U.S. patent application number 13/483510 was filed with the patent office on 2012-11-29 for self configuring and optimisation of cell neighbours in wireless telecommunications networks.
Invention is credited to Harald Kallin, Johan Moe.
Application Number | 20120302235 13/483510 |
Document ID | / |
Family ID | 38462152 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120302235 |
Kind Code |
A1 |
Moe; Johan ; et al. |
November 29, 2012 |
SELF CONFIGURING AND OPTIMISATION OF CELL NEIGHBOURS IN WIRELESS
TELECOMMUNICATIONS NETWORKS
Abstract
The present invention relates to a cellular communications
network and in particular to the problem of identifying cells for
neighbour lists, or handover candidates when the cells are
identified by a limited number of non-unique identities. The
present invention includes a method for a radio base station,
wherein the base station receives reports from one ore more
terminals in neighbour cells quality and non-unique identities. The
match is sought in a neighbour cell list non-unique identity with a
unique cell identity. If the match cannot be made without
ambiguity, the base station orders the terminal to detect the
unique cell identity. If the reason for the ambiguity is the
particular cell is not included in the neighbour cell it is
included when its unique identity has been established. The
uniquely identified cell is used if a handover is decided.
Inventors: |
Moe; Johan; (Mantorp,
SE) ; Kallin; Harald; (Sollentuna, SE) |
Family ID: |
38462152 |
Appl. No.: |
13/483510 |
Filed: |
May 30, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13084884 |
Apr 12, 2011 |
8213941 |
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13483510 |
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11773752 |
Jul 5, 2007 |
7957743 |
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13084884 |
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Current U.S.
Class: |
455/434 |
Current CPC
Class: |
H04W 36/0061 20130101;
H04J 11/0093 20130101; H04W 24/08 20130101; H04W 36/0083 20130101;
H04L 65/4076 20130101; H04W 36/08 20130101; H04W 72/085 20130101;
H04W 16/00 20130101; H04W 88/02 20130101; H04W 36/00835
20180801 |
Class at
Publication: |
455/434 |
International
Class: |
H04W 24/00 20090101
H04W024/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2007 |
EP |
PCT/EP2007/001737 |
Claims
1. A method for a radio base station or for a base station
controller connected to a radio base station and controlling it
wherein the radio base station serves a first cell of a plurality
of cells in a wireless telecommunications system, the method
comprising the steps of: communicating with a mobile terminal in
the first communications cell; receiving from the mobile terminal a
quality measure on a second cell and a non-unique identification of
the second cell; retrieving a neighbour cell list for the first
cell, to match a unique-cell identification with the non-unique
cell identity, and if ambiguity in the match arises instructing the
mobile terminal to determine the unique cell identity of the second
cell; receiving unique cell identifier information relating to the
second communications cell from the mobile terminal; and
associating the non-unique cell identity with the unique cell
identity.
2. A method as claimed in claim 1, wherein ambiguity arises when
the second cell non-unique identity is not included in the
neighbour cell list.
3. A method as claimed in claim 1, wherein ambiguity arises if the
second cell non-unique cell identity is included in the neighbour
cell list with information on suspected ambiguity of
identification.
4. A method as claimed in claim 1, wherein ambiguity arises if two
unique cell identities in the list shares the same non-unique cell
identity.
5. A method as claimed in claim 2, wherein in said associating step
said second cell non-unique and unique cell identities is added to
the neighbour cell list.
6. A method as claimed in claim 3 or 4, wherein in said associating
step said second cell non-unique and unique cell identities is
associated with the communication with the terminal for a
period.
7. A method as claimed in claim 3 or 4, wherein in said associating
step said second cell non-unique and unique cell identities are
associated with the communication with the terminal as long as the
quality measure exceeds a first threshold level
8. A method as claimed in claim 3, wherein information on suspected
ambiguity is added to a non-unique cell identity if one or more
handovers from the first cell to a cell with the non-unique cell
identity has/have been unsuccessful.
9. A method as claimed in claim 1, wherein the quality measure is
at least one of; signal strength measurement, a signal quality
measurement, or timing information.
10. A method as claimed in claim 1, wherein the instructing step is
performed on the further condition of the second cell quality
measure exceeds a second threshold value.
11. A method as claimed in claim 1, wherein the instructing step is
performed on the further condition the second cell is determined to
be a handover candidate.
12. A method as claimed in claim 1, comprising the further steps
of: broadcasting a non-unique identity of the first cell, in a
first information layer intended for carrying information for
supporting the physical connection with the terminals; broadcasting
a unique identity of the first cell on an information layer higher
then the first layer.
13. A radio base station for providing communication in a first
cell with at least one terminal and comprising: a radio
transceiver; a controller including or being connected to a
database that includes a neighbour cell list and including a NCL
utility, the controller being arranged for receiving via the
transceiver reports from the terminal on measured reception quality
on other cells than the first cell, including the other cells
non-unique cell identities, further arranged for matching the
non-unique cell identities with corresponding unique cell
identities by retrieving the neighbour cell list, the NCL utility
arranged for initiating an instruction being sent to the terminal
for identifying and reporting on the unique cell identity of a
non-uniquely identified cell if ambiguity arises in the matching,
the NCL utility further being arranged for associating the
non-unique cell identity and the unique cell identity as reported
by the terminal 14. A method for a mobile terminal, 4, in a
cellular telecommunications network, the method comprising:
communicating, 301, over a first link in a first cell; measuring,
302, a signal quality of a channel broadcasted in a second cell;
detecting, 303, a non-unique cell identity broadcasted in the
second cell: reporting, 304, the measured second cell signal
quality and the identified non-unique identity over the first radio
link; receiving, 305, an instruction over the first radio link to
detect a second cell unique identity; detecting, 306 the unique
cell identity broadcasted in the second cell; reporting, 307, the
unique second cell identity by transmission over the first radio
link.
15. The method of claim 14, wherein the non-unique second cell
identity is detected in a first layer carrying physical
information.
16. The method of claim 14, wherein the unique second cell identity
is detected in a second layer higher than the first layer.
17. A mobile terminal for communicating with a first radio base
station in a first cell and performing measures on the reception
quality from other cells, and comprising: a radio transceiver, a
controller arranged for identifying a non-unique cell identity of
the respective other cells and report to the first radio base
station with the quality measures, and further arranged for
controlling the transceiver to identify a unique cell identity of
one or more of the other cells in response to an instruction
received from the first radio base station.
18. The mobile terminal of claim 17, wherein the controller
includes a CID detector for identifying the non-unique cell
identity.
19. The mobile terminal of claim 17, wherein the controller
includes a UCID detector for identifying the unique cell
identity.
20. A radio base station controller with an interface for
connecting to at least one radio base station and its transceiver
and comprising: a controller including or being connected to a
database that includes a neighbour cell list and including a NCL
utility, the controller being arranged for receiving via the
transceiver reports from at least one terminal on measured
reception quality on other cells than the first cell, including the
other cells non-unique cell identities, further arranged for
matching the non-unique cell identity with a unique cell identity
by retrieving the neighbour cell list, the NCL utility arranged for
initiating an instruction being sent to the terminal for
identifying and reporting on the unique cell identity of a
non-uniquely identified cell if ambiguity arises in the matching,
the NCL utility further being arranged for associating the unique
cell identity as reported by the terminal with the non-unique cell
identity.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 13/084,884, filed Apr. 12, 2011, which is a continuation of
U.S. application Ser. No. 11/773,752, filed on Jul. 5, 2007, which
claims the benefit of International Application No.
PCT/EP2007/01737, filed Feb. 28, 2007, the disclosures of which are
incorporated herein by reference.
[0002] FIELD OF INVENTION
[0003] The present invention relates to self-configuring and
optimisation of cell neighbours in wireless telecommunications
networks.
BACKGROUND OF THE INVENTION
[0004] FIG. 1 of the accompanying drawings illustrates a wireless
telecommunications network, which support communication with
terminals in a number of cells (A, B, C, D) each of which is served
by a radio base station 2. Each communication cell covers a
geographical area, and by combining a number of cells a wide area
can be covered. A mobile terminal 4 is illustrated communicating in
cell A, and is able to move around the system 1.
[0005] A base station 2 contains a number of receivers and
transmitters to give radio coverage for one or more cells. Each
base station 2 is connected to a network "backbone", or core
network infrastructure (not shown), which enables communications
between base stations and other networks. The example system of
FIG. 1 shows one base station per cell.
[0006] An important concept in such a network is the cell and its
neighbours. During a call a mobile terminal 4 typically is moved in
the geography, and when so doing leaves a first cell and enters a
new cell that neighbours the first cell. The cell may be changed
several times and the process of changing the cell that supports a
radio link with the terminal is called handover. A list of the
known neighbours, the so called "neighbour cell set", is important
both for the network 1 and for the mobile terminal 4 to enable
reliable handover between cells. The network 1 can store
information relating to a set of neighbour cells for each cell in
the system. Evaluation of the best cell for supporting a radio link
with the mobile terminal is based upon measurements made by the
terminal on the serving cell and on other cells than the serving
cell. The neighbour cell list is needed for mapping measurements
and handover decisions to a target cell identity and possibly
applying specific parameters or rules for the target cell. It will
be readily appreciated that the cell boundaries are not sharply
defined, but will in practice be somewhat blurred as the range of
the base stations will overlap with one another.
[0007] In existing systems, the mobile terminal, 4, detects and
measures cell operating parameters for neighbouring cells by
measuring on their broadcast channels. One measured operating
parameter is a cell non-unique identifier which typically consists
of a physical layer identifier such as a scramble code which is non
uniquely assigned to the cell. Operating parameters also relates to
the signal quality of the neighbour cell such as signal strength,
signal quality and timing information. When the quality of a
neighbour cell is considered better than the current serving cell,
a handover from the serving cell to the chosen neighbour cell is
executed by the network. The neighbour cell then becomes the
serving cell for the mobile terminal.
[0008] Typically in a WCDMA (wideband code division multiple
access) system, the mobile terminal detects Common Pilot Channel
(CPICH) transmissions from surrounding cells, in order to determine
id (scramble code) and timing information.
[0009] When the mobile reports the neighbour cell signal quality
measurements to the network, the cells' respective identities
become important. Typically, cell identities are reused for more
than one cell. The reuse of identities means that cells may be
confused with one other, since the serving cell may have neighbour
cells sharing the same identity information.
[0010] In the cells are also broadcasted unique cell identities.
The unique cell identity is carried on the network layer. Its main
use is for special purpose terminals, that are used by an operator
of the system for testing and tracing of problems in the network.
The unique cell identity is not repeated as often as the non-unique
cell identity and is more complicated for a terminal to detect.
This is in contrast to the physical layer, that is physical data
needed for supporting the radio link. Since the cells' physical
layer identifiers are non-unique, populating and maintaining the
neighbour cell sets can never be fully automatic. Human efforts are
needed to resolve conflicts where the serving cell has multiple
neighbours using the same non-unique identifier. A further problem
is handover failures owing to the candidate cell has been
incorrectly identified.
SUMMARY OF THE PRESENT INVENTION
[0011] The aim of the present invention is to secure handovers to
be performed to the right cell. It solves the problem with a method
for a radio base station or for a node controlling a radio base
station serving a first cell and comprises the steps of, receiving
from a terminal a non-unique cell identity of a second cell and a
measure on the quality of the second cell, determining if the
second cell can be unambiguously identified by the information in a
neighbour cell list, and if ambiguity in the second cell identity
is determined, ordering the terminal to identifying and reporting
on the unique second cell identity, and associating the non-unique
identity with the unique identity.
[0012] In a first embodiment ambiguity on the second cell identity
is identified if the non-unique cell identity is not included in
the neighbour cell list. The association is then made by including
the second cell non-unique cell identity and the unique cell
identity in the neighbour cell list. In a second embodiment
ambiguity on the second cell identity arises if two unique cell
identities in the neighbour cell list have the same non-unique
identity. The association with the unique cell identity with the
non-unique cell identity is then made for the specific radio link
with the terminal for a period. The period is typically started
with the signal strength of the second cell exceeded a predefined
threshold value, and ending when a handover is performed or the
second cell signal strength decreases under a second threshold
value.
[0013] The invention also relates to a radio base stations or a
node controlling radio base stations and that is adapted for
performing the method.
[0014] The invention also includes a method for mobile stations
that measures the signal quality on broadcast channels in other
cells than the first cell, detects the non unique cell identity on
broadcast channels with a quality exceeding a threshold value,
transmitting information on the signal quality and second cell
non-unique identity to the serving cell and upon receiving a
command, detecting the unique cell identity on a broadcast channel
and transmitting the unique cell identity.
[0015] The invention further relates to a mobile station adapted
for performing the method.
[0016] An advantage of the present invention is that creation and
or updating of a neighbour cell list can be made automatically by
the system based on the measurements and cell identity information
received from the terminals. Thereby, it is not necessary for
humans to plan and maintain the neighbour cell lists.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 illustrates a cellular wireless telecommunications
network;
[0018] FIG. 2 illustrate steps of method for a base station or a
base station controller.
[0019] FIG. 3 illustrate steps of a method for a terminal.
[0020] FIG. 4a is a block diagram of a mobile terminal.
[0021] FIG. 4a is a block diagram of a base station.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The basic problem of the present invention is to make a
positive identification of a neighbouring cell that is ambiguously
detected by a mobile terminal. The ambiguity may arise when a cell,
not previously detected, is reported by a mobile terminal, or when
two or more cells share the same non-unique cell identity and the
two cells. An ambiguity will then arise on what cell that has been
measured.
[0023] The problem exists in several systems, for example GSM,
WCDMA and eUTRAN. In GSM and WCDMA a list of neighbour cells is
created for each cell in the system by a human or at least
controlled by a human. In so doing any collisions in the non-unique
cell identities of the neighbours should be detected and possibly
solved by reallocating the non-unique cell identities. It is
cumbersome to establish and update the NCL (neighbour cell list)
and the allocations of non-unique cell identities, especially when
the capacity of a network is increased by the addition of further
cells.
[0024] For WCDMA and eUTRAN it is desired that the NCL can, if not
be completely created automatically, at least be updated
automatically by the system based on measurements made by terminals
on cells other than the cell serving the terminal. For that reason
the present inventions is in particular important for the WCDMA and
eUTRA, however, it may well be implemented also in other systems
such as the GSM.
[0025] The inventions will primarily be implemented in a network
node that handles the NCL and decides on handovers. In the eUTRAN
this is the task of the eNodeB which is a base station, in the GSM
it is the BSC (Base Station Controller) and in the WCDMA it is the
RNC (Radio Network Controller) that handles the NCL. Both the BSC
and the RNC have the functions of controlling the base stations and
their operation on the various cells of the networks, and the term
base station controller in this application refers to a node having
the functions of the BSC or the RNC.
[0026] FIG. 2 is a flow chart of the steps performed by a a radio
base station, 2, or a base station controller. For facilitating the
description only the base station, 2, is mentioned when describing
the method. It should be understood that the steps are
alternatively carried out by the base station controller. In the
first step 201 a communications link with a terminal, 4, in a first
cell is supported. The base station receives; see step 202, a
report from the terminal on a quality measure and a non-unique cell
identity of a second cell. Next, 203, the base station retrieves
the NCL to match the non-unique cell identity with a unique cell
identity. If, see step 204, the match is made without any ambiguity
the method is ended with respect to the second cell. If however
ambiguity arises in the match, the base station instructs, 205, the
terminal to detect the unique cell identity of the second cell. The
base station receives the unique cell identity, 206, and in a last
step, 207, the non-unique cell identity is associated with the
unique cell identity within the NCL.
[0027] There are several reasons why the ambiguity may arise in the
match between non-unique cell identity and the unique cell
identity. The first, and basic reason is the second cell is not
included in the NCL. Another reason is the NCL includes an
indicator of suspected ambiguity. The indicator may have been added
to the NCL prior to the method is being performed. The reason may
be handovers to the identified cell have failed. The failure may be
detected as terminals have re-established contact with the first
cell as serving cell during handover processes, or the target cell
has not sent notification to the first cell as serving cell. A
further reason for ambiguity is two or more unique cell identities
share the same non-unique cell identity.
[0028] If the reason for the ambiguity is that the second cell with
its unique and non unique cell identities is not included in the
NCL they are added to it in the last associating step, 207.
[0029] The base station frequently receives, 202, reports from the
terminal on measures made on other cells, and then not only the
second cell. When the base station has received, 206, the second
cell unique identity as detected by the terminal it shall not
instruct the terminal to detect the second cell unique identity
when again receiving, 202, a quality measure from the terminal, not
even if the ambiguity in the NCL is maintained. Therefore, the
associating step, 207, shall associate the unique cell identity
with the non-unique cell identity for this particular terminal for
a specific period or as long as the signal quality of the second
cell exceeds a predefined threshold. The association with the
particular terminal is not made in the NCL, instead a temporary NCL
is used.
[0030] As long as the second cell unique cell identity is
associated with the terminal, if handover to the second cell is
decided it will be directed via the associated second cell unique
identity. Thereby the second cell will be instructed to prepare a
handover of the terminal, before the terminal itself is instructed
to make a handover to the second cell.
[0031] In addition to the requirement of ambiguity in the match of
unique cell identity to the non-unique cell identity, the further
requirement of the second cell quality measure exceeding a
threshold value can be added before the terminal is instructed to
detect the second cell unique identity. The reason for adding the
further requirement is to avoid expense of the terminal performing
the detection. The unique cell identity is transmitted from base
stations at a much less frequent interval than the physical layer
identity. In order to receive and decode this information, the
mobile terminal 4 may have to shortly interrupt its communication
with the serving cell.
[0032] Moreover, some filtering of the measurement data may be
needed before the second cell is added to the NCL in the
associating step 207. For example the second cell is not included
until it has been reported by two or more mobile terminals. Thereby
avoiding adding a distant cell that was detected under exceptional
propagation conditions, for example from a mobile terminal 4
located in an aircraft.
[0033] Additionally in step 207, cell lookup maps the unique cell
identity (UCID) to the address of the realising node of that cell.
For example, in LTE, this can be an ordinary DNS, mapping the cell
identity to an IP address. The IP address in turn points to the RBS
realising the cell.
[0034] FIG. 3 is a flowchart of the steps to be performed by a
mobile terminal. In a first step 301, the terminal is in
communication with the first cell over a first radio link. In the
next step, 302, the terminal measures the quality of a broadcast
channel transmitted in a second cell, and detects, 303, the second
cell non-unique identity as sent on layer 1 communication. In a
fourth step, 304, the terminal transmits the second cell non-unique
identity, and quality measure over the first link. The quality
measure and the non-unique identity are tied together in the
transmission. In a following step, 305, the terminal receives an
instruction over the first link to detect the second cell unique
identity. Next, 306, the terminal detects the second cell unique
identity as broadcasted on network layer. In the last step, 307,
the terminal transmits the second cell unique identity over the
first link.
[0035] The terminal 4 scans the spectrum to find broadcast channels
of potential neighbour cells. The ability to detect and measure a
broadcast channel depends on the sensitivity of the hardware in the
terminal transceiver and of the broadcast channel power relative to
the interference level. A further prerequisite for detecting the
second cell identity of the potential neighbour cell in step 303
may be added, and that be the broadcast channel reception quality
as detected in step 302, exceeds a threshold value. If the
non-unique cell identity is not detected, the second cell is of
course not informed to the network, in step 304.
[0036] FIG. 4a is a block diagram of parts of a mobile terminal 4
that are essential for the present invention. The mobile terminal 4
comprises a controller 42, a man machine interface (MMI) 44, a
radio transceiver 46, and an antenna 48. The controller 42 of the
mobile terminal 4 serves to control communications with the base
station 2 via the transceiver 46 and antenna 48, over the air
interface 6. This means the controller 42 have the function of
receiving control messages from the base station, and control the
operation of the mobile terminal in accordance with the control
messages. Data detected by the transceiver passes through
controller 42. The controller reads control information on the
physical layer. With respect to measures on other cells than the
serving cell the controller 42 receives the measures on the
reception quality and identifies the non-unique cell identity. The
controller further collects measures and the associated non-unique
cell identities and reports to the radio base stations regularly.
The controller is equipped with a CID (cell identity) detector 47
for identifying the non-unique cell identity in the physical layer
information. The terminal blocks and functioning so far described
are the same as for prior art terminals 4. However, the functioning
of the controller is adapted for the present invention. The
controller has a request receiver 49, arranged for detecting a
control message from the serving base station on identifying the
unique cell identity of a cell of a non-unique cell identity. When
such a request has been received, the controller 42, controls the
transceiver 46 to detect data on the second cell broadcast channel,
until the unique cell identity has been identified. The controller
42 is equipped with a UCID detector that reads the information on
the network layer, as received form the transceiver. The controller
42 controls the transceiver to continue detecting data on the
broadcast channel until the UCID detector has found the unique cell
identity. Owing to the unique cell identity is repeated with long
intervals, the identification of the unique cell identity requires
the transceiver to detect the broadcast channel longer time than if
just then non-unique identity need be detected.
[0037] The CID detector 47, the UCID detector 48, and the request
receiver 49 are preferably implemented as SW modules, however, they
may alternatively be implemented in hardware or in a combination of
the two.
[0038] Interactions with the user of the device take place using
the man machine interface 44, which can include a key pad,
microphone, loudspeaker and display device, for example.
[0039] FIG. 4b is a block diagram of a base station 2 which
communicate via an air interface 6. Only blocks essential for the
present invention are disclosed. The base station 2 includes an
input/output (I/O) interface 24, a radio transceiver 26 an antenna
28 and a controller 22. The controller communicates with mobile
terminals via the transceiver 26 and antenna 28 over the air
interface 6. The controller 22 also communicates with the rest of
the telecommunications network via the I/O interface 24. For this
invention the controller also includes NCL utility, 21, a storage
device, 27, a temporary NCL, 23, and a NCL, 25. The controller
retrieves the NCL for identifying the unique cell identifiers for
the non-unique cell identifiers reported by the terminals. These
aspects of the base station are designed to operate in accordance
with usual practice. The NCL unit monitors if the match between
non-unique and unique cell identity can be made without ambiguity.
If ambiguity exist the NCL unity initiates an instruction is sent
to the terminal for it to report of the unique cell identity of the
non-uniquely identified cell. When the unique cell identity is
reported by the terminal, the NCL utility 22 controls the unique
and the non-unique cell identity are listed and associated with the
terminal identity in the temporary NCL. A further condition for
listing in the temporary NCL is the reported reception quality is
above a first threshold level. The NCL utility 22 also controls the
non-relevant association to be deleted. Typically this is made when
the signal strength of a cell on the temporary NCL has decreased
under a second threshold level. Alternatively the data base 27 with
NCL and temporary NCL are located outside the controller and
connected to it.
[0040] Typically the controller will also decide on handovers from
the serving base station to a target base station serving the
second cell, or which of the other cells that temporary will
function as second cell.
[0041] In an alternative to the base station described with
reference to FIG. 4b, the controller 22 is located in a radio
network controller. The radio network controller with internal
controller is then connected to at least one radio base station
transceiver. The functioning of the internal controller 22 will
then be the same as described in connection to the radio base
station.
[0042] However, base stations 2 and mobile terminals 4 which
operate in accordance with the present invention are adapted to
carry out the method of the invention as described below with
reference to FIGS. 3 to 6. It will be appreciated that the various
functional units can be provided by the controller 42, 22, or by
other specific units in the devices, or network 1.
[0043] Making use of unique cell identifiers (UCID) means that
there is unambiguous information relating to the identity of the
neighbour cells, and so confusion regarding those neighbouring
cells is removed. Using the fast and low-resource demanding
non-unique cell identity for most of the measurements, facilitates
efficient resource usage within mobile terminals 4 and rapid
handover to the neighbour cells. The mobile terminal 4 is only
requested to retrieve the more cumbersome unique cell identifier
when a new neighbour is detected, or when an audit of the relation
between the non-unique and unique cell identity seems
appropriate.
[0044] All cell relations can be continuously evaluated. Inputs to
that evaluation are mobile terminal reports and events, network
events and operator input. The result of the evaluation is that the
cell or cell relations will retain different properties. This can
also be seen as the cell relation being in different states.
[0045] The major advantage of embodiments of the present invention
is that it removes the need for manual involvement within the
process of maintaining neighbour sets. The operator can decide to
fully neglect the concept of neighbours and let the system take
care of the neighbour cell definitions.
* * * * *