U.S. patent application number 11/896047 was filed with the patent office on 2007-12-27 for cellular network acquisition method and apparatus.
This patent application is currently assigned to NEC CORPORATION. Invention is credited to Darioush Downer, Frederic Gabin, Nigel Legg, Richard Ormson, Osamu Yamashita.
Application Number | 20070298790 11/896047 |
Document ID | / |
Family ID | 9948118 |
Filed Date | 2007-12-27 |
United States Patent
Application |
20070298790 |
Kind Code |
A1 |
Ormson; Richard ; et
al. |
December 27, 2007 |
Cellular network acquisition method and apparatus
Abstract
A method of network acquisition for a cellular radio
communications device arranged for operation in accordance with a
plurality of radio technologies and comprising searching to
identify a suitable cell on one radio technology. Subsequent to
identifying a suitable cell on the one radio technology, cells on
another of the plurality of radio technologies are also monitored
in order to identify if one of the monitored cells is more suitable
than the cell identified on the one radio technology. Subsequent to
the monitoring, the cell identified from all of the radio
technologies searched as the most suitable is selected and camping
for the first time occurs onto that cell.
Inventors: |
Ormson; Richard; (Berkshire,
GB) ; Gabin; Frederic; (Bangor, FR) ; Downer;
Darioush; (Berkshire, GB) ; Legg; Nigel;
(Berkshire, GB) ; Yamashita; Osamu; (Berkshire,
GB) |
Correspondence
Address: |
MCGINN INTELLECTUAL PROPERTY LAW GROUP, PLLC
8321 OLD COURTHOUSE ROAD
SUITE 200
VIENNA
VA
22182-3817
US
|
Assignee: |
NEC CORPORATION
Tokyo
JP
|
Family ID: |
9948118 |
Appl. No.: |
11/896047 |
Filed: |
August 29, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10714892 |
Nov 18, 2003 |
|
|
|
11896047 |
Aug 29, 2007 |
|
|
|
Current U.S.
Class: |
455/434 |
Current CPC
Class: |
H04W 88/06 20130101;
H04W 48/18 20130101; Y02D 30/70 20200801; Y02D 70/1222 20180101;
Y02D 70/1242 20180101 |
Class at
Publication: |
455/434 |
International
Class: |
H04Q 7/20 20060101
H04Q007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2002 |
GB |
0226978.5 |
Claims
1. A method of network acquisition, comprising: identifying a
suitable cell on a first radio technology (RAT); at least one other
RAT for possible neighboring cells of said cell already identified
as a suitable cell in said first RAT; determining a most suitable
cell from among said suitable cell on said first RAT and any of
said neighboring cells monitored on said at least one other RAT;
and camping onto said most suitable cell as an initial camping
during a power up sequence.
2. A device that operates with a plurality of radio technologies
(RATs), said device comprising: a detection module for monitoring
cells on more than one of said plurality of RATs and for
identifying which cell in said plurality of RATs is most suitable
for camping; and a controller for camping on said cell identified
as most suitable, to be an initial camping during a power up
sequence of said device, wherein said controller first identifies a
suitable cell in a first RAT during said power up sequence, then
monitors cells in at least one other RATs that are neighboring
cells of said suitable cell without camping on said suitable cell
in said first RAT, and then identifies said most suitable cell
based on said monitoring of said neighboring cells.
Description
[0001] The present application is a continuation application of
U.S. patent application Ser. No. 10/714,892, filed on Nov. 18,
2003.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method and apparatus for
use in network acquisition for cellular communications devices.
[0004] 2. Description of the Related Art
[0005] Cellular communications devices such as cell phones, have
become increasingly popular and widely adopted and in many
instances have become the prime means of communication both for
business and domestic requirements.
[0006] As such usage becomes more widespread, potentially
disadvantageous and limiting features of such devices become more
apparent. For example, when a cell phone is first turned on, an
acquisition procedure needs to be conducted so that the cell phone
can acquire the appropriate communications method and subsequently
take part in a communications exchange over that network. The
period between turning the cell phone on and actually acquiring the
network does not generally go unnoticed by the user and comprises
dead time as far as the user is concerned since no other operations
over and above network acquisition are conducted during that
period. The longer the time period required to acquire the network,
the more likely this period is to be noticed by the user and so as
to lead to potential irritation.
[0007] Also, network acquisition procedures require the cell phone
handset to expend a significant amount of power relative to power
requirements arising merely for communication procedures.
[0008] Indeed, in view of the different mobile communication modes
that have arisen, and the subsequent requirement for cell phone
handsets to offer dual mode, or indeed multimode, operability, it
will become increasingly necessary for each handset to search on
more than one mode. Thus potential delays in network acquisition,
and related user irritation, could become more frequently
experienced. As explained further below network acquisition
requires a search through a set of frequencies--generally defined
by a frequency band in an attempt to identify the most suitable
cell of a network. With dual mode operation, there will be multiple
sets of frequencies to search through in order not only to find the
most suitable cell, but also the most suitable network given the at
least dual mode operability of the handset
SUMMARY OF THE INVENTION
[0009] The present invention seeks to provide for a network
acquisition method and apparatus which exhibits advantages over
known such methods and apparatus.
[0010] According to one aspect of the present invention, there is
provided a method of network acquisition for a cellular radio
communications device arranged for operation in accordance with a
plurality of radio technologies and comprising searching to
identify a suitable cell on one radio technology and, subsequent to
identifying a suitable cell on the said one radio technology,
comprising the steps of also monitoring cells on another of the
plurality of radio technologies in order to identify if one of the
said monitored cells is more suitable than the cell identified on
the said one radio technology, and subsequent to said monitoring,
selecting and camping for the first time on the cell identified
from all of the radio technologies searched as the most
suitable.
[0011] The invention is particularly advantageous in improving the
initial search procedure when turning on a cellular radio
communications device so as to advantageously reduce dead time
experienced by the user and also to reduce handset energy
consumption. In particular, the arrangement can save the handset
from transmitting unnecessary signalling information and which
procedures exhibit a high power requirement. The network is also
saved from dealing with unnecessary signalling and processor
loadings.
[0012] Advantageously, subsequent to identifying a suitable cell on
the said one radio technology, the method can be arranged to
monitor neighbouring cells on all the plurality of radio
technologies of interest.
[0013] Yet further, and subsequent to the identification of a
suitable cell on the said one radio technology, the method can be
arranged to obtain the BA list provided for that identified cell
but for the other of the available radio technologies.
[0014] In such a manner, the method is arranged to monitor cells on
both radio technologies.
[0015] Preferably, when searching to identify a suitable cell, the
cells are ranked in accordance with signal strength, or a
derivative of signal strength, of signals received there from.
[0016] According to another aspect of the present invention there
is provided a cellular radio communications device arranged for
operation in accordance with a plurality of radio technologies and
including means for searching to identify a suitable cell on one
radio technology and means for monitoring cells on another of the
plurality of radio technologies, subsequent to the identification
of a suitable cell on the said one radio technology, so as to
identify if one of the said monitored cells might prove more
suitable than the said identified cell, and further including means
for, subsequent to the said monitoring, selecting and camping on
the cell identified as the most suitable.
[0017] Advantageously, the cellular radio communications device is
arranged to operate in accordance with method steps as defined
above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The invention is described further hereinafter, by way of
example only, with reference to the accompanying drawings in
which:
[0019] FIG. 1 is a flow chart illustrating network acquisition in
relation to a plurality of radio technologies as currently known;
and
[0020] FIG. 2 is a flow diagram illustrating a method of network
acquisition for use in relation to a plurality of radio
technologies and according to an embodiment of the present
invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION
[0021] As will be appreciated, under the 3GPP specifications a
handset is required to search one entire radio access technology
(RAT) at a time. The relative priority of RATS is set within the
handset and so in a dual mode GSM/UMTS handset an initial search of
GSM or UMTS will be undertaken and the process will only look at
the second RAT during initial selection if no suitable cells are
found on the first RAT.
[0022] However, it may be that a cell on the second RAT is more
suitable than a cell that has been located on the first RAT. Under
the current scheme of operation, this will be detected after the
handset has camped onto the cell found on the first RAT, read the
neighbour cell lists, and monitored the cells of the second RAT. A
reselection will then be performed. As this is an inter-RAT
reselection, it is not a simple procedure and involves significant
signalling traffic. Disadvantageously, this takes time and consumes
energy.
[0023] Turning now to FIG. 1, the known method, for a dual mode
phone, starts by searching the first radio technology RAT at step
10 in order to determine, at step 12, whether a suitable cell has
been located.
[0024] If, at step 12, it is found that no suitable cell is
located, the method proceeds to step 14 where the cells of the
second RAT are searched to identify, at step 16, whether a suitable
cell has been found.
[0025] If, at step 16 it is found that no suitable cell is
identified on the second RAT, then the method returns to original
step 10 via a holding step 18.
[0026] However, if in either of steps 12 or 16 it is found that a
suitable cell does exist on one of the RATs, then the decision is
taken at step 20 to camp on that cell for network acquisition
purposes.
[0027] However, in accordance with the current art, in order to
ensure that a more suitable cell does not exist elsewhere, once
having identified an initially suitable cell, the method proceeds
by steps 20, 24 by reading the BA (neighbour cell) list provided on
that cell for both RATS, and also monitoring neighbouring cells on
both RATS. If, after step 24, it is found at step 26 that a more
suitable cell does not in fact exist than the one initially
identified and camped upon at step 20, then the method proceeds to
step 28 into its idle mode of operation.
[0028] However, if, at 26, it is determined that a more suitable
cell than that camped upon at step 20 is in fact found, then the
method proceeds to step 30 which seeks to determine whether or not
this seemingly more suitable cell is found on the different RAT
from which the cell camped upon at step 20 is found.
[0029] If this is not the case, then the cell of that RAT is simply
reselected at step 32 and the method then proceeds into its idle
mode at step 28.
[0030] However, if it is fact found at step 30 that the more
suitable cell is located on the other RAT, then, at step 34, it is
necessary to decamp from the first RAT and subsequently camp on the
cell associated with the other of the two RATs.
[0031] Such processing can prove to be disadvantageous both as
regards time delays and, in particular, power consumption. Step 20
and step 34 use relatively large amounts of power as they are
procedures requiring the handset to transmit significant levels of
signalling to the network.
[0032] Turning now to FIG. 2, however, there is an illustrated
example of an embodiment of the present invention which offers
advantages over that described in relation to FIG. 1.
[0033] It is therefore proposed that, before camping on to a cell
identified on one RAT, the BA list provided on that cell for the
alternate RAT should be read, and the cells monitored to see if any
are preferable. This will lead to the initial search procedure
taking a fraction of a second longer (unless combined with parallel
search techniques which we describe in other applications).
However, the mechanism potentially saves the handset transmitting
unnecessary signalling and expending significant energy. Of course
this also saves the network from dealing with unnecessary
signalling--while the network is not particularly interested in the
energy saving this provides, the mechanism also reduces the network
signalling and processor loadings, which are useful effects.
[0034] Turning to FIG. 2, there is illustrated a somewhat similar
initial procedure to that illustrated in FIG. 1, in which, at step
36, a search of the first RAT is conducted to identify, at step 38,
whether a suitable cell has been located. If the suitable cell has
not been located, the method proceeds to step 40 and a search of
the second RAT to identify, at step 42, whether a suitable cell has
been located on that second RAT. If no suitable cell is determined
from the second RAT either, the process returns to initial step 36
via a holding step 44.
[0035] However, if, at step 38, a suitable cell is identified on
the initial RAT searched at step 38, or indeed on the second RAT
searched at step 42, the method proceeds to step 46 at which BA
lists provided on that cell for the alternate RAT are read, and the
cells monitored to identify if any likely more suitable cell to
that identified at step 38 exists.
[0036] Importantly, it is noted that in accordance with the present
invention at this stage no camping onto a cell has yet
occurred.
[0037] Subsequent to steps 46,48 it is determined whether or not a
more suitable cell than that identified at step 38 has been
located.
[0038] If not, the method proceeds to step 52 at which the handset
camps onto the original cell found at either of steps 38 and
42.
[0039] However, if the determination at step 50 indicates that a
likely more suitable cell has in fact been located, then steps are
simply taken at step 54 to camp onto the likely more suitable cell,
Subsequent to the camping onto the appropriate cell at either of
steps 52, 54, the method then proceeds into the idle mode 56 for
the handset.
[0040] Thus, it will be appreciated from FIG. 2 that, whichever RAT
eventually provides for the most suitable cell, only one camping
step, and no subsequent de-camping step, is required.
[0041] This is best illustrated by a comparison of stage A in FIG.
1, with stage B in FIG. 2. stage B requiring far less power
expenditure than stage A.
[0042] This mechanism is a dual mode search, and operates in a way
compatible with the 3GPP specifications. However the mechanism is
not limited to those technologies described in the 3GPP
specifications; it is applicable to any multi RAT system where
information on alternate RAT cells is provided in RAT broadcast
information.
* * * * *