public
land mobile network (PLMN) supporting hybrid voice and data to a coverage area
associated with a second PLMN without support for hybrid voice and data;
in response to the detecting, storing data corresponding to the second
PLMN such that the second PLMN is a registered PLMN (RPLMN); and
initiating system acquisition, wherein the system acquisition comprises
searching for the RPLMN prior to searching for any other PLMN.
10. The apparatus of claim 9, wherein the any other PLMN comprises a home
PLMN (HPLMN).
11. The apparatus of claim 9, wherein the at least one processor is further
configured for:
comparing information associated with the second PLMN with stored
information associated with PLMNs that support hybrid voice and data; and
determining that the second PLMN is without support for hybrid voice and
data when the information associated with the second PLMN does not match the
stored information associated with the PLMNs that support hybrid voice and data.
12. The apparatus of claim 11, wherein:
the information associated with the second PLMN comprises a mobile country
code (MCC) associated with the second PLMN; and
the information associated with PLMNs that support hybrid voice and data
comprises a list of MCCs associated with the PLMNs that support hybrid voice and
data.
13. The apparatus of claim 11, wherein the at least one processor is further
configured for:
determining to switch communication from hybrid voice and data to circuitswitched
fallback (CSFB) after determining that the second PLMN is without support
for hybrid voice and data.
14. The apparatus of claim 13, wherein:
the hybrid voice and data comprises a first communication link with a packetswitched
network and a concurrent second communication link with a circuitswitched
network; and
the CSFB comprises a single communication link with the circuit-switched
network.
15. The apparatus of claim 13, wherein:
the hybrid voice and data comprises a first software stack for voice service and
a second software stack for concurrent data service; and
the CSFB comprises a single software stack for either voice service or data
service.
16. The apparatus of claim 9, wherein:
the coverage area associated with the first PLMN is within a first country; and
the coverage area associated with the second PLMN is within a second
country different from the first country.
17. An apparatus for wireless communication, the apparatus comprising:
means for detecting roaming from a coverage area associated with a first
public land mobile network (PLMN) supporting hybrid voice and data to a coverage
area associated with a second PLMN without support for hybrid voice and data;
means for storing, in response to the detecting, data corresponding to the
second PLMN such that the second PLMN is a registered PLMN (RPLMN); and
means for initiating system acquisition, wherein the system acquisition
comprises searching for the RPLMN prior to searching for any other PLMN.
18. The apparatus of claim 17, wherein the any other PLMN comprises a home
PLMN (HPLMN).
19. The apparatus of claim 17, further comprising:
means for comparing information associated with the second PLMN with
stored information associated with PLMNs that support hybrid voice and data; and
means for determining that the second PLMN is without support for hybrid
voice and data when the information associated with the second PLMN does not
match the stored information associated with the PLMNs that support hybrid voice
and data.
20. The apparatus of claim 19, further comprising:
means for switching communication from hybrid voice and data to circuitswitched
fallback (CSFB) after determining that the second PLMN is without support
for hybrid voice and data.
2 1. The apparatus of claim 20, wherein:
the hybrid voice and data comprises a first communication link with a packetswitched
network and a concurrent second communication link with a circuitswitched
network; and
the CSFB comprises a single communication link with the circuit-switched
network.
22. The apparatus of claim 20, wherein:
the hybrid voice and data comprises a first software stack for voice service and
a second software stack for concurrent data service; and
the CSFB comprises a single software stack for either voice service or data
service.
23. The apparatus of claim 17, wherein:
the coverage area associated with the first PLMN is within a first country; and
the coverage area associated with the second PLMN is within a second
country different from the first country.
24. A computer-readable medium comprising computer-executable instructions
configured for:
detecting roaming from a coverage area associated with a first public land
mobile network (PLMN) supporting hybrid voice and data to a coverage area
associated with a second PLMN without support for hybrid voice and data;
in response to the detecting, storing data corresponding to the second PLMN
such that the second PLMN is a registered PLMN (RPLMN); and
initiating system acquisition, wherein the system acquisition comprises
searching for the RPLMN prior to searching for any other PLMN.
25. The computer-readable medium of claim 24, wherein the any other PLMN
comprises a home PLMN (HPLMN).
26. The computer-readable medium of claim 24, wherein the computer-executable
instructions are further configured for:
comparing information associated with the second PLMN with stored
information associated with PLMNs that support hybrid voice and data; and
determining that the second PLMN is without support for hybrid voice and
data when the information associated with the second PLMN does not match the
stored information associated with the PLMNs that support hybrid voice and data.
27. The computer-readable medium of claim 24, wherein the computer-executable
instructions are further configured for:
switching communication from hybrid voice and data to circuit-switched
fallback (CSFB) after determining that the second PLMN is without support for
hybrid voice and data.
28. The computer-readable medium of claim 27, wherein:
the hybrid voice and data comprises a first communication link with a packetswitched
network and a concurrent second communication link with a circuitswitched
network; and
the CSFB comprises a single communication link with the circuit-switched
network.
29. The computer-readable medium of claim 27, wherein:
the hybrid voice and data comprises a first software stack for voice service and
a second software stack for concurrent data service; and
the CSFB comprises a single software stack for either voice service or data
service.
30. The computer-readable medium of claim 24, wherein:
the coverage area associated with the first PLMN is within a first country; and
the coverage area associated with the second PLMN is within a second
country different from the first country.