WO1995025365A2 - A method for estimating received power and a receiver - Google Patents
A method for estimating received power and a receiver Download PDFInfo
- Publication number
- WO1995025365A2 WO1995025365A2 PCT/FI1995/000141 FI9500141W WO9525365A2 WO 1995025365 A2 WO1995025365 A2 WO 1995025365A2 FI 9500141 W FI9500141 W FI 9500141W WO 9525365 A2 WO9525365 A2 WO 9525365A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- base station
- received
- signal
- mobile station
- receiver
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000005259 measurement Methods 0.000 claims abstract description 52
- 230000001413 cellular effect Effects 0.000 claims abstract description 11
- 238000001914 filtration Methods 0.000 claims description 6
- 230000002452 interceptive effect Effects 0.000 claims description 5
- 101150080339 BTS1 gene Proteins 0.000 abstract description 5
- 230000005540 biological transmission Effects 0.000 description 9
- 239000011159 matrix material Substances 0.000 description 9
- 239000013598 vector Substances 0.000 description 6
- 238000012545 processing Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 238000007619 statistical method Methods 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000005562 fading Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000012731 temporal analysis Methods 0.000 description 1
- 230000036962 time dependent Effects 0.000 description 1
- 238000000700 time series analysis Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
- H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
- H04W36/302—Reselection being triggered by specific parameters by measured or perceived connection quality data due to low signal strength
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
- H04W36/0085—Hand-off measurements
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
Definitions
- the invention relates to a method for estimating received power in a cellular radio system comprising in each cell at least one base station communicating with mobile stations within its coverage area, in which system mobile stations measure strength of the signal received from the base station, and report the measurement results to the base station equipment, and the base station measures strength of the signal received from mobile stations.
- both the base station and the mobile station measure the power level of the received signal.
- the mobile station reports the measurement results to the base station, which transmits power adjustment commands to the mobile station, and, as the signal weakens, takes the handover decision.
- the power level of the received signal is a continuously changing variable, and instantaneous measurement results contain some inaccuracy, such as measurement noise and time-dependent error caused by the actual measurement devices. Therefore, the measurement results are not useful as such, but they must be processed in some way to minimize the effect of measurement errors.
- measurement results of received power are filtered, i.e. averaged, within a time window of a certain size.
- the worst error peaks can be eliminated from the measurement results.
- the method has the advantage of being simple to implement, but it has the drawback of being unadaptable to the behaviour of rapidly changing data.
- a way to improve said method is to adjust the width of the time window, but this approach is also unable to model a changing signal sufficiently well, and thus not useful in predicting the future behaviour of the signal.
- the invention also relates to a receiver, for use in a cellular radio system comprising in each cell at least one base station communicating with mobile stations within its coverage area, in which system mobile stations measure strength of the signal received from the base station, and report the measurement values to the base station equipment, and in which the base station measures strength of the signal received from mobile stations, said equipment comprising means for recording measurement results obtained from mobile stations.
- the receiver is characterized by comprising means for forming with the aid of the received measurement results, a model describing the dynamic behaviour of the signal for the received power on each connection, taking into account at least one signal interfering with the connection, and means for utilizing said predicted data for power adjustment, as well as for taking handover decisions.
- the solution in accordance with the present invention enables improvement of power adjustment especially in a microcell environment in street corner situations.
- a mobile station approaching from an intersecting street must rapidly adjust its signal strength in accordance with instructions from a new base station. Rapid power adjustment enabled by the invention may significantly improve the operation of power adjustment in a situation of this kind.
- Figure 1 shows a part of a cellular radio system, in which the method of the invention can be applied
- Figure 2 illustrates operation of the method of the invention in a power adjustment situation compared with prior art methods
- Figure 3 illustrates a street corner situation, in which rapid power adjustment is needed
- Figure 4 illustrates the structure of a receiver of the invention.
- a model describing dynamic behaviour of the signal is formed from the measurement results of the received signal.
- processing of the measurement results is illustrated with Kalman filtering, but other statistical methods may also be used for processing the measurement results in the method of the invention.
- Kalman filtering is an optimal time-domain prediction method for linear models. The accuracy of linear models is sufficient for short-term predictions.
- a so-called state space model is formed in connection with Kalman filtering on the basis of the measurement results.
- the equations of the state space model may be expressed as the observation equation (1) :
- the method of the invention will be set out in connection with a base station; however, the invention is not limited to it.
- the method can naturally also be applied in the receiver of a mobile station.
- Figure 1 thus illustrates a cellular network system, in which the method of the invention can be applied.
- the figure shows two base stations, BTS1 and BTS2, each base station serving its own coverage area.
- the base stations are connected to a base station controller BSC via digital transmission links 10.
- a mobile station MS is located in the area between two base stations, in which it is able to receive signals 11, 12 from both base stations.
- the base station controller analyses the measurement results from the mobile station. Kalman filter estimators now have the form
- t-l) Bx(t-l
- t) x(t
- the transition matrix B is determined in each cell on the basis of the dynamic process of the channel.
- Cells of various kinds can be modelled by using the above matrix.
- the matrix can model e.g. exponential fading of the signal as a function of distance.
- the dimension of the matrix determines the order of the state space model. In the above example (formulas 3 and 4), the order is two.
- the model can be determined by examining the measurement results.
- Known link parameters, such as Doppler spread can be utilized in the selection of the model. When Doppler spread is small, it is known that the mobile station is moving slowly, which is often the case in an urban area, and the dimension of the matrix can thus be selected to be small.
- the gain matrix K(t) can be calculated recursively based on a prediction error covariance matrix.
- t-l) has been calculated directly on the basis of the previous predicted value, whereas the best estimator x(t
- the base station is capable of optimal adjustment of the transmission power of the mobile station by estimating measured values.
- the invention can be applied specifically in a CDMA cellular radio network, in which the base station must, in order to maximize the capacity of the cell, adjust the transmission power of mobile stations so that it receives all stations with the same signal strength. In this case, the accurate and rapid power adjustment enabled by the method of the invention is particularly advantageous.
- the invention can also be advantageously applied in cellular radio systems in which interference within the same channel occurs. For instance, if 8 frequency re-use in TDMA systems is increased in order to achieve a higher frequency efficiency, interference within the same frequency channel may occur.
- Figure 2 illustrates the accuracy of power adjustment based on estimates calculated from the measurement results, compared with prior art methods.
- the horizontal axis represents time and the vertical axis represents power value.
- a value 21 obtained with a conventional non-predictive method, as well as signal estimates 22 and 23 obtained with two different estimation methods have been drawn on the actual signal 20.
- the predictive one step estimate 22 provides a more accurate value of the signal than the non-predictive method 21.
- An even more accurate estimate of the signal can be obtained with the linear estimate 23.
- the situation shown in figure 2 has been simulated by using the frequency of 1.8 GHz in a 2-path Rayleigh channel; the velocity of the mobile station is assumed to be 25 km/h, and power adjustment is carried out at intervals of 2 irts.
- the invention may also be applied in the case of handover in the boundary area between the coverage areas of two base stations.
- the base station controller BSC can estimate an optimal point of time for handover in a situation as shown in figure 1.
- the base station controller can predict the signal behaviour in a fading channel, and initiate handover procedures more rapidly compared with prior art methods.
- Figure 3 illustrates a situation in which a mobile station which is communicating with a base station BTS1 comes to a street corner, and to the coverage area of a base station BTS2.
- the distance dl of the base station BTS1 from the street corner is longer than that d2 of the base station BTS2.
- a system in which both base stations transmit by using the same frequency band which is the case e.g. in a cellular radio system applying the CDMA-multiple access method.
- the mobile station controlled by base station BTS1, transmits by using a high transmit power.
- the mobile station comes to a street corner, its transmission interferes with base station BTS2 with its high transmit power.
- the mobile station must therefore rapidly reduce its transmit power and change over to the coverage area of BTS2.
- the predictive method of the invention can be employed in such a way that when approaching the street corner, the mobile station notices that the transmit power of base station BTS2 gradually increases.
- the signal of BTS2 is estimated, its behaviour can be predicted, and the necessary handover can thus be initiated rapidly as soon as it becomes possible.
- interference caused to other connections in the cell is smaller compared with prior art methods.
- the method can also be used for estimating missing measurement values of the mobile station. Measurement results may be destroyed e.g. due to interference on the radio path when the results are transmitted to a base station. Missing measurement values can be estimated with recursive calculations by using equations of the type described above. Furthermore, the method can be employed for estimating reliability of the measurement results received from a mobile station. If a measurement result received from a mobile station notably deviates from the estimated value, it can be assumed that an error has occurred in data transmission, and that the transmitted measurement result perhaps is not correct.
- a model suitable for the cell is first selected.
- previously measured power values are used as the basis for the selection of the matrices B and A for the above shown formulas (1), (2) and (5) .
- estimate algorithms may be calculated either forwards or recursively, depending on whether a signal to be received is predicted, or whether missing measurement values are estimated. Estimates obtained in this way can further be processed as true power values in handover or power adjustment algorithms. Kalman filtering and calculations pertaining to it are described in greater detail in Robert Schu way: Applied statistical time series analysis, Prentice Hall, 1988, and P. Strobach: Linear Prediction Theory, Springer Verlag 1990, which are incorporated herein by reference.
- one or more interfering signals are also taken into account besides the actual signal.
- spreading codes used for various connections are not fully independent, and thus correlation occurs between connections.
- FIG. 4 is a block diagram illustrating the structure of a receiver in which the method of invention is applied.
- the receiver comprises an antenna 30, means 31 for switching the signal to the baseband, means 32 for deinterleaving the signal, and means 33 for demodulating the signal.
- the receiver further comprises means 34 for controlling the operation of other blocks and the receiver.
- the receiver naturally comprises also other components, such as converters and filters, and depending on the nature of the receiver, also a speech decoder, but, since these components are unessential to the present invention, they are not shown in this illustration.
- the receiver in which the method of the invention is applied comprises means 34 for estimating the received signal on the basis of the measurement results obtained by the mobile station and the base station.
- Means 34 can be implemented e.g. by means of a digital signal processor.
Abstract
Description
Claims
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE69523902T DE69523902T2 (en) | 1994-03-17 | 1995-03-16 | METHOD AND RECEIVER FOR ESTIMATING THE RECEIVED PERFORMANCE |
US08/549,804 US5845208A (en) | 1994-03-17 | 1995-03-16 | Method for estimating received power and a receiver |
EP95912271A EP0750824B1 (en) | 1994-03-17 | 1995-03-16 | A method for estimating received power and a receiver |
AT95912271T ATE208983T1 (en) | 1994-03-17 | 1995-03-16 | METHOD AND RECEIVER FOR ESTIMATING RECEIVED POWER |
AU19519/95A AU686346B2 (en) | 1994-03-17 | 1995-03-16 | A method for estimating received power and a receiver |
JP7523865A JPH09510335A (en) | 1994-03-17 | 1995-03-16 | Method and receiver for estimating received power |
NO954640A NO954640L (en) | 1994-03-17 | 1995-11-16 | Procedure for estimating received power as well as receiver |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI941268 | 1994-03-17 | ||
FI941268A FI941268A (en) | 1994-03-17 | 1994-03-17 | A method for evaluating the received power and a receiver |
Publications (2)
Publication Number | Publication Date |
---|---|
WO1995025365A2 true WO1995025365A2 (en) | 1995-09-21 |
WO1995025365A3 WO1995025365A3 (en) | 1995-11-16 |
Family
ID=8540339
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FI1995/000141 WO1995025365A2 (en) | 1994-03-17 | 1995-03-16 | A method for estimating received power and a receiver |
Country Status (10)
Country | Link |
---|---|
US (1) | US5845208A (en) |
EP (1) | EP0750824B1 (en) |
JP (1) | JPH09510335A (en) |
CN (1) | CN1080957C (en) |
AT (1) | ATE208983T1 (en) |
AU (1) | AU686346B2 (en) |
DE (1) | DE69523902T2 (en) |
FI (1) | FI941268A (en) |
NO (1) | NO954640L (en) |
WO (1) | WO1995025365A2 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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DE19535021A1 (en) * | 1995-09-21 | 1997-07-10 | Joerg Dr Arnold | Mobile digital radio signal transceiver |
FR2749994A1 (en) * | 1996-06-18 | 1997-12-19 | Dalsace Eric | Child surveillance system for use by adult in charge of child |
FR2772540A1 (en) * | 1997-12-16 | 1999-06-18 | Sagem | METHOD FOR OPERATING A MOBILE TELEPHONE OF A RADIO COMMUNICATION NETWORK IN ASSOCIATION WITH A TELEPHONE CONNECTED BY WIRE TO THE TELEPHONE NETWORK, AND INTEGRATED SET OF SUCH NETWORKS |
US6026081A (en) * | 1996-07-05 | 2000-02-15 | Nec Corporation | Method of controlling power on forward link in a cellular |
WO2001049053A1 (en) * | 1999-12-28 | 2001-07-05 | Matsushita Electric Industrial Co., Ltd. | Base station device and transmission power control method |
EP2237469A1 (en) | 2009-04-03 | 2010-10-06 | TELEFONAKTIEBOLAGET LM ERICSSON (publ) | Method and device for measuring a received signal power in a mobile communication system |
Families Citing this family (25)
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TW347616B (en) * | 1995-03-31 | 1998-12-11 | Qualcomm Inc | Method and apparatus for performing fast power control in a mobile communication system a method and apparatus for controlling transmission power in a mobile communication system is disclosed. |
US6977967B1 (en) | 1995-03-31 | 2005-12-20 | Qualcomm Incorporated | Method and apparatus for performing fast power control in a mobile communication system |
JP2868481B2 (en) * | 1996-10-24 | 1999-03-10 | 埼玉日本電気株式会社 | Radio with automatic response function |
US6307849B1 (en) * | 1997-09-08 | 2001-10-23 | Qualcomm Incorporated | Method and system for changing forward traffic channel power allocation during soft handoff |
US6175745B1 (en) * | 1997-12-24 | 2001-01-16 | Telefonaktiebolaget Lm Ericsson | Initial transmit power determination in a radiocommunication system |
US6434386B1 (en) * | 1998-12-31 | 2002-08-13 | Telefonaktiebolaget L M Ericsson (Publ) | Method and system for monitoring power output in transceivers |
US6975666B2 (en) * | 1999-12-23 | 2005-12-13 | Institut National De La Recherche Scientifique | Interference suppression in CDMA systems |
US6597723B1 (en) * | 2000-03-21 | 2003-07-22 | Interdigital Technology Corporation | Weighted open loop power control in a time division duplex communication system |
US6600772B1 (en) * | 2000-03-21 | 2003-07-29 | Interdigital Communications Corporation | Combined closed loop/open loop power control in a time division duplex communication system |
US6603797B1 (en) * | 2000-03-22 | 2003-08-05 | Interdigital Technology Corporation | Outer loop/weighted open loop power control in a time division duplex communication system |
GB2363557A (en) * | 2000-06-16 | 2001-12-19 | At & T Lab Cambridge Ltd | Method of extracting a signal from a contaminated signal |
US8467821B1 (en) * | 2000-08-16 | 2013-06-18 | International Business Machines Corporation | System and method for anticipating transmit power requirements in wireless mobile units communicating with a base station |
US6745044B1 (en) * | 2000-09-29 | 2004-06-01 | Qualcomm Incorporated | Method and apparatus for determining available transmit power in a wireless communication system |
US8199696B2 (en) | 2001-03-29 | 2012-06-12 | Qualcomm Incorporated | Method and apparatus for power control in a wireless communication system |
US20040185786A1 (en) * | 2001-04-25 | 2004-09-23 | Ramin Mirbaha | Quality of service state predictor for and advanced mobile devices |
WO2002089513A1 (en) * | 2001-04-25 | 2002-11-07 | Fg Microtec Gmbh | Quality of service state predictor for advanced mobile devices |
US8275324B2 (en) * | 2001-11-02 | 2012-09-25 | Qualcomm Incorporated | Method and apparatus for predicting received signal strength in a communication system |
US6932569B2 (en) * | 2002-05-17 | 2005-08-23 | Sikorsky Aircraft Corporation | Active control of multi-element rotor blade airfoils |
US7453861B2 (en) * | 2002-08-02 | 2008-11-18 | At&T Corp | System and method for estimating interference in a packet-based wireless network |
EP1568185B1 (en) | 2002-12-04 | 2011-05-11 | Interdigital Technology Corporation | Reliability detection of channel quality indicator (cqi) and application to outer loop power control |
US8064911B2 (en) * | 2005-12-10 | 2011-11-22 | Electronics And Telecommunications Research Institute | Method of vertical handoff |
US7778657B2 (en) * | 2006-03-28 | 2010-08-17 | Intel Corporation | Method and apparatus to perform power control in a wireless network |
US20070298811A1 (en) * | 2006-06-21 | 2007-12-27 | Lockheed Martin Corporation | System for predicting bandwidth capacity |
US8718567B2 (en) * | 2010-03-25 | 2014-05-06 | Apple Inc. | Methods for calibrating radio-frequency receivers using code division multiple access test equipment |
US11039364B2 (en) * | 2018-09-28 | 2021-06-15 | Google Llc | Methods and apparatus for proactively switching between available networks |
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EP0616435B1 (en) * | 1993-03-19 | 1999-05-26 | Siemens Aktiengesellschaft | Method for transmitter power control of a mobile in a cellular mobile radio network |
-
1994
- 1994-03-17 FI FI941268A patent/FI941268A/en unknown
-
1995
- 1995-03-16 JP JP7523865A patent/JPH09510335A/en active Pending
- 1995-03-16 EP EP95912271A patent/EP0750824B1/en not_active Expired - Lifetime
- 1995-03-16 WO PCT/FI1995/000141 patent/WO1995025365A2/en active IP Right Grant
- 1995-03-16 AT AT95912271T patent/ATE208983T1/en active
- 1995-03-16 DE DE69523902T patent/DE69523902T2/en not_active Expired - Fee Related
- 1995-03-16 AU AU19519/95A patent/AU686346B2/en not_active Ceased
- 1995-03-16 US US08/549,804 patent/US5845208A/en not_active Expired - Fee Related
- 1995-03-16 CN CN95190317A patent/CN1080957C/en not_active Expired - Fee Related
- 1995-11-16 NO NO954640A patent/NO954640L/en unknown
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WO1991017608A1 (en) * | 1990-05-03 | 1991-11-14 | Telefonaktiebolaget Lm Ericsson | A method of predicting future measuring values of handoff decisions |
EP0462952A1 (en) * | 1990-06-21 | 1991-12-27 | Telefonaktiebolaget L M Ericsson | A method for regulating power in a digital mobile telephony system |
WO1994028661A1 (en) * | 1993-05-20 | 1994-12-08 | Telefonaktiebolaget Lm Ericsson | An improved low complexity model based channel estimation algorithm for fading channels |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19535021A1 (en) * | 1995-09-21 | 1997-07-10 | Joerg Dr Arnold | Mobile digital radio signal transceiver |
FR2749994A1 (en) * | 1996-06-18 | 1997-12-19 | Dalsace Eric | Child surveillance system for use by adult in charge of child |
US6026081A (en) * | 1996-07-05 | 2000-02-15 | Nec Corporation | Method of controlling power on forward link in a cellular |
FR2772540A1 (en) * | 1997-12-16 | 1999-06-18 | Sagem | METHOD FOR OPERATING A MOBILE TELEPHONE OF A RADIO COMMUNICATION NETWORK IN ASSOCIATION WITH A TELEPHONE CONNECTED BY WIRE TO THE TELEPHONE NETWORK, AND INTEGRATED SET OF SUCH NETWORKS |
WO1999031905A1 (en) * | 1997-12-16 | 1999-06-24 | Sagem S.A. | Method and system for operating a radio communication network combining a wireless telephone with the telephone network |
WO2001049053A1 (en) * | 1999-12-28 | 2001-07-05 | Matsushita Electric Industrial Co., Ltd. | Base station device and transmission power control method |
EP2237469A1 (en) | 2009-04-03 | 2010-10-06 | TELEFONAKTIEBOLAGET LM ERICSSON (publ) | Method and device for measuring a received signal power in a mobile communication system |
WO2010112398A1 (en) * | 2009-04-03 | 2010-10-07 | Telefonaktiebolaget L M Ericsson (Publ) | Method and device for measuring a received signal power in a mobile comunication system |
US8687599B2 (en) | 2009-04-03 | 2014-04-01 | Telefonaktiebolaget L M Ericsson (Publ) | Method and device for measuring a received signal power in a mobile communication system |
Also Published As
Publication number | Publication date |
---|---|
AU1951995A (en) | 1995-10-03 |
JPH09510335A (en) | 1997-10-14 |
EP0750824A1 (en) | 1997-01-02 |
CN1127052A (en) | 1996-07-17 |
FI941268A0 (en) | 1994-03-17 |
DE69523902T2 (en) | 2002-07-04 |
DE69523902D1 (en) | 2001-12-20 |
US5845208A (en) | 1998-12-01 |
NO954640L (en) | 1996-01-16 |
CN1080957C (en) | 2002-03-13 |
NO954640D0 (en) | 1995-11-16 |
FI941268A (en) | 1995-09-18 |
ATE208983T1 (en) | 2001-11-15 |
AU686346B2 (en) | 1998-02-05 |
WO1995025365A3 (en) | 1995-11-16 |
EP0750824B1 (en) | 2001-11-14 |
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