U.S. patent application number 11/214071 was filed with the patent office on 2006-05-11 for power control.
This patent application is currently assigned to Nokia Corporation. Invention is credited to Harri Jokinen, Rami Vaittinen.
Application Number | 20060099986 11/214071 |
Document ID | / |
Family ID | 33523421 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060099986 |
Kind Code |
A1 |
Vaittinen; Rami ; et
al. |
May 11, 2006 |
Power control
Abstract
The invention relates to control of transmission power in
cellular networks, specifically in cells having transmitters in
several frequency bands. The invention allows the network to
control the maximum transmission power of a mobile station in more
than one frequency band.
Inventors: |
Vaittinen; Rami; (Littoinen,
FI) ; Jokinen; Harri; (Pertteli, FI) |
Correspondence
Address: |
HARRINGTON & SMITH, LLP
4 RESEARCH DRIVE
SHELTON
CT
06484-6212
US
|
Assignee: |
Nokia Corporation
|
Family ID: |
33523421 |
Appl. No.: |
11/214071 |
Filed: |
August 29, 2005 |
Current U.S.
Class: |
455/522 |
Current CPC
Class: |
H04W 52/367 20130101;
H04W 52/16 20130101; H04W 52/54 20130101 |
Class at
Publication: |
455/522 |
International
Class: |
H04B 7/00 20060101
H04B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 9, 2004 |
GB |
0424735.9 |
Claims
1. A method for controlling transmission power of a mobile station
communicating with a telecommunications network, comprising
determining a maximum output power level of a mobile station in a
first frequency band, transmitting a first parameter value
indicative of said maximum output power level of a mobile station
in a first frequency band, determining a maximum output power level
of the mobile station in at least one second frequency band, and
transmitting at least one second parameter value indicative of the
maximum output power level in association with said at least one
second frequency band.
2. A method as claimed in claim 1, comprising transmitting at least
one offset value.
3. A method as claimed in claim 2, comprising transmitting a
frequency band specific offset value for the at least one second
frequency band.
4. A method as claimed in claim 1, wherein each second transmission
power parameter value comprises an absolute value.
5. A method for determining maximum transmission power, comprising
receiving in mobile station a first transmission power parameter
value, determining an output power level of the mobile station in a
first frequency band based on said first transmission power
parameter value, receiving at least one second transmission power
parameter value, and determining a maximum output power level of
the mobile station in at least one second frequency band based on
said first transmission power parameter value and at least one
second transmission power parameter value.
6. A method as claimed in claim 5, wherein the step of determining
a maximum output power level in the at least one second frequency
band comprises determining a maximum output power level based on
said first transmission power parameter value and an offset
value.
7. A method as claimed in claim 6, comprising receiving a frequency
band specific offset value for at least one second frequency
band.
8. A method as claimed in claim 5, wherein the second transmission
power parameter value comprises an absolute value, and the step of
determining a maximum output power level in the second frequency
band comprises determining the maximum output power level based on
said first transmission power parameter value and said absolute
value.
9. A method as claimed in claim 8, wherein each band is assigned
with an absolute value.
10. A method for determining maximum transmission power, comprising
receiving a first parameter value, determining a maximum output
power level of a mobile station in a first frequency band based on
said first parameter value, receiving a second parameter value, and
determining a maximum output power level of the mobile station in a
second frequency band based on said second parameter value and a
predetermined offset value.
11. A method as claimed in claim 10, wherein the step of
determining the maximum output power level in the second frequency
band comprises determining a maximum output power level based on at
least one frequency band specific predetermined offset value.
12. A method as claimed in claim 10, comprising receiving a
parameter indicative of the maximum transmission power for a
frequency band as an offset from one second parameter value.
13. A method as claimed in claim 10, comprising receiving a
parameter indicative of the maximum transmission power for a
frequency band as an offset from said first parameter value.
14. A method as claimed in claim 10, comprising determining the
maximum power output levels in a communications system employing
General Packet Radio Service.
15. A method as claimed in claim 10, wherein the first parameter
value is associated with a upper band frequency and the second
parameter value is associated with a lower band frequency.
16. A method as claimed in claim 15, wherein the first parameter
comprises a MS_TXPWR_MAX_CCH parameter and the second parameter
comprises a LB_MS_TXPWR_MAX_CCH parameter.
17. A method for determining maximum transmission power in a mobile
station, comprising receiving a power control parameter value,
determining a maximum output power level of the mobile station in a
first frequency band based on said parameter value and a first
predetermined offset value, and determining a maximum output power
level of the mobile station in a second frequency band based on
said parameter value and a second predetermined offset value.
18. A method for determining maximum transmission power in a mobile
station, comprising: receiving a power control parameter value,
receiving a flag indicative how an output power is to be derived
from the received power control parameter, detecting that the flag
indicates multi-band operation, and determining a maximum output
power level of the mobile station in a frequency band by mapping
for a power control parameter value and a predetermined frequency
band specific offset value.
19. A node for a telecommunications network configured to determine
a maximum output power level of a mobile station in a first
frequency band, to transmit a first parameter value indicating said
maximum output power level of the mobile station, to determine a
maximum output power level of the mobile station in at least one
second frequency band, and to transmit at least one second
parameter value indicative the maximum output power level in
association with said at least one second frequency band.
20. A node as claimed in claim 19 being configured to transmit at
least one offset value.
21. A node as claimed in claim 20 being configured to transmit a
frequency band specific offset value for the at least one second
frequency band.
22. A node as claimed in claim 19, wherein each second transmission
power parameter value comprises an absolute value.
23. A mobile station configured to receive a first maximum
transmission power parameter value, to determine a maximum output
power level of the mobile station in a first frequency band based
on said first parameter value, to receive a second transmission
power parameter value, and to determine a maximum output power
level of the mobile station in at least one second frequency band
based on said first transmission power parameter value and at least
one second transmission power parameter value.
24. A mobile station as claimed in claim 23 being configured to
determine the maximum output power level of at least one second
frequency band based on said first transmission power parameter
value and an offset value.
25. A mobile station as claimed in claim 24, wherein the offset
value comprises a frequency band specific offset value.
26. A mobile station as claimed in claim 23, wherein the second
transmission power parameter value comprises an absolute value, the
mobile station being configured to determine a maximum output power
level in the second frequency based on said first transmission
power parameter value and said absolute value.
27. A mobile station configured to receive a first parameter value,
to determine a maximum output power level of the mobile station in
a first frequency band based on said first parameter value, to
receive a second parameter value, and to determine a maximum output
power level of the mobile station in a second frequency band based
on said second parameter value and a predetermined offset
value.
28. A mobile station as claimed in claim 27, the mobile station
being configured to determine the maximum output power level in the
second frequency band based on at least one frequency band specific
offset value.
29. A mobile station as claimed in claim 27, wherein the offset
value is an offset from one second parameter value.
30. A mobile station as claimed in claim 27, wherein the offset
value is an offset from said first parameter value.
31. A mobile station as claimed in claim 27, the mobile station
comprising a transmitter for communication with the
telecommunications system based on General Packet Radio
Service.
32. A mobile station as claimed in claim 27 being configured to
process a first parameter value that is associated with a upper
band frequency and a second parameter value that is associated with
a lower band frequency.
33. A mobile station as claimed in claim 32, wherein the first
parameter comprises a MS_TXPWR_MAX_CCH parameter and the second
parameter comprises a LB_MS_TXPWR_MAX_CCH parameter.
34. A mobile station configured to receive a power control
parameter value, to determine a maximum output power level of the
mobile station in a first frequency band based on said power
control parameter value and a first predetermined offset value, and
to determine a maximum output power level of the mobile station in
a second frequency band based on said power control parameter value
and a second predetermined offset value.
35. A node for a telecommunications network comprising at least
means for determining a maximum output power level of a mobile
station in a first frequency band, means for transmitting a first
parameter value indicating said maximum output power level of a
mobile station in a first frequency band, means for determining a
maximum output power level of a mobile station in a second
frequency band, and means for transmitting a second parameter value
indicative of the maximum output power level in association with
said second frequency band.
36. A mobile station comprising at least means for receiving a
first maximum transmission power parameter value, means for
determining a maximum output power level of the mobile station in a
first frequency band based on said first parameter value, and means
for determining a maximum output power level of the mobile station
in another frequency band based on a transmission power parameter
value and a frequency band specific offset value.
37. A mobile station as claimed in claim 36, comprising means for
receiving a second transmission power parameter value, wherein the
means for determining the maximum output power level in the other
frequency band are configured to determine the maximum power output
value based on said second transmission power parameter value and
the frequency band specific offset value.
38. A mobile station comprising at least means for receiving a
first parameter value, means for determining a maximum output power
level of the mobile station in a first frequency band based on said
first parameter value, means for receiving a second parameter
value, and means for determining a maximum output power level of
the mobile station in a second frequency band based on said second
parameter value and a predetermined offset value.
39. A mobile station, comprising at least means for receiving a
power control parameter value, means for determining a maximum
output power level of the mobile station in a first frequency band
based on said power control parameter value and a first
predetermined offset value, and means for determining a maximum
output power level of the mobile station in a second frequency band
based on said power control parameter value and a second
predetermined offset value.
40. A computer program embedded onto a computer-readable medium
comprising program code means configured to perform the steps of
claim 1, when the program is run on a computer.
41. A computer program embedded onto a computer-readable medium
comprising program code means configured to perform the steps of
claim 5, when the program is run on a computer.
42. A computer program embedded onto a computer-readable medium
comprising program code means configured to perform the steps of
claim 10, when the program is run on a computer.
43. A computer program embedded onto a computer-readable medium
comprising program code means configured to perform the steps of
claim 17, when the program is run on a computer.
44. A computer program embedded onto a computer-readable medium
comprising program code means configured to perform the steps of
claim 18, when the program is run on a computer.
Description
FIELD OF INVENTION
[0001] The invention relates to control of transmission power in
communications networks, specifically in systems wherein
transmitters operate in several frequency bands.
TECHNOLOGICAL BACKGROUND
[0002] A communications network is a facility which enables
communication between two or more entities such as user terminal
equipment (mobile or fixed) or other communication device, network
entities and other nodes. The communication may comprise, for
example, communication of voice, electronic mail (email), text
messages, data, multimedia and so on.
[0003] A communications network typically operates in accordance
with a given rules which set out what the various elements of a
system are permitted to do and how that should be achieved. For
example, a standard or specification may define if the user, or
more precisely user equipment, is provided with a circuit switched
(CS) bearer or a packet switched (PS) bearer, or both.
Communication protocols and/or parameters which should be used for
the connection are also typically defined. For example, the manner
in which communication should be implemented between the user
equipment and the elements of the communication networks is
typically based on a predefined communication protocol.
[0004] Access to the communication network may be provided by a
fixed line or wireless communication interface. Communication
systems providing wireless access enable at least some degree of
mobility for the users thereof. More advanced mobility support can
typically be added as an enhanced feature. An example of
communication networks providing wireless access is a public land
mobile network (PLMN). The public land mobile networks (PLMN) are
commonly based on cellular technology. In cellular systems, a base
transceiver station (BTS) or similar access entity services mobile
communication device or user equipment (UE) via a wireless
interface between these entities. These devices will in the
following be referred commonly as mobile stations. The
communication on the wireless interface between the mobile station
and elements of the communication network can be based on an
appropriate communication protocol. The operation of the base
station apparatus and other apparatus required for the
communication can be controlled by one or several control entities.
Non-limiting examples of PLMN systems include the GSM (Global
System for Mobile communications), the so called 2.5 generation
GPRS (General Packet Radio Service) or the third generation (3G)
networks such as WCDMA (Wideband Code Division Multiple Access) or
EDGE (Enhanced Data for GSM Evolution). Other examples of wireless
access technologies include various wireless local area networks
(WLANs) and satellite based systems.
[0005] The various control entities of a communication system may
be interconnected. One or more gateway nodes may be provided for
connecting a network to other communication networks, for example
to an IP (Internet Protocol) and/or other packet switched data
networks. In such arrangements, the communications network provides
user with access to external networks, hosts, or services offered
by specific service providers.
[0006] An example of the drawbacks of the current system will now
be described with reference to the GSM (Global System for Mobile
communication). The first GSM networks were designed for voice
services. When the use of the GSM data services started, it became
evident that the circuit switched bearer services were not
particularly well suited for certain types of applications with a
bursty nature. Therefore the new packet switched (PS) data
transmission service GPRS (General Packet Radio Service) was also
defined for packet services. GPRS is a packet radio network
utilising the GSM network, which endeavours to optimise data packet
transmission by means of GPRS protocol layers on the air interface
between a mobile station and a GPRS network.
[0007] According to third generation partnership project (3GPP)
standards, a GPRS mobile station (MS) can operate in one of three
modes of operation as disclosed for example by the standard
document 3GPP TS 23.060 version 6.5.0 of June 2004. These modes
are:
[0008] 1. Class A mode of operation: the MS is attached to the both
GPRS and other GSM services. The mobile user can make and/or
receive calls on the two services simultaneously e.g. having a
normal GSM voice call and receiving GPRS data packets at the same
time.
[0009] 2. Class B mode of operation: the MS is attached to the both
GPRS and other GSM services, but the MS can only operate on set of
services at a time.
[0010] 3. Class C mode of operation: the MS can only be attached
either to the GSM network or the GPRS network. The selection is
done manually and there are no simultaneous operations.
[0011] Multiple frequency bands have been specified for example in
the standard 3GPP TS 45.005 version 6.6.0 of July 2004 for GSM
operation. A multi-band GSM network may use frequencies from
multiple, typically two, different frequency bands. A single cell
of a GSM system may use frequencies from a single frequency band
only or it may use frequencies from multiple frequency bands. The
latter is often called "common BCCH cell" as the frequency
identifying the cell and broadcasting BCCH (broadcast control
channel) information is common for traffic channels on that cell,
where the traffic channels may be assigned on different frequency
bands.
[0012] According to the 3GPP standards, a mobile station (MS)
transmitting packet data to the network uses the output power given
by the formula in the sub-clause 10.2.1 of the standard
specification 3GPP TS 45.008 version 6.0.8 of July 2004. According
to that sub-clause the radio frequency (RF) output power, P.sub.CH,
to be employed by the mobile station on each individual uplink
Packet Data Channel (PDCH) shall be:
P.sub.CH=min(.GAMMA..sub.0-.GAMMA..sub.CH-.alpha.*(C+48), PMAX),
[0013] where [0014] .GAMMA..sub.CH is an MS and channel specific
power control parameter, sent to the MS in an radio link control
(RLC) control message (see 3GPP TS 44.060). .GAMMA. 0 = 39 .times.
.times. dB .times. .times. m .times. .times. for .times. .times.
GSM .times. .times. 400 , GSM .times. .times. 700 , GSM .times.
.times. 850 .times. .times. and .times. .times. GSM .times. .times.
900 = 36 .times. .times. dB .times. .times. m .times. .times. for
.times. .times. DCS .times. .times. 1800 .times. .times. and
.times. .times. PCS .times. .times. 1900 ##EQU1## [0015] .alpha. is
a system parameter, broadcast on PBCCH or optionally sent to MS in
an RLC control message (see 3GPP TS 44.018 and 3GPP TS 44.060).
[0016] C is the normalised received signal level at the MS as
defined in sub-clause 10.2.3.1 of the above referred standard
specification 3GPP TS 45.008. [0017] PMAX is the maximum allowed
output power in the cell, [0018] which is [0019]
GPRS_MS_TXPWR_MAX_CCH if present, [0020] MS_TXPWR_MAX_CCH
otherwise.
[0021] As can be seen the key factor is the PMAX, since
nevertheless what the calculation gives the mobile station shall
use the lowest of the two;
(.gamma..sub.0-.GAMMA..sub.CH-.alpha.*(C+48) or PMAX given as the
network delivered parameter. PMAX parameter is broadcast on a
broadcast control channel (BCCH) in system information 13 (SI3) and
in system information 14 (SI4) and respectively on packet broadcast
control channel (PBCCH) in packet system information 13 (PSI3),
see, for example, 3GPP TS 44.018 version 6.8.0 of July 2004 and
3GPP TS 44.060 version 6.8.0 of July 2004. The formula and the
comparison work well when the packet resources are allocated in the
same band than BCCH and/or PBCCH.
[0022] The exemplifying Table 1 of FIG. 1 presents the nominal
output powers of GSM 400, GSM 900, GSM 850 and GSM 700 bands
according to GSM standards. If the MS is packet idle mode listening
BCCH (in 900 MHz band) intermittently and it receives the
MS_TXPWR_MAX_CCH parameter with value 8 then the nominal output
power level is 27 dBm. Then the MS requests packet resources and
the network allocates resources on 1800 MHz. As can be seen from
the second table in the following, value 8 denotes 14 dBm on the
1800 MHz band instead of 27 dBm on 900 MHz band. Too low output
power level may lead to a poor signal quality and respectively too
high power level may cause unnecessary interference.
[0023] Table 2 of FIG. 2 presents nominal output powers for DCS
1800 band as specified in 3GPP TS 45.005 version 6.6.0 of July
2004.
[0024] These arrangements have certain problems. The mobile
station's maximum output power is based on parameters received in
system information messages on (P)BCCH channel while in the packet
idle mode. When the network allocates packet resources on a
different frequency band than the common (P)BCCH channels the
network may have difficulties in setting the correct maximum output
power for the mobile station. The network cannot optimise the
maximum power for each frequency band separately in a common BCCH
cell and especially, because of the different mapping of power
control levels on different frequency bands, the network cannot set
the same dBm value, or a value that reflects the frequency band
specific path loss for each frequency band on that cell, for the
maximum output power on each frequency band.
SUMMARY OF THE INVENTION
[0025] Embodiments of the present invention aim to overcome one or
several of the above problems.
[0026] According to one aspect of the invention there is provided a
method for controlling transmission power of a mobile station
communicating with a telecommunications network. The method
comprises determining a maximum output power level of a mobile
station in a first frequency band, transmitting a first parameter
value indicative of said maximum output power level of a mobile
station in a first frequency band, determining a maximum output
power level of the mobile station in at least one second frequency
band, and transmitting at least one second parameter value
indicative of the maximum output power level in association with
said at least one second frequency band.
[0027] According to another aspect of the invention, there is
provided a method for determining maximum transmission power. The
method comprises receiving in mobile station a first transmission
power parameter value, determining an output power level of the
mobile station in a first frequency band based on said first
transmission power parameter value, receiving at least one second
transmission power parameter value, and determining a maximum
output power level of the mobile station in at least one second
frequency band based on said first transmission power parameter
value and at least one second transmission power parameter
value.
[0028] According to a yet another aspect of the invention, there is
provided a method for determining maximum transmission power. The
method comprises receiving a first parameter value, determining a
maximum output power level of a mobile station in a first frequency
band based on said first parameter value, receiving a second
parameter value, and determining a maximum output power level of
the mobile station in a second frequency band based on said second
parameter value and a predetermined offset value.
[0029] According to a yet another aspect of the invention, a method
for determining maximum transmission power in a mobile station is
provided. The method comprises receiving a power control parameter
value, determining a maximum output power level of the mobile
station in a first frequency band based on said parameter value and
a first predetermined offset value, and determining a maximum
output power level of the mobile station in a second frequency band
based on said parameter value and a second predetermined offset
value.
[0030] According to a still another aspect of the invention, a
method for determining maximum transmission power in a mobile
station is provided. The method comprises receiving a power control
parameter value, receiving a flag indicative how an output power is
to be derived from the received power control parameter, detecting
that the flag indicates multi-band operation, and determining a
maximum output power level of the mobile station in a frequency
band by mapping for a power control parameter value and a
predetermined frequency band specific offset value.
[0031] There is also provided a node for a telecommunications
network configured to determine a maximum output power level of a
mobile station in a first frequency band, to transmit a first
parameter value indicating said maximum output power level of the
mobile station, to determine a maximum output power level of the
mobile station in at least one second frequency band, and to
transmit at least one second parameter value indicative the maximum
output power level in association with said at least one second
frequency band.
[0032] According to an aspect, there is provided a mobile station
configured to receive a first maximum transmission power parameter
value, to determine a maximum output power level of the mobile
station in a first frequency band based on said first parameter
value, to receive a second transmission power parameter value, and
to determine a maximum output power level of the mobile station in
at least one second frequency band based on said first transmission
power parameter value and at least one second transmission power
parameter value.
[0033] According to another aspect, a mobile station is configured
to receive a first parameter value, to determine a maximum output
power level of the mobile station in a first frequency band based
on said first parameter value, to receive a second parameter value,
and to determine a maximum output power level of the mobile station
in a second frequency band based on said second parameter value and
a predetermined offset value.
[0034] In accordance with a yet another aspect a mobile station is
configured to receive a power control parameter value, to determine
a maximum output power level of the mobile station in a first
frequency band based on said power control parameter value and a
first predetermined offset value, and to determine a maximum output
power level of the mobile station in a second frequency band based
on said power control parameter value and a second predetermined
offset value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Embodiments of the present invention will now be described
by way of example with reference to the accompanying drawings, in
which:
[0036] FIGS. 1 and 2 show nominal output power Tables for
exemplifying telecommunications systems,
[0037] FIG. 3 illustrates a method according to an advantageous
embodiment of the invention, and
[0038] FIG. 4 illustrates a method according to a further
advantageous embodiment of the invention, and
[0039] FIG. 5 illustrates various further embodiments of the
invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0040] FIG. 3 illustrates a method in accordance with an embodiment
for a network node of a telecommunications network for controlling
transmission power of mobile stations communicating with the
telecommunications network. A maximum output power level of a
mobile station is first determined at 110 in a first frequency
band, where after a first parameter value indicating said maximum
output power level of a mobile station is transmitted at 120 in a
first frequency band. A maximum output power level of a mobile
station in a second frequency band is also determined at 130, where
after a second parameter value indicating an offset from said
maximum output power level of a mobile station is transmitted in
the first frequency band.
[0041] FIG. 4 illustrates a method in accordance with another
embodiment for determining maximum transmission power in a mobile
station of a telecommunications network. In the embodiment a first
maximum transmission power parameter value is received at 210,
where after a maximum output power level of the mobile station in a
first frequency band is determined at 220 based on said first
parameter value. A second transmission power parameter value can be
received at 230, where after a maximum output power level of the
mobile station in a second frequency band can be determined at 240
based on said first and second transmission power parameter
values.
[0042] FIG. 5 illustrates schematically a telecommunications system
wherein the various embodiments may be implemented. FIG. 5
illustrates a mobile station 300, a cellular network 340, and a
network element 330 of the cellular network 340. In the example of
FIG. 5, the network element 330 is a base station.
[0043] A cellular network is typically arranged to serve a
plurality of mobile stations, via a wireless interface between the
mobile stations and base stations of the communication system. The
cellular communication network may provide packet switched data
transmission in the packet switched domain between a support node
and a mobile station. The network in turn may be connected to
external networks, for example the Internet, via an appropriate
gateway to allow communication between mobile stations and external
networks. In addition to at least one gateway, a network may
comprise also other nodes, for example radio network and/or base
station controllers.
[0044] The base station 330 is arranged to transmit signals to and
receive signals from the mobile station 300, via respective
wireless interfaces. Correspondingly, each mobile station is able
to transmit signals to and receive signals from the base stations
via the wireless interface.
[0045] A mobile station within an access network may communicate
via radio network channels which are typically referred to as radio
bearers. Each mobile station such may have one or more radio
channels open at any one time. The mobile station can be used for
various tasks such as making and receiving phone calls, for
receiving and sending data from and to a network and for
experiencing, for example, multimedia or other content. The mobile
station is typically provided with a processor and memory for
accomplishing these tasks. The operation of the mobile station may
be controlled by means of a suitable user interface such as key
pad, voice commands, touch sensitive screen or pad, combinations
thereof or the like. A mobile station also typically comprise
components such as an antenna, a transmitter, a power source,.
Various components of a mobile station known to a man skilled in
the art, wherefore they are not described in detail in this
application. Non-limiting examples of the mobile stations include a
personal computer, a personal data assistant (PDA), a mobile phone,
a portable computer, and various combinations thereof.
[0046] FIG. 5 illustrates certain details of a mobile station 300
in accordance with an embodiment. The mobile station 300 comprises
a receiver 310 for receiving a first maximum transmission power
parameter value and a second transmission power parameter value.
The mobile station also comprises a controller 320 for determining
a maximum output power level of the mobile station in a first
frequency band based on said first parameter value, and for
determining a maximum output power level of the mobile station in a
second frequency band based on said first and second transmission
power parameter values. It is noted that these component may be
provided separately for the first and second frequency bands, if
this is deemed appropriate.
[0047] In an embodiment of the invention, the method can be
implemented by means of software programs executed by a processor
in the mobile station. In such an implementation, the receivers 310
can be implemented using computer software code means which are
arranged to receive data and store received parameter values, while
said controllers 320 can be implemented using computer software
code means which perform said determinations.
[0048] FIG. 5 also illustrates some further details of the network
element 330, which comprises an implementation of an advantageous
embodiment of the invention. As shown in FIG. 5, the network
element 330 comprises a controller 332 for determining a maximum
output power level of a mobile station in a first frequency band, a
transmitter 334 for transmitting a first parameter value indicating
said maximum output power level of a mobile station in a first
frequency band, a controller 332 determining a maximum output power
level of a mobile station in a second frequency band, and a
transmitter 334 for transmitting a second parameter value
indicating an offset from said maximum output power level of a
mobile station in a first frequency band.
[0049] In a further advantageous embodiment of the invention, the
invention can be implemented using software in the network element.
In this embodiment, the controllers 332 can be implemented using
computer software code means in the network element. Also the
transmitters 334 can be implemented as computer software code means
causing the transmission of said values from the processor unit of
the network element.
[0050] According to an embodiment of the invention, existing
parameters MS_TXPWR_MAX_CCH and GPRS_MS_TXPWR_MAX_CCH (if PBCCH is
present) may be used to control maximum output power level of upper
bands (e.g. DCS 1800 MHz 1900 MHz) and a new parameter may used to
control maximum output power level of lower bands (e.g. GSM 400,
GSM 900, GSM 850 and GSM 700 bands). This new parameter, here
called the TBF_MS_TXPWR_MAX parameter, may be used to represent an
offset from the upper band value.
[0051] According to a further embodiment of the invention, the
TBF_MS_TXPWR_MAX parameter represents an absolute value.
[0052] The TBF_TXPWR_MAX parameter may be specified independently
band by band.
[0053] The TBF_MS_TXPWR_MAX parameter can be transmitted in SI13
rest octets information element (IE) sent on BCCH. In a PBCCH
channel, the parameter can be transmitted in a PACKET SYSTEM
INFORMATION 1 (PSI1) message.
[0054] According to an embodiment, existing parameters, for example
MS_TXPWR_MAX_CCH and GPRS_MS_TXPWR_MAX_CCH (if PBCCH is present),
may be used as a parameter to control maximum output power level of
an upper frequency band (e.g. 1800 MHz), and a first new parameter
may be used to control maximum output power level for one of the
lower bands (e.g. 900 MHz). Maximum output power levels for other
bands may be specified using frequency band specific predetermined
fixed offset parameters. These parameters may indicate the maximum
transmission power for each band as an offset from said first new
parameter. Alternatively, the offset may be from the parameter
associated with said upper frequency band, or from another further
parameter. There can be a separate individually assigned
predetermined offset parameter for each of a plurality of frequency
bands.
[0055] For example, in a GPRS system the above parameters could be
such that a `MS_TXPWR_MAX_CCH` corresponds to the first parameter,
and `LB_MS_TXPWR_MAX_CCH` corresponds to the second parameter.
[0056] For example, this mapping can be achieved by setting code
point 1 for MS_TXPWR_MAX_CCH parameter (and respectively for
GPRS_MS_TXPWR_MAX_CCH if PBCCH is present) and for a new parameter
code point 10 (assuming that existing mapping table specified in
3GPP TS 45.005 is used also for a new parameter). The corresponding
mapping of the maximum output power may then be: TABLE-US-00001
Frequency band offset 1800 MHz 28 dBm 900 MHz 23 dBm 450 MHz 23 dBm
- 6 dB = 17 dBm
[0057] Possible predetermined fixed offset values for different
lower band frequencies may be set for example as follows (in the
example relative to the 900 MHz band): TABLE-US-00002 Frequency
band offset 900 MHz 0 dB 850 MHz 0 dB 700 MHz -2 dB 400 MHz -6
dB
[0058] Use of individually set offsets for different frequency
bands has the advantage that it can enable optimal maximum output
power level setting for all lower bands supported in a given
cell.
[0059] According to a further embodiment, maximum output power on
different bands is controlled by predefining a frequency band
specific offset for each frequency band in use at a cell,
transmitting a power control parameter, and calculating the maximum
output power value for transmissions on a specific frequency band
from said power control parameter and the predefined offset value
corresponding to this specific frequency band.
[0060] The frequency band specific offset could be defined for all
bands in use at a base station, e.g. as follows using 900 MHz band
as a reference band: TABLE-US-00003 Frequency band offset 1900 MHz
+6 dB 1800 MHz +6 dB 900 MHz 0 dB 850 MHz 0 dB 700 MHz -2 dB 400
MHz -6 dB
[0061] This embodiment can advantageously be implemented by
arranging a base station transmit a power control parameter
according to prior art, and a second power control parameter. In
such an implementation, mobile stations which are incapable of
performing the inventive method obey the power control parameter
transmitted according to prior art, and mobile stations which can
perform according to the invention can use the second power control
parameter and the predefined offset values for determining maximum
transmission power levels in different frequency bands.
[0062] According to a still further embodiment of the invention,
maximum transmission powers in different frequency bands are
controlled by storing predetermined offset values in a mobile
station and transmitting an indication from the network to the
mobile station that these offset values are to be applied. As a
response to reception of said indication, it is possible to
determine the maximum transmission power in a frequency band on the
basis of a maximum transmission power parameter for a predetermined
frequency band (such as, for example, the MS_TXPWR_MAX_CCH or
GPRS_MS_TXPWR_MAX_CCH parameter) and the offset value corresponding
to the frequency band. The transmission power parameter may be
defined as for specific predetermined frequency bands. A frequency
band specific offset to this value may then be applied to other
bands. This embodiment has advantage in that the indication that
the offset values are to be applied can be as simple as a one-bit
flag transmitted from the base station to the mobile station.
Because of this the implementation of this embodiment adds very
little load on the air interface.
[0063] The above described embodiments provide several advantages.
Accurate control of maximum output power on a common BCCH cell may
be allowed. The behaviour of legacy terminals can be maintained as
optimal as possible. The link budget properties of different bands
can be taken into account without having a specific maximum output
power parameter defined for each band separately. The number of
bits used for signalling can be kept low.
[0064] It is noted that while the preceding description illustrates
various embodiments of the invention with reference to cellular
telecommunications systems such as the GSM and 3G systems, the
invention is not limited to cellular systems, but can be
implemented in different types of communication systems as well.
The embodiments are applicable to packet switched access and
circuit switched access.
[0065] It is also noted herein that while the above describes
exemplifying embodiments of the invention, there are several
variations and modifications which may be made to the disclosed
solution without departing from the scope of the present invention
as defined in the appended claims.
* * * * *