Note: Descriptions are shown in the official language in which they were submitted.
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Method and Device for Assessing Cell Failure Based on Non-Acquisition of
System Information
Field
[0001] The application relates to methods and devices for assessing cell
failure.
Background
[0002] UMTS (Universal Mobile Telecommunications System) uses a number of
physical channels on to which data is mapped via transport channels, onto
which in turn
logical channels are mapped. A number of physical channels exist in the
downlink, i.e.
from the network towards the UEs (user equipments), providing data which
enables
detection, synchronisation, and acquisition of basic system information as
well as data
transfer when data is mapped for UE reception. These channels include amongst
others
the Primary Common Pilot Channel (P-CPICH) and Primary Common Control Physical
Channel (Primary CCPCH or PCCPCH).
[0003] The Primary Common Pilot Channel is transmitted in the downlink by the
Node B to the entire cell coverage area, and uses a fixed rate and
channelization code
across the network. This is used by the UEs within the network to identify of
the
Primary Scrambling Code used for scrambling Primary Common Control Physical
Channel (PCCPCH) transmissions from the Node B. In addition the CPICH enables
phase and power estimations to be made.
[0004] The Primary CCPCH is a fixed rate downlink physical channel used to
carry the BCH (broadcast channel) transport channel, onto which the BCCH
(broadcast
control channel) logical channel is mapped. This logical channel carries the
System
Information for the cell which includes Core Network (CN), Radio Network and
cell
specific parameters to enable the UE to access the cell for service.
[0005] UMTS RRC (radio resource control) protocol [TS25.331] (see for example
TS25.331 v 10.1.0 Radio Resource Control (RRC); Protocol specification
(Release-10)
publication date (2010-09), hereby incorporated by reference in its entirety)
consists of 4
RRC connected mode states, CELL_DCH, CELL_FACH, CELL_PCH and URA_PCH
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states. In each of these states a number of measurements and procedures are
defined
within the GPP procedures.
[0006] Some of these procedures relate to handling mobility of the UE through
the UTRAN (UMTS Terrestrial Radio Access Network). This is when the UE moves
and
passes across a cell of the UMTS technology whilst in RRC connected mode [as
defined in TS25.331]. The UTRAN configures the UE to perform specific
measurements and based on these, defined RRC procedures determine how the UE
moves in a reliable manner to neighbouring cells whilst maintaining a
connection
between the UE and the network. In some RRC states (specifically CELL_FACH,
CELL_PCH or URA PCH) i.e. those without a dedicated transport channel, the UE
performs its own mobility procedures that are based on the measurements
performed
and in accordance with the measurement configuration setup by the UTRAN from
the
serving RNC (radio network controller), the UE decides when coverage of the
existing
serving cell is not good enough and when a new neighbouring cell has achieved
a level
whereby it may be chosen to be the new serving cell. This process is known as
reselection. The UE evaluation process is defined in [TS25.304] (see, for
example
TS25.304 v 9.3 User Equipment (UE) procedures in idle mode and procedures for
cell
reselection in connected mode (Release-9) publication date (2010-09), hereby
incorporated by reference in its entirety) whereby using the measured
reselection
criteria a new cell is selected according to the configured radio
measurements. In other
RRC states, for example CELL_DCH, the network initiates and controls if and
when the
mobile station changes cells by way of a handover.
[0007] The UE measurement and reselection performance criteria are defined in
[TS25.133] (see for example TS25.133 v 9.4.0 Requirements for support of radio
resource management (FDD) (Release-9) publication date (2010-09), hereby
incorporated by reference in its entirety) where associated measurement and
processing performance attributes are defined with a view to ensuring a
minimum level
of performance for the reselection behaviour of the UE thereby guaranteeing
the UE
and associated user a reliable level of performance.
[0008] In CELL_FACH state [TS25.133 section 5.5.2] defines that the
measurements CPICH Ec/lo and CPICH RSCP (received signal code power) shall be
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used for cell reselection to another FDD (frequency division duplexing) cell,
PCCPCH
RSCP shall be used for cell reselection to a TDD (time division duplexing)
cell and GSM
carrier RSSI (received signal strength indication) shall be used for cell
reselection to a
GSM cell.
[0009] The UE also uses these measurements to determine whether the cell
selection criteria (S criteria) [defined in TS25.304] are achieved. In one
aspect should
the UE lose the radio coverage of the serving cell, specific measurement
behaviour and
associated performance is defined in [25.133 section 5.5.2.3], whereby once
the UE
detects that the S criteria are not fulfilled it should continue to assess the
current cell
radio measurements whilst also searching for a neighbour cell as indicated in
the
received measurement control message. If for 4 seconds the UE fails to find
any new
suitable cell it considers itself "out of service area". At this point the UE
initiates the cell
selection procedure for the selected PLMN, namely the current registered PLMN,
in
order to locate, camp on and establish a new connection.
[0010] The UE as part of the cell selection behaviour that occurs after the 4
seconds referred to above will initially use any previously stored information
by
performing the "stored information cell selection" procedure as defined in
[TS25.304]
then if this should fail then the UE will adopt the "initial cell selection"
procedure also as
defined in [TS25.304].
[0011] When a suitable cell is selected and if the UE considers itself to be
"Out of
Service Area" whilst it is selecting the cell then the behaviour, in the case
the selected
cell is a 3G UTRAN cell, to the UE sends an RRC: Cell Update message with a
cell
update cause set to "re-entered service area", as defined in [TS25.331 ].
[0012] As can be envisaged from the above description for a UE which is in a
cell
that has failed then the time to detect when "Out of Service Area" has
occurred and then
to subsequently locate and camp on a new cell will exceed 4 seconds. In
general the
UE needs to first detect that the condition for triggering the "Out of Service
Area"
evaluation period and then once this occurs it needs continue to monitor the
cell
measurements and evaluate whether the S criteria continues to not be met for 4
seconds before declaring the "Out of Service Area" condition. Also during this
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continuous 4 second evaluation period the UE is expected to scan the
configured
neighbouring cells in order to find a suitable cell that it may reselect to.
[0013] If no suitable cell is found this condition is confirmed and the UE
determines that it is "Out of Service Area" after which it will initiate a
cell selection
procedure according to [TS25.304] to find a suitable cell on which to camp.
[0014] The process described above is specifically for the UE behaviour in RRC
state CELL_FACH, however similar behaviour is present for other RRC states.
[0015] For example in CELL_PCH and URA PCH states, the S criteria is
evaluated for the specified number of DRX (discontinuous reception) cycles
with the
associated degree of measurement filtering [25.133]. If however, after this
evaluation
the serving cell is found to not satisfy the selection criteria S then the UE
will initiate
checking the neighbour cells for 12 seconds. If no neighbour cells are
determined to be
suitable then the UE considers itself to be "Out of Service Area" and will
initiate cell
selection procedures.
[0016] Also if during a state transition from CELL_DCH to CELL_FACH,
CELL PCH or URA PCH the UE is unable to find a cell then the UE determines it
is
"Out of Service Area".
Summary
[0017] According to a broad aspect, the disclosure provides a method in a user
equipment, the method comprising: assessing whether or not a cell has failed
as a
function of whether, upon determining that system information needs to be
acquired, the
system information is acquired or not within a defined time period.
[0018] Another broad aspect provides a user equipment configured to implement
the method summarized above, or any other method described or claimed herein.
[0019] Another broad aspect provides a computer storage medium having
computer executable instructions stored thereon that, when executed by a user
equipment, cause the user equipment to perform the method summarized above, or
any
other method described or claimed herein.
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Brief Description of the Drawings
[0020] Figure 1 is a flowchart of a method of accessing a cell as a failed
cell
based on non-acquisition of system information;
[0021] Figure 2 is a flowchart of another method of accessing a cell as a
failed
5 cell based on non-acquisition of system information;
[0022] Figure 3 is a flowchart of a method of attempting to camp on cells
following assessing a serving cell to have failed based on non-acquisition of
system
information;
[0023] Figure 4 is a block diagram of a user equipment; and
[0024] Figure 5 is a block diagram of a mobile station.
Detailed Description
[0025] It should be understood at the outset that although illustrative
implementations of one or more embodiments of the present disclosure are
provided
below, the disclosed systems and/or methods may be implemented using any
number
of techniques, whether or not currently known or in existence. The disclosure
should in
no way be limited to the illustrative implementations, drawings, and
techniques
illustrated below, including the exemplary designs and implementations
illustrated and
described herein, but may be modified within the scope of the appended claims
along
with their full scope of equivalents.
[0026] The process described above for CELL_FACH takes more than 4 seconds
and results in an interruption to any ongoing data session that the UE may
have been
undertaking during the CELL_FACH connection to the failed UTRA cell. The
similar
process for CELL_PCH and URA_PCH takes more than 12 seconds.
[0027] Taking more than 4 seconds, or more than 12 seconds as the case may
be, to determine whether to a serving cell is available may not be optimum in
terms of
discovering an available cell from which to continue service, in this case of
no coverage.
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[0028] Procedures are provided that may reduce the disruption to the ongoing
connection between the UE and the network either for the case of a failed cell
or in the
case of loss of serving cell coverage and provide mechanisms for selecting a
new cell.
The mechanism may result in the selection of a new cell more quickly than
would be the
case if the UE waited for the standardised delay associated with the "Out of
Service
Area" determination [25.133] in order to continue the ongoing data connection.
In some
embodiments, these procedures are applied while in a connected mode state
other than
CELL_DCH.
[0029] A method of assessing a cell to be a failed cell is provided. This
method
can be applied in respect of the current serving cell, or in respect of
another cell such as
a neighbour cell, for example a neighbour cell that has been configured in the
sense
that the UE has been instructed to perform measurements for the neighbour
cell.
[0030] The method of assessing cell failure is provided that is based on non-
acquisition of system information. With reference to Figure 1, the method
involves
assessing whether or not a cell has failed as a function of whether, upon
determining
that system information needs to be acquired, the system information is
acquired or not
within a defined time period, at block 1-1.
[0031] For the purpose of this description, a 'failed" cell is a cell that is
assessed
as such based on the non-acquisition of system information. Such a cell may be
a cell
within which the base station has physically failed, or a cell for which the
UE has
become out of coverage of the base station of the cell.
[0032] There are various instances in which the UE may determine that system
information needs to be acquired. For the serving cell, the UE may need to
update
system information because its current information has expired. The UE may
need to
update system information because the network has notified the UE that the
system
information has changed. For neighbour cells, the UE may attempt to acquire
system
information, for example, when attempting to perform cell reselection.
[0033] In some embodiments, the method involves upon determining that system
information needs to be acquired, starting a timer. If the system information
is acquired,
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the UE cancels the timer. The UE then assesses whether the cell has failed or
not as a
function of whether the timer expires. In particular, if the timer does
expire, then the cell
access the cell as a failed cell. With reference to Figure 2, a particular
example
implementation will now be described. This method involves determining that
system
information needs to be acquired in block 2-1; starting a timer at block 2-2;
if system
information is acquired (yes path block 2-3), cancelling the timer at block 2-
4; if the
system information is not acquired before the timer expires (no path block 2-
3),
assessing the cell as failed at block 2-5.
[0034] In some embodiments, the timer has a timeout value that differs for
different types of system information to be acquired.
[0035] In a first specific example, if the UE is attempting to acquire the
Master
Information Block (MIB) and the Scheduling Blocks (SBs) then the UE starts a
timer
which is set to a first timeout value, for example two seconds, and tries to
acquire these
blocks. If the UE is unable to locate and read the MIB and SBs before the
timer expires,
the system information is considered to be in error UE assesses cell failure
to have
occurred.
[0036] In a second specific example, if the UE is attempting to acquire the
System Information Blocks (SIBs) then the UE starts a timer which is set to a
second
timeout value, for example 15 seconds, and tries to acquire these blocks. In
one
example the System Information Blocks are the required System Information
Blocks as
indicated in the MIB. In another example the System Information Blocks if not
received
before in that cell are System Information Block Type 1, System Information
Block Type
3, System Information Block Type 5, System Information Block Type 7 and System
Information Block Type 11. If the UE is unable to locate and read the
determined SIBs
before the timer expires, the system information is considered to be in error
and the UE
assesses cell failure to have occurred.
Follow-on Behaviour
[0037] In some embodiments, upon assessing a cell (the serving cell or a
neighbour cell) to have failed using this mechanism, the UE then bars this
cell (i.e.
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does not attempt to camp on the cell) for a defined period, for example a
period Tbarred
(as defined in TS25.304) which is set to the minimum value of 10 seconds.
Then,
whenever the UE attempts to camp on another cell, for example as part of a
reselection
process, the UE refrains from attempting to acquire a given cell so long as
the cell is
barred. Advantageously, removing a cell from consideration may reduce battery
drain
compared to repeatedly measuring the cell and trying to read its PCCPCH.
[0038] For the purpose of this description, a UE is camped on a cell after the
UE
has completed the cell selection or a cell reselection process and has chosen
a cell; at
that point the UE monitors system information and (in most cases) paging
information.
[0039] In order to successfully camp on a cell, for example as part of a cell
selection or cell reselection process, various steps are taken. The process of
"attempting to camp" on a cell involves performing one or more of the steps
necessary
to successfully camp on the cell. If less than all of the necessary steps are
able to be
successfully completed, then the attempt has failed. A specific example of the
steps
involved in attempting to camp on a cell can be found in TS25.304 but it is to
be clearly
understood that the disclosure is not limited to this example.
[0040] If the serving cell is assessed to have failed, the UE can then attempt
to
camp on another candidate cell. A cell is a candidate cell if it satisfies a
set of basic
criteria. These may for example be based on set minimum values for
measurements
taken in each cell. Satisfaction of the S-criteria is a specific example. In a
specific
example, the UE attempts to camp on a configured neighbour cell that is not
barred.
For example, this might be the next neighbour cell ranked according to a
ranking
criterion, for example based on the measurements of neighbour cell using
serving cell
measurements as a reference point.
[0041] In a first specific example, after assessing failure of the serving
cell using
this mechanism, the UE attempts a targeted search to identify and camp on a
cell from
which to continue the service. In an example of a targeted search the UE
utilizes
predetermined knowledge of the PLMN and its configuration of frequencies,
Radio
Access Technologies e.g. UMTS, GERAN, CDMA2000 etc. possibly in combination
with
any neighbour cell information stored from the previously accessed cells on
the PLMN.
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[0042] In a second specific example, after assessing failure of the serving
cell
using this mechanism the UE attempts to camp on a candidate neighbour cell
that has
not been barred. Upon failure to camp on such a cell, the UE attempts a
targeted
search to identify and camp on a cell from which to continue the service. An
example
of a targeted search is given above.
[0043] In a third example, after assessing failure of the serving cell using
this
mechanism the UE attempts to camp on a candidate neighbour cell that has not
been
barred, based on previous cell measurements; these may be ranked according to
the
measurements. The UE may attempt to camp on the candidate neighbour cells in
order of their rankings. Note that the process of attempting to camp on these
cells may
result in one or more of them being barred due to non-acquisition of system
information.
If no suitable cell is found, then if there are neighbour cells that are not
considered to be
barred, then measure them for a period (e.g. 4s in Cell_FACH, 12s in Idle,
Cell _PCH or
URA_PCH) and attempt to camp on a candidate cell, for example the best cell in
accordance with the measurements, if one becomes available, e.g. by getting
stronger
and so satisfy the S criteria. If after the period still no suitable cell is
found, or there are
no neighbour cells that are not considered to be barred, then start searching
for a cell
more widely than amongst just the neighbour cells.
[0044] With reference to Figure 3, the following is a specific example of a
process
flow:
on an ongoing basis perform measurements for configured neighbour
cells, and maintain a rank for the configured neighbour cells according to a
ranking
criterion based on the measurements (block 3-1);
upon attempting to read system information of a cell (which might be the
serving cell or neighbour cell) perform failure assessment in respect of the
cell based on
non-acquisition of system information (block 3-2);
upon failure of a cell based on non-acquisition of system information,
mark that cell as a barred cell for a defined period of time following
detection of the
failure (block 3-3);
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when performing cell reselection, consider only cells that are not barred
(block 3-4).
[0045] In some implementations, the process flow continues as follows:
if the serving cell fails, attempting to camp on a candidate neighbour cell
5 that has not been barred, for example the highest ranked candidate neighbour
cell
(block 3-5).
[0046] In some implementations, the process flow continues as follows:
if no cell has yet been camped on after performing block 3-5, perform a
targeted search (block 3-6).
10 [0047] In another embodiment, rather than executing a targeted search
following
block 3-5, if there are neighbour cells that are not considered to be barred,
then the UE
measures them for a defined period (e.g. 4s in Cell_FACH, 12s in Idle,
Cell_PCH or
URA_PCH) and attempts to camp on a candidate neighbour cell if there is one.
Then, if
after the period still no neighbour cell is suitable, or there are no
neighbour cells that are
not considered to be barred, then start searching for a cell in a targeted
manner more
widely than amongst just the neighbour cells.
[0048] It will be appreciated that that any module, component, or device
exemplified herein that executes instructions may include or otherwise have
access to
computer readable storage medium or media for storage of information, such as
computer readable instructions, data structures, program modules, or other
data. A
non-exhaustive list of examples of computer readable storage media include
magnetic
cassettes, magnetic tape, magnetic disk storage or other magnetic storage
devices,
optical disks such as CD-ROM, digital versatile disks (DVD) or other optical
storage,
volatile and non-volatile, removable and non-removable media implemented in
any
method or technology, RAM, ROM, EEPROM, flash memory or other memory
technology. Any such computer storage media may be part of the device or
accessible
or connectable thereto. Any application or module herein described may be
implemented using computer readable/executable instructions that may be stored
or
otherwise held by such computer readable storage media.
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[0049] Referring to Figure 4, shown is a block diagram of a UE generally
indicated at 10. The UE has at least one antenna 12. The UE has at least one
wireless
access radio 14 and a processor 16. The UE has a CEFBNSI (cell failure
assessor
based on non-acquisition of system information) 18. The CFBNSI functions to
access
cell failure based on non-acquisition of system information, or example, using
one of the
methods described above. The CFBNSI may be implemented as software in
combination with appropriate hardware for running the software, hardware,
firmware, or
a combination thereof. The UE may have other components, not shown in the
interest
of brevity.
Another Mobile Device
[0050] Referring now to Figure 5, shown is a block diagram of a mobile device
100 that is an example of a user equipment that may implement any of the
methods
described herein. The mobile device 100 is shown with specific components for
implementing features similar to those of the mobile device 30 shown in Figure
1. It is
to be understood that the mobile device 100 is shown with very specific
details for
exemplary purposes only.
[0051] The mobile device 100 has a housing that may be elongated vertically,
or
may take on other sizes and shapes (including clamshell housing structures).
The
keyboard 114 may include a mode selection key, or other hardware or software
for
switching between text entry and telephony entry. Alternatively, the mobile
device 100
may have a housing that does not take on other sizes and shapes.
[0052] A microprocessor 128 is shown schematically as coupled between a
keyboard 114 and a display 126. The microprocessor 128 is a type of processor
with
features similar to those of the processor 32 of the mobile device 30 shown in
Figure 1.
The microprocessor 128 controls operation of the display 126, as well as
overall
operation of the mobile device 100, in response to actuation of keys on the
keyboard
114 by a user.
[0053] In addition to the microprocessor 128, other parts of the mobile device
100
are shown schematically. These include: a communications subsystem 170; a
short-
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range communications subsystem 102; the keyboard 114 and the display 126,
along
with other input/output devices including a set of LEDs 104, a set of
auxiliary I/O
devices 106, a serial port 108, a speaker 111 and a microphone 112; as well as
memory devices including a flash memory 116 and a Random Access Memory (RAM)
118; and various other device subsystems 120. The mobile device 100 may have a
battery 121 to power the active elements of the mobile device 100. The mobile
device
100 is in some embodiments a two-way radio frequency (RF) communication device
having voice and data communication capabilities. In addition, the mobile
device 100 in
some embodiments has the capability to communicate with other computer systems
via
the Internet.
[0054] Operating system software executed by the microprocessor 128 is in
some embodiments stored in a persistent store, such as the flash memory 116,
but may
be stored in other types of memory devices, such as a read only memory (ROM)
or
similar storage element. In addition, system software, specific device
applications, or
parts thereof, may be temporarily loaded into a volatile store, such as the
RAM 118.
Communication signals received by the mobile device 100 may also be stored to
the
RAM 118.
[0055] The microprocessor 128, in addition to its operating system functions,
enables execution of software applications on the mobile device 100. A
predetermined
set of software applications that control basic device operations, such as a
voice
communications module 130A and a data communications module 1306, may be
installed on the mobile device 100 during manufacture. In addition, a personal
information manager (PIM) application module 130C may also be installed on the
mobile device 100 during manufacture. The PIM application is in some
embodiments
capable of organizing and managing data items, such as e-mail, calendar
events, voice
mails, appointments, and task items. The PIM application is also in some
embodiments
capable of sending and receiving data items via a wireless network 110. In
some
embodiments, the data items managed by the PIM application are seamlessly
integrated, synchronized and updated via the wireless network 110 with the
device
user's corresponding data items stored or associated with a host computer
system.
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[0056] Additional software modules, illustrated as another software module
130N,
may be installed during manufacture. The software modules may, for example,
include
one or modules that control the execution of the methods of assessing the
failure of
cells based on non-acquisition of system information, described previously.
Note that
the implementations described with reference to Figure 5 are very specific for
exemplary purposes. For example, alternative implementations are possible in
which
the method of assessing the failure of cells based on non-acquisition of
system
information is not implemented as software and stored on the flash memory 116.
More
generally, the methods may be implemented as software running on appropriate
hardware, hardware, firmware, or any appropriate combination thereof.
[0057] Communication functions, including data and voice communications, are
performed through the communication subsystem 170, and possibly through the
short-
range communications subsystem 102. The communication subsystem 170 includes a
receiver 150, a transmitter 152, a GPS receiver 162, and one or more antennas,
illustrated as a receive antenna 154, a transmit antenna 156, and a GPS
antenna 164.
In addition, the communication subsystem 170 also includes a processing
module, such
as a digital signal processor (DSP) 158, and local oscillators (LOs) 160. The
communication subsystem 170 has features similar to those of the wireless
access
radio 31 of the mobile device 30 shown in Figure 1.
[0058] The specific design and implementation of the communication subsystem
170 is dependent upon the communication network in which the mobile device 100
is
intended to operate. For example, the communication subsystem 170 of the
mobile
device 100 may be designed to operate with the MobitexTM, DataTACTM or General
Packet Radio Service (GPRS) mobile data communication networks and also
designed
to operate with any of a variety of voice communication networks, such as
Advanced
Mobile Phone Service (AMPS), Time Division Multiple Access (TDMA), Code
Division
Multiple Access (CDMA), Personal Communications Service (PCS), Global System
for
Mobile Communications (GSM), etc. Examples of CDMA include 1X and 1x EV-DO.
The communication subsystem 170 may also be designed to operate with an 802.11
Wi-Fi network, and/or an 802.16 WiMAX network. Other types of data and voice
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networks, both separate and integrated, may also be utilized with the mobile
device
100.
[0059] Network access may vary depending upon the type of communication
system. For example, in the MobitexTM and DataTACTM networks, mobile devices
are
registered on the network using a unique Personal Identification Number (PIN)
associated with each device. In GPRS networks, however, network access is
typically
associated with a subscriber or user of a device. A GPRS device therefore
typically has
a subscriber identity module, commonly referred to as a Subscriber Identity
Module
(SIM) card, in order to operate on a GPRS network.
[0060] When network registration or activation procedures have been completed,
the mobile device 100 may send and receive communication signals over the
communication network 110. Signals received from the communication network 110
by
the receive antenna 154 are routed to the receiver 150, which provides for
signal
amplification, frequency down conversion, filtering, channel selection, etc.,
and may
also provide analog to digital conversion. Analog-to-digital conversion of the
received
signal allows the DSP 158 to perform more complex communication functions,
such as
demodulation and decoding. In a similar manner, signals to be transmitted to
the
network 110 are processed (e.g., modulated and encoded) by the DSP 158 and are
then provided to the transmitter 152 for digital to analog conversion,
frequency up
conversion, filtering, amplification and transmission to the communication
network 110
(or networks) via the transmit antenna 156.
[0061] In addition to processing communication signals, the DSP 158 provides
for
control of the receiver 150, the transmitter 152, and the GPS receiver 162.
For example,
gains applied to communication signals in the receiver 150 and the transmitter
152 may
be adaptively controlled through automatic gain control algorithms implemented
in the
DSP 158.
[0062] In a data communication mode, a received signal, such as a text message
or web page download, is processed by the communication subsystem 170 and is
input
to the microprocessor 128. The received signal is then further processed by
the
microprocessor 128 for an output to the display 126, or alternatively to some
other
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auxiliary I/O devices 106. A device user may also compose data items, such as
e-mail
messages, using the keyboard 114 and/or some other auxiliary I/O device 106,
such as
a touchpad, a rocker switch, a thumb-wheel, or some other type of input
device. The
composed data items may then be transmitted over the communication network 110
via
5 the communication subsystem 170.
[0063] In a voice communication mode, overall operation of the device is
substantially similar to the data communication mode, except that received
signals are
output to a speaker 111, and signals for transmission are generated by a
microphone
112. Alternative voice or audio I/O subsystems, such as a voice message
recording
10 subsystem, may also be implemented on the mobile device 100. In addition,
the display
126 may also be utilized in voice communication mode, for example, to display
the
identity of a calling party, the duration of a voice call, or other voice call
related
information.
[0064] Location determination using GPS technology involves receiving GPS
15 signals from GPS satellites 166 on the antenna 164. The GPS signals are
received
using the GPS receiver 162 and processed by the DSP 158. Typically, GPS
signals
from at least four satellites are processed. Further details of GPS are
omitted for
simplicity.
[0065] The short-range communications subsystem 102 enables communication
between the mobile device 100 and other proximate systems or devices, which
need
not necessarily be similar devices. For example, the short range
communications
subsystem may include an infrared device and associated circuits and
components, or a
BluetoothTM communication module to provide for communication with similarly-
enabled
systems and devices.
[0066] Numerous modifications and variations of the present disclosure are
possible in light of the above teachings. It is therefore to be understood
that within the
scope of the appended claims, the disclosure may be practiced otherwise than
as
specifically described herein.
