U.S. patent application number 13/440880 was filed with the patent office on 2012-10-11 for multimode base station.
Invention is credited to Fiona Clare Angharad Somerville, Nicholas William Whinnett.
Application Number | 20120258713 13/440880 |
Document ID | / |
Family ID | 44071998 |
Filed Date | 2012-10-11 |
United States Patent
Application |
20120258713 |
Kind Code |
A1 |
Whinnett; Nicholas William ;
et al. |
October 11, 2012 |
Multimode Base Station
Abstract
A method of controlling admission of a user equipment to a cell
of a multi-mode base station, being a base station arranged to
operate as a plurality of cells, the plurality of cells comprising
at least a first cell and a second cell, and the method comprising:
determining information relating to the first cell, and controlling
admission of a user equipment to the second cell in dependence on
the information relating to the first cell.
Inventors: |
Whinnett; Nicholas William;
(Marlborough, GB) ; Somerville; Fiona Clare Angharad;
(Bristol, GB) |
Family ID: |
44071998 |
Appl. No.: |
13/440880 |
Filed: |
April 5, 2012 |
Current U.S.
Class: |
455/435.1 |
Current CPC
Class: |
H04W 48/20 20130101;
H04W 72/085 20130101; H04W 72/0486 20130101; H04W 36/245 20130101;
H04W 84/045 20130101; H04W 88/06 20130101 |
Class at
Publication: |
455/435.1 |
International
Class: |
H04W 8/02 20090101
H04W008/02; H04W 88/00 20090101 H04W088/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 5, 2011 |
GB |
GB 1105769.2 |
Claims
1. A method of controlling admission of a user equipment to a cell
of a multi-mode base station, being a base station arranged to
operate as a plurality of cells, the plurality of cells comprising
at least a first cell and a second cell, and the method comprising:
determining information relating to the first cell, and controlling
admission of a user equipment to the second cell in dependence on
the information relating to the first cell.
2. The method of claim 1, wherein: the determination of the
information comprises monitoring statistics of past behavior of the
user equipment when connected to the first cell, and the
controlling admission is dependent on the statistics of the past
behavior of the user equipment in the first cell.
3. The method of claim 2, comprising monitoring statistics relating
to past behavior of the user equipment when connected to the second
cell, and controlling admission of the user equipment to the second
cell in dependence on the statistics relating to past behavior of
the user equipment in both the first cell and the second cell.
4. The method of claim 2, further comprising receiving a request
from the user equipment for admission to the first cell and, in
response to the request for admission to the first cell, admitting
the user equipment to the second cell based on the statistics
relating to past behavior of the user equipment in the first
cell.
5. The method of claim 3, wherein the admission of the user
equipment to the second cell in response to the request for
admission to the first cell is based on the statistics relating to
past behavior of the user equipment in both the first cell and the
second cell.
6. The method of claim 4, wherein the user equipment is admitted to
the second cell based on the statistics relating to past behavior
before the user equipment indicates quality of service requirements
to the base station.
7. The method of claim 2, further comprising receiving a request
from the user equipment for access to the second cell, and in
response to the request admitting the user equipment to the second
cell based on the statistics relating to past behavior of the user
equipment in the first cell.
8. The method of claim 3, wherein the admission of the user
equipment to the second cell is based on the statistics relating to
past behavior of the user equipment in both the first cell and the
second cell.
9. The method of claim 7, wherein the user equipment is admitted to
the first cell based on the statistics relating to past behavior
before the user equipment indicates quality of service requirements
to the base station.
10. The method of claim 2, wherein the statistics relating to past
behavior of the user equipment comprise at least one of a downlink
throughput requested by the user equipment from the respective
cell, and an uplink throughput requested by the user equipment from
the respective cell.
11. The method of claim 2, wherein the statistics relating to past
behavior of the user equipment comprise at least one of a downlink
throughput used by the user equipment in the respective cell, and
an uplink throughput used by the user equipment in the respective
cell.
12. The method of claim 2, wherein the statistics relating to past
behavior of the user equipment comprise at least one of a downlink
latency requested by the user equipment from the respective cell,
and an uplink latency requested by the user equipment from the
respective cell.
13. The method of claim 2, wherein the statistics represent a
predetermined period, and the method further comprises determining
an average of the statistics representing the period, and the
control of admission is based on the average.
14. The method of claim 13, further comprising determining a
variation of the average of the statistics representing the period,
and the control of admission is based on the variation of the
average.
15. The method of claim 1, wherein: the determination of the
information comprises determining a prediction of performance of
the first cell, and the control of admission is dependent on the
prediction of performance in the first cell.
16. The method of claim 15, further comprising determining a
prediction of performance of the second cell and the control of
admission is dependent on the prediction of performance for both
the first cell and the second cell.
17. The method of claim 15, further comprising receiving a request
from the user equipment for admission to the first cell and, in
response to the request for admission to the first cell, admitting
the user equipment to the second cell based on the prediction of
performance of the first cell.
18. The method of claim 17, wherein the admission of the user
equipment to the second cell in response to the request for
admission to the first cell is based on the prediction of
performance of both the first cell and the second cell.
19. A multi-mode base station arranged to operate as a plurality of
cells, the plurality of cells comprising at least a first cell and
a second cell, and the base station comprising: a radio resource
manager for controlling admission of a user equipment to the cells,
the radio resource manager being configured to: determine
information relating to the first cell, and control admission of a
user equipment to the second cell based on the information relating
to the first cell.
20. A computer program product for controlling access to a cell of
a multi-mode base station, the a base station arranged to operate
as a plurality of cells, the plurality of cells comprising at least
a first cell and a second cell, and the computer program product
being embodied on a non-transient computer-readable medium and
configured such that when executed on a processor of the base
station it determines information relating to the first cell, and
controls admission of a user equipment to the second cell based on
the information relating to the first cell.
Description
1. PRIORITY CLAIM
[0001] This application claims priority to and the benefit of Great
Britain Application No. 1105769.2 filed on Apr. 5, 2011.
2. FIELD OF THE INVENTION
[0002] The present invention relates to controlling admission of
user equipment to a cell of a multimode base station (such as
multimode picocell, femtocell or the like) which is arranged to
operate as two or more logical cells.
3. RELATED ART
[0003] As will be familiar to a person skilled in the art, a base
station is the unit which provides a user equipment such as a
mobile phone or computer with access to a wireless cellular network
such as a network operating according to both 3G and 4G standards,
the base station being the first stage up from the user equipment
in the cellular hierarchy, i.e. the unit with which the user
equipment immediately communicates via a wireless connection
(without an intermediary station). According to 3GPP terminology, a
base station is sometimes referred to as a "node B", but the more
generic term "base station" will be maintained herein for
convenience.
[0004] A femtocell is a type of cellular base station designed to
operate over a relatively short range compared to a conventional
base station. Short-range dedicated base stations such as
femtocells have become more viable in recent years due to reduction
in the cost and size of the electronics required to implement a
cellular base station. The idea is to provide a dedicated base
station to cover a relatively small geographical area which is
expected to experience a high density of users and/or regular
usage. For example femtocells are typically intended to be deployed
in a small office, shop, cafe or even the home. Other types of
short range base stations include picocells or microcells,
typically covering an intermediately sized area; although the scope
of femtocells is increasing as they are encroaching on what have
been traditionally called picocells and microcells, supporting
large offices, shopping malls and outdoor deployments. The scope of
femtocells is increasing due to increased functionality over
picocells and microcells. In some wireless standards, femtocells
combine the functionality of several wireless network elements, for
example in UMTS a femtocell combines the functionality of a base
station and radio network controller (RNC). Also, it is typical for
a femtocell to be installed by the end user, not the network
operator, and extra functionality is required to support this, such
as the ability to locate (sniff) neighboring base stations. This is
in contrast to picocells and microcells that are installed by a
network operator and only provide base station functionality.
[0005] Base-stations (BS), including femtocells, contain a radio
resource management (RRM) entity which includes admission control
mechanisms to decide whether a new connection request from a user
equipment (UE) should be admitted. This RRM entity may refuse the
UE access to the BS due to it being congested and unable to support
more users. This congestion can be on the air-interface, but could
also be related to hardware processing resources, or back-haul
congestion. When a base-station experiences congestion it has the
following options: [0006] If the UE is very high priority, for
example, an emergency call, it must accept this UE and release or
downgrade an alternative UE. [0007] The base-station can direct the
UE to an alternative base-station for service, where this
base-station could be at a different frequency sub-band or a
different radio access technology (RAT). [0008] The base-station
can offer to service the UE with a lower quality of service (QOS)
than it requested. [0009] The base-station can refuse service to
the UE and not provide any alternatives.
[0010] A dual-mode femtocell is a base-station operating as two
cells. These cells could be operating as different RATs, or the
same RATs but in different sub-bands. Each cell operates an
independent RRM admission control mechanism.
SUMMARY
[0011] If both the cells operate an independent RRM admission
control mechanism then this can lead to inefficient use of
base-station resources--a UE could be admitted to the least optimum
cell for its QOS, or one cell could be fully loaded while the other
is only lightly loaded. Improvements could be achieved by
performing joint admission control for a dual-mode femtocell. These
improvements can be related to the throughput and QOS achieved by
the admitted UE, other UE in the same cell, or UEs in neighboring
cells.
[0012] Therefore according to one aspect of the present invention,
there is provided a method of controlling admission of a user
equipment to a cell of a multi-mode base station, being a base
station arranged to operate as a plurality of cells, the plurality
of cells comprising at least a first cell and a second cell, and
the method comprising: determining information relating to the
first cell, and controlling admission of a user equipment to the
second cell in dependence on the information relating to the first
cell.
[0013] In embodiments the determination of the information may
comprise monitoring statistics of past behavior of the user
equipment when connected to the first cell, and the control of
admission may be dependent on the statistics of the past behavior
of the user equipment in the first cell.
[0014] The method may comprise monitoring statistics relating to
past behavior of the user equipment when connected to the second
cell, and controlling admission of the user equipment to the second
cell in dependence on the statistics relating to past behavior of
the user equipment in both the first cell and the second cell.
[0015] The method may comprise receiving a request from the user
equipment for admission to the first cell and, in response to the
request for admission to the first cell, admitting the user
equipment to the second cell based on the statistics relating to
past behavior of the user equipment in the first cell.
[0016] The admission of the user equipment to the second cell in
response to the request for admission to the first cell may be
based on the statistics relating to past behavior of the user
equipment in both the first cell and the second cell.
[0017] The user equipment may be admitted to the second cell based
on the statistics relating to past behavior before the user
equipment indicates quality of service requirements to the base
station.
[0018] The method may comprise receiving a request from the user
equipment for access to the second cell, and in response to the
request admitting the user equipment to the second cell based on
the statistics relating to past behavior of the user equipment in
the first cell.
[0019] The admission of the user equipment to the second cell may
be based on the statistics relating to past behavior of the user
equipment in both the first cell and the second cell.
[0020] The user equipment may be admitted to the first cell based
on the statistics relating to past behavior before the user
equipment indicates quality of service requirements to the base
station.
[0021] The statistics relating to past behavior of the user
equipment may comprise at least one of: a downlink throughput
requested by the user equipment from the respective cell, and an
uplink throughput requested by the user equipment from the
respective cell.
[0022] The statistics relating to past behavior of the user
equipment may comprise at least one of a downlink throughput used
by the user equipment in the respective cell, and an uplink
throughput used by the user equipment in the respective cell.
[0023] The statistics relating to past behavior of the user
equipment may comprise at least one of a downlink latency requested
by the user equipment from the respective cell, and an uplink
latency requested by the user equipment from the respective
cell.
[0024] The statistics may represent a predetermined period, the
method may comprise determining an average of the statistics
representing the period, and the control of admission may be based
on the average.
[0025] The method may comprise determining a variation of the
average of the statistics representing the period, and the control
of admission may be based on the variation of the average. The
statistics may represent a predetermined period of at least one
day. The statistics may represent a predetermined period of at
least one week. In further embodiments, the determination of the
information may comprise determining a prediction of performance of
the first cell, and the control of admission may be dependent on
the prediction of performance in the first cell.
[0026] The method may comprise determining a prediction of
performance of the second cell, and the control of admission may be
dependent on the prediction of performance for both the first cell
and the second cell.
[0027] The method may comprise receiving a request from the user
equipment for admission to the first cell; and, in response to the
request for admission to the first cell, admitting the user
equipment to the second cell based on the prediction of performance
of the first cell.
[0028] The admission of the user equipment to the second cell in
response to the request for admission to the first cell may be
based on the prediction of performance of both the first cell and
the second cell.
[0029] The user equipment may be admitted to the second cell in
response to the request for admission to the first cell without
being admitted to the first cell between the request for admission
to the first cell and the admission to the second cell.
[0030] The method may comprise receiving a request from the user
equipment for access to the second cell, and in response to the
request admitting the user equipment to the second cell based on
the statistics relating to past behavior of the user equipment in
the first cell.
[0031] The admission of the user equipment to the second cell may
be based on the prediction of performance of both the first cell
and the second cell. The determination of performance may comprise
a measure of at least one of: downlink throughput, downlink
latency, uplink throughput, and uplink latency.
[0032] The measure may comprise at least one of: a maximum downlink
throughput of the respective cell, a minimum downlink latency of
the respective cell, a maximum uplink throughput of the respective
cell, and a minimum uplink latency of the respective cell.
[0033] The measure may comprise a measure of an available air
interface resource of the respective cell. The measure may comprise
a measure of a hardware resource of the base station available for
the respective cell. The measure may comprise a measure of path
loss for the respective cell. The measure may comprise a power
limit of the respective cell. The measure may comprise an estimate
of noise and/or interference in the respective cell. In yet further
embodiments, the control of admission may be based on comparison of
the past behavior with the predicted performance.
[0034] According to another aspect of the present invention, there
is provided a multi-mode base station arranged to operate as a
plurality of cells, the plurality of cells comprising at least a
first cell and a second cell, and the base station comprising a
radio resource manager for controlling admission of a user
equipment to the cells, the radio resource manager being configured
to perform operations in accordance with any of the above
combinations of method features.
[0035] According to another aspect of the present invention, there
is provided a computer program product for controlling access to a
cell of a multi-mode base station, being a base station arranged to
operate as a plurality of cells, the plurality of cells comprising
at least a first cell and a second cell, and the computer program
product being embodied on a non-transient computer-readable medium
and configured so as when executed on a processor of the base
station to perform the operations of any of the above combinations
of method features.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] For a better understanding of the present invention and to
show how it may be put into effect, reference is made by way of
example to the accompanying drawings in which:
[0037] FIG. 1 is an illustration of a part of a wireless cellular
communication network, and
[0038] FIG. 2 is a flow chart of a method of controlling access to
a multi-mode base station.
DETAILED DESCRIPTION
[0039] FIG. 1 is a schematic diagram showing a part of a wireless
cellular communication network such as a 3G network. The network
comprises a user equipment (UE) 2 in the form of a mobile terminal,
such as a smart phone or other mobile phone, a tablet, or a laptop
or desktop computer equipped with a wireless data card. The network
further comprises a base station in the form of a femtocell 4, and
one or more further base stations 6. Each base station 4, 6
provides network coverage in the form of at least one respective
cell 4a, 4b, 6a.
[0040] Furthermore, the femtocell 4 is configured as a dual mode
femtocell. A dual-mode femtocell is a base station operating as two
logical cells 4a and 4b. These cells 4a, 4b may be configured to
operate according to different radio access technologies (RATs),
i.e. different telecommunication standards. For example one of the
dual cells may be arranged to operate according to a 3G standard
such as a Universal Mobile Telecommunications System (UMTS)
standard and the other of the dual cells may be arranged to operate
according to a 4G standard such as a Long Term Evolution (LTE)
standard. Alternatively, the cells 4a, 4b may be arranged to
operate according to the same RAT but in different frequency
sub-bands. The reach of the cells 4a, 4b does not necessarily
extend across exactly the same geographical area. Range is highly
dependent on RAT and frequency, e.g. cell 4a could be twice the
size of cell 4b. The arrangement shown in FIG. 1 is only schematic.
On a point of terminology, note that "base station" or "femtocell"
refers to the unit, whilst "cell" refers to the logical combination
of geographical coverage area and access technology or frequency
band (also note that in the context of the present application
"femtocell" refers to the base station unit rather than the cell).
As the two cells 4a, 4b are provided by the same base station unit
then they share the same cell center point, i.e. represent the same
geographical node of the network, and they also share at least some
of the same hardware resources. For example a dual-mode base
station 4 typically shares the same processor for both cells 4a,
4b, though typically not the same antenna. The dual cells 4a, 4b
typically also share other base-station functionality, such as
configuration management, synchronization and backhaul connection
(i.e. same connection to the next element up in the cellular
hierarchy).
[0041] The invention could apply equally to any multi-mode base
station, but by way of illustration the following embodiments are
described in relation to a dual-mode femtocell 4.
[0042] The user equipment 2 is arranged to be able to request
admission to a particular cell, and when it does so, e.g.
requesting admission to cell 4a, to request a particular quality of
service. For example it could request to be provided with at least
a certain uplink or downlink throughput, or to be provided with no
more than a certain uplink or downlink latency.
[0043] Each of the base stations comprises a radio resource manager
(RRM) arranged to receive the admission request from the UE and
decide whether to admit the user equipment 2 to the requested cell.
Conventionally this is done in the manner described in the
background section above by an independent RRM for each cell 4a,
4b, 6 respectively, including independent admission control for
each of the dual cells 4a, 4b. However, according to the present
invention there is provided a joint admission control mechanism
which shares information between the two or more cells 4a, 4b of a
multimode base station such as a dual-mode femtocell 4, i.e. shares
information relevant to service quality in the two or more cells.
This allows the radio resource manager for a requested cell 4a to
make a decision not only based on information of the requested cell
4a itself, but also based on information of the one or more
alternative other cells 4b of the multimode base station 4.
[0044] At a higher level of the cellular hierarchy the network may
comprise one or more higher-level controller stations, which may be
arranged to perform various further management functions. However,
the present invention is concerned with radio resource management
at the level of a multi-mode base station.
[0045] According to a first embodiment of the present invention,
the process of determining the throughput and/or other QOS
requirements of a UE 2 can be enhanced by storing long-term
statistics of UE behavior at the RRM. This allows the RRM to use
past-behavior to admit the UE to the most appropriate cell 4a, 4b
of a dual-mode femtocell 4.
[0046] The joint RRM can keep a history of the past connections for
a specific UE 2, and this can be used to determine the services and
throughput requirements that a specific UE typically uses. The
long-term parameters kept by the RRM can include the following:
[0047] Requested downlink throughput [0048] Requested uplink
throughput [0049] Utilized downlink throughput [0050] Utilized
uplink throughput [0051] Requested downlink latency [0052]
Requested uplink latency
[0053] For these parameters, one or more of the following
statistics can be collected: [0054] Long-term average values for
the parameters, giving a measure for basic prediction [0055]
Variation for the average over 24 hour periods, to find behavior
patterns across each day. [0056] Variation for the average over 7
days, to find behavior patterns across each week. [0057] Short-term
average values (over a few hours) to find local trends.
[0058] These parameters and statistics allow the RRM to predict the
throughput and/or other QOS requirements of a particular UE 2. The
RRM can then decide whether to continue admitting the UE 2 to the
cell 4a it is requesting, or whether to immediately admit the UE 2
to an alternative, more appropriate cell 4b. The use of joint RRM
combined with long-term statistics enables the best cell selection
to happen faster, preferably before the UE 2 indicates its QOS
requirements to the femtocell 4. In addition, moving the UE 2
between cells 4a, 4b at the start of the admission process requires
fewer signaling messages, thus reducing the signaling load on the
network.
[0059] A base station 4 may be configured to operate in one of a
plurality of different available modes. Closed access mode is where
the cell only provides a service to a subset of UE which are all
members of its closed subscriber group (CSG). Open access mode is
where the cell provides a service to any UE that are entitled to a
service from the network operator (i.e. this is identical mode used
in macro, micro and pico cells today). Hybrid access mode is where
the cell provides a service to any UE that are entitled to a
service from the network operator, but it also has a list of UE in
its CSG. This allows the cell to provide an improved service level
to these CSG (if it wants to).
[0060] Tracking UE parameters and statistics is most beneficial in
a femtocell 4 operating in either closed or hybrid mode where a
finite closed group of subscribers exist, which are expected to
regularly access the femtocell. This regular access allows reliable
predictions to be made.
[0061] The long-term prediction of statistics described above can
be either used standalone, or used to produce downlink throughput
and latency values (Thpt_DL_Req, Latency_DL_Req) and uplink
throughput and latency values (Thpt_UL_Req, Latency_UL_Req) to be
combined with a second embodiment of the invention, described
below.
[0062] According to a second embodiment of the present invention,
the selection of the best cell 4a, 4b of the dual mode femtocell 4
can be enhanced by predicting the throughput and latency of each
cell that can be achieved.
[0063] The downlink throughput and latency which is achievable can
be determined from: [0064] The static properties of the cell, for
example, minimum achievable latency and maximum achievable
throughput. [0065] The available air interface resources based on
the number of currently serviced UEs. For example, in LTE this
would be the number of resource blocks (RB), while for UMTS this
would be the number of codes available. [0066] The available
hardware resources for the cell which relate to the total number of
UEs supported, or the number of UEs supported each subframe (LTE)
or TTI (UMTS). [0067] The pathloss to the UE for this cell, which
can be very different for each cell. [0068] Any power limit applied
to the cell to protect neighbors in the same frequency sub-band.
This could be determined by pathloss to neighbors, downlink loading
information for the victim BS, proximity information for the victim
UE, and the operating mode for the femtocell (closed, hybrid,
open). [0069] Estimation, via sniffing, of the noise and
interference floor at the UE for this frequency sub-band.
[0070] Similarly, the uplink throughput and latency which is
achievable can be determined from: [0071] The static properties of
the cell, for example, minimum achievable latency and maximum
achievable throughput. [0072] The available air interface resources
based on the number of currently serviced UEs. For example, in LTE
this would be the number of resource blocks (RB), while for UMTS
this would be the number of codes available. [0073] The available
hardware resources for the cell which relate to the total number of
UEs supported, or the number of UEs supported each subframe (LTE)
or TTI (UMTS). [0074] The pathloss to the femtocell for this cell,
which can be very different for each cell. [0075] Any power limit
applied to the cell to protect neighbors in the same frequency
sub-band. This could be determined by pathloss to neighbors and
uplink loading information for the victim BS. [0076] Estimated of
the noise and interference floor at the femtocell for this
frequency sub-band.
[0077] These parameters can be used to determine a set of uplink
and downlink throughput and latency prediction for each cell,
denoted by (Thpt_DL_A, Thpt_DL_B, Latency_DL_A, Latency_DL_B) and
(Thpt_UL_A, Thpt_UL_B, Latency_UL_A, Latency_UL_B).
[0078] The UE is assigned to the cell with the throughput and
latency capabilities which most closely match the UE
requirements.
[0079] This prediction of achievable throughput and latency is
applicable to a femtocell operating in any of the three modes:
closed, hybrid or open.
[0080] This can be used standalone when the UE reports its QOS
requirements to the base-station, or combined with the UE
throughput and QOS prediction described in the first
embodiment.
[0081] In addition, if a cell is heavily loaded (congested), the
first and second embodiments of the invention can be used together
to form a prediction of throughput and latency of each of multiple
UEs, in each cell. Thus the UE is able to be optimally
redistributed at the dual-mode femtocell. For example, the
following values would be determined: [0082] UE1 in RATA, UE2 in
RAT A [0083] UE1 in RATA, UE2 in RATB [0084] UE1 in RATB, UE1 in
RATA [0085] UE1 in RATB, UE1 in RATB The most efficient combination
of UE and RAT can then be selected.
[0086] The flow chart of FIG. 2 illustrates an example of a
preferred decision making process which may be implemented in a
joint RRM of a multimode base station such as a dual mode femtocell
4. The process is preferably implemented in the form of computer
program code stored on a non-volatile storage medium of the base
station 4 (e.g. magnetic memory device such as a hard drive or an
electronic memory device such as a flash memory) and arranged for
execution on a processing apparatus of the base station (e.g.
single or multi core CPU). However, an implementation involving
dedicated hardware is not excluded.
[0087] At step S10 the RRM of the femtocell 4 receives a request
from the UE 2 for admission to a particular cell of the dual mode
femtocell 4, e.g. cell 4a.
[0088] At step S20, the RRM consults the past statistics it has
accumulated for the UE 2 when it was connected in the alternative
cell 4b (and preferably also the past statistics it has accumulated
for the UE 2 when it was connected in the requested cell 4a
itself). Generally the past statistics can be collected from either
cell or both cells. The RRM uses these statistics to produce
expected downlink throughput and/or latency values (Thpt_DL_Req,
Latency_DL_Req), and/or to produce uplink throughput and/or latency
values (Thpt_UL_Req, Latency_UL_Req). For reasons discussed above,
in a particularly preferred implementation this is done before the
UE 2 signals its own requested QOS requirement(s) to the femtocell
4. The values may be calculated from the statistics in response to
the request, or for faster response time may be maintained in
advance of the request.
[0089] At Step S30, the RRM consults its prediction of performance
of the alternative cell 4b (and preferably also its prediction of
performance of the requested cell 4a), i.e. its prediction of one
or more a priori properties that are a feature of the cell itself
rather than an a posteriori observed behavior of the UE 2 when
connected in the cell. Generally the performance can be determined
for either cell or both cells This results in a set of uplink
and/or downlink throughput and/or latency prediction values for
each cell, (Thpt_DL_A, Thpt_DL_B, Latency_DL_A, Latency_DL_B) and
(Thpt_UL_A, Thpt_UL_B, Latency_UL_A, Latency_UL_B). Again in a
particularly preferred implementation this is done before the UE 2
signals its own requested QOS requirement(s) to the femtocell 4;
and the values may be calculated from the statistics in response to
the request, or for faster response time may be maintained in
advance of the request.
[0090] At Step S40, the RRM compares the expected QOS
requirement(s) of the UE2 (Thpt_DL_Req, Latency_DL_Req,
Thpt_UL_Req, and/or Latency_UL_Req) with the predicted performance
value(s) of the alternative cell 4b (Thpt_DL_A, Thpt_DL_B,
Latency_DL_A, Latency_DL_B, Thpt_UL_A, Thpt_UL_B, Latency_UL_A,
and/or Latency_UL_B), and at step S50 determines based on the
comparison whether the UE 2 should be served by the alternative
cell. Preferably this involves also comparing the expected QOS
requirement(s) of the UE2 with the predicted performance value(s)
of the requested cell 4b, and determining whether the requested
cell 4a or the alternative cell 4b represents the best match to the
UE's needs.
[0091] If the RRM decides the UE 2 would not be better served by
the alternative cell 4b, it proceeds to step S60 where it admits
the UE 2 to the requested cell 4a. If on the other hand the RRM
decides the UE would be better served by the alternative cell 4b,
it proceeds to step S70 where it admits the UE 2 to the alternative
cell 4b. This may involve instructing the UE 2 to connect to the
alternative cell 4b or offering it the option of connecting to the
alternative cell 4b (the UE 2 could attempt a connection to a cell
6a of a different base station 6 in response to the offer).
[0092] In further embodiments, the RRM may receive requests from
multiple UEs 2 and may take into account the expected QOS
requirements and/or requested QOS for the multiple UEs, so as to
determine an optimal set of decisions balancing the needs of all
parties involved. The decision making process may also involve more
than two cells of a multimode femtocell or other such multimode
base station, e.g. by performing multiple instances of the
above-described comparison process for multiple alternative cells
and determining which comparison results in the best match.
[0093] It will be appreciated that the above embodiments have been
described only by way of example.
[0094] For instance, the above has been described in terms of
throughput and/or latency, but other information relevant to
service quality could also be used in addition or as an alternative
to these, e.g. error rate, loss or jitter.
[0095] Whilst it is preferred that the first and second embodiments
are used together, this is not necessarily the case. For example
the first embodiment could be used alone by taking the UE's past
experience of high throughput or low latency in an alternative one
of the multiple cells 4b as a trigger to admit the UE to that cell
4b instead of the requested cell 4a. Or in another example the
second embodiment could be used alone by comparing the predicted
performance of the alternative cell 4b with the UE's actual
requested QOS, instead of basing the comparison on the US's
expected QOS as would be determined from statistics of past
behavior according to the first embodiment.
[0096] Other variations may become apparent to a person skilled in
the art given the disclosure herein. The scope of the invention is
not limited by the described embodiments but only by the
claims.
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