WO1998052288A1 - Procede et appareil d'evaluation de la capacite d'un systeme de telecommunications - Google Patents

Procede et appareil d'evaluation de la capacite d'un systeme de telecommunications Download PDF

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Publication number
WO1998052288A1
WO1998052288A1 PCT/US1998/002136 US9802136W WO9852288A1 WO 1998052288 A1 WO1998052288 A1 WO 1998052288A1 US 9802136 W US9802136 W US 9802136W WO 9852288 A1 WO9852288 A1 WO 9852288A1
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WO
WIPO (PCT)
Prior art keywords
parameter
load detection
detection parameter
communication
capacity
Prior art date
Application number
PCT/US1998/002136
Other languages
English (en)
Inventor
Philip J. Fleming
Dennis R. Schaeffer
Hua Xu
Original Assignee
Motorola Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Motorola Inc. filed Critical Motorola Inc.
Publication of WO1998052288A1 publication Critical patent/WO1998052288A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements

Definitions

  • the present invention relates generally to communication systems and, more particularly, to determining capacity overload in such communication systems.
  • system planning capability is critical to proper operation of an installed system.
  • operators of such cellular radiotelephone systems need a way to forecast, inter alia, radio frequency (RF) capacity needs and equipment needs so that they can plan well in advance the introduction of capacity enhancing features such as new cell sites, sectorization of existing omni sites, micro-cells and additional RF carriers.
  • RF radio frequency
  • the difficulty in providing useful tools to the operators to make this forecast lies inherently in the difficulty of characterizing the existing cellular radiotelephone system for parameters such as voice quality of a user versus the impact all users have on the capacity of the system.
  • FIG. 1 generally depicts a block diagram of a communication system which may beneficially implement the noise suppression system in accordance with the invention.
  • FIG. 2 generally depicts the steps performed in the preferred embodiment to determine capacity overload in accordance with the invention.
  • FIG. 3 generally depicts how the parameter indicative of call quality is determined in accordance with the invention.
  • FIG. 4 generally depicts how the load detection parameter is determined in accordance with the invention.
  • FIG. 5 generally depicts how the load detection parameter is implemented in accordance with the invention.
  • FIG. 6 generally depicts the normalized forward link call quality parameter (NFLCQP) versus frame error rate (FER) characterization in accordance with the invention.
  • NFLCQP normalized forward link call quality parameter
  • FER frame error rate
  • FIG. 7 generally depicts the normalized reverse link call quality parameter (NRLCQP) versus frame error rate (FER) characterization in accordance with the invention.
  • NRLCQP normalized reverse link call quality parameter
  • FER frame error rate
  • FIG. 8 generally depicts the load detection parameter versus the usage of Erlangs in accordance with the invention.
  • a communication system implements improved capacity estimation.
  • the system determines a call quality parameter related to communication resources in use within the communication system, then determines a load detection parameter which provides information regarding the amount of time a normalized call quality parameter was above a link threshold.
  • the system compares the load detection parameter with information related to system capacity to characterize the system and estimate the capacity of the system.
  • the communication system is a code-division multiple access (CDMA) communication system.
  • the load detection parameter is related to a frame error rate parameter correlated to the coverage area, and more specifically is the frame error rate parameter correlated to the coverage area normalized by the time the communication resource is in use.
  • the load detection parameter is determined for both a reverse link and a forward link of the communication resource to produce a corresponding reverse link detection parameter and a forward link detection parameter.
  • the load detection parameter includes information related to a time in which the load detection parameter is above a predetermined threshold during an observation time period, which is itself variable.
  • the parameter indicative of call quality for a plurality of the communication resources is determined over a predetermined period of time.
  • FIG. 1 generally depicts a block diagram of a communication system 100 which may beneficially implement the techniques described herein related to capacity overload determination in accordance with the invention.
  • the communication system is a code division multiple access (CDMA) cellular radiotelephone system.
  • CDMA code division multiple access
  • the techniques described herein in accordance with the invention can be implemented in any communication system which would benefit from the system. Such systems include, but are not limited to, voice mail systems, cellular radiotelephone systems, trunked communication systems, airline communication systems, etc.
  • a BTS 101-103 is coupled to a CBSC 104.
  • Each BTS 101-103 provides radio frequency (RF) communication to an MS 105.
  • RF radio frequency
  • the transmitter /receiver (transceiver) hardware implemented in the BTSs 101-103 and the MSs 105 to support the RF communication is defined in the document titled TIA/EIA/IS-95A, Mobile Station-Base Station Compatibility Standard for Dual Mode Wideband Spread Spectrum Cellular System, March 1995 available from the Telecommunication Industry Association (TIA).
  • the CBSC 104 is responsible for, inter alia, call processing and mobility management via the MM 109. Other tasks of the CBSC 104 include feature control and transmission/networking interfacing.
  • United States Patent No. 5,475,686 to Bach et al. assigned to the assignee of the present application, and incorporated herein by reference.
  • the OMCR 112 coupled to the MM 109 of the CBSC 104.
  • the OMCR 112 is responsible for the operations and general maintenance of the radio portion (CBSC 104 and BTS 101-103 combination) of the communication system 100.
  • the CBSC 104 is coupled to an MSC 115 which provides switching capability between the PSTN 120 and the CBSC 104.
  • the OMCS 124 is responsible for the operations and general maintenance of the switching portion (MSC 115) of the communication system 100.
  • the HLR 116 and VLR 117 provide the communication system 100 with user information primarily used for billing purposes.
  • the functionality of the CBSC 104, MSC 115, HLR 116 and VLR 117 is shown in FIG. 1 as distributed, however one of ordinary skill in the art will appreciate that the functionality could likewise be centralized into a single element.
  • the CBSC 104 performs signal compression as is well known in the art.
  • the link 126 coupling the MSC 115 with the CBSC 104 is a Tl/El link which is also well known in the art.
  • the compressed signal is transferred to a particular BTS 101-103 for transmission to the MS 105.
  • the compressed signal transferred to a particular BTS 101-103 undergoes further processing at the BTS 101-103 before transmission occurs.
  • the eventual signal transmitted to the MS 105 is different in form but the same in substance as the compressed signal exiting the CBSC 104.
  • the MS 105 When the MS 105 receives the signal transmitted by a BTS 101-103, the MS 105 will essentially "undo" (commonly referred to as "decode") all of the processing done at the BTS 101-103 and the compression performed by the CBSC 104.
  • the MS 105 transmits a signal back to a BTS 101-103, the MS 105 likewise implements compression. After a signal having undergone compression is transmitted by the MS 105 (the MS also performs further processing of the signal to change the form, but not the substance, of the signal) to a BTS 101-103, the BTS 101-103 will "undo" the processing performed on the signal and transfer the resulting signal to the CBSC 104 for speech decoding. After speech decoding by the CBSC 104, the signal is transferred to an end user via the Tl /El link 126.
  • FIG. 2 generally depicts the steps performed in the preferred embodiment to determine capacity overload in accordance with the invention.
  • the process of FIG. 2 is performed in the OMCR 112, however one skilled in the art will realize that the process could equally be performed at the CBSC 104 or even the BTS 101-103.
  • a parameter indicative of call quality is determined at step 203 and the corresponding call quality parameter produced at step 203 is correlated to a particular coverage area to produce a load detection parameter at step 206.
  • the load detection parameter is compared with system capacity information at step 209 and, based on the comparison, an estimate of capacity of the communication system is determined.
  • a test is performed at 303 to determine whether the parameter is related to the forward link or the reverse link of the communication resource.
  • the communication resource is a full duplex communication resource, meaning that the forward link and the reverse link are separated by one another in frequency.
  • the test at step 303 yields that the parameter is for the forward link, the parameter is so determined when three power measurement report messages (PMRM) are received by a base- station within a ten second window as shown at step 306.
  • PMRM power measurement report messages
  • the parameter is determined when 14 frame errors occur within a span of 128 frames as shown at step 309.
  • the value of 14 frame errors out of a span of 128 frames is calibrated to yield a frame error rate (FER) of approximately 1%.
  • FER frame error rate
  • the parameter indicative of call quality exiting steps 306 and/or 309 are input into step 206. While the specific parameters for determining the call quality parameter have been listed in steps 306 and 309 in accordance with the preferred embodiment, one of ordinary skill in the art will appreciate that any number of different parameters could be utilized depending on the parameters readily available in the particular communication system.
  • FIG. 4 generally depicts how the load detection parameter is produced in accordance with the invention.
  • the load detection parameter is computed each time a communication resource (i.e., a call) is released.
  • the load detection parameter could be computed periodically as well.
  • the call quality parameter obtained from step 203 is, in effect, assigned to a particular coverage area within the communication system at step 403. In the preferred embodiment, the assignment is based on the last cell/sector that the MS 105-106 was in.
  • step 406 the release time within a window of a minute of the MS 105-106 is recorded.
  • the call quality parameters for each communication within the coverage area are next summed at step 409, and the sum is then normalized at step 412 by the sum of the times the particular communication resources were in use during the minute window to determine a load detection parameter.
  • the load detection parameter is a measure, in seconds, of how long the load detection parameter was above a predetermined threshold during an observation period as shown in FIG. 8. In the preferred embodiment the observation period is variable and can range anywhere from one minute to a full day.
  • the load detection parameter is incremented at step 415 if the parameter is above a link threshold. In the preferred embodiment, the threshold is 1 for the forward link and 4 for the reverse link.
  • the normalized call quality parameters are both a normalized forward link call quality parameter (NFLCQP) and a normalized reverse link call quality parameter (NRLCQP) .
  • the NFLCQP and the NRLCQP have the property that they can be accurately correlated to FERs within the communication system. For example, as shown in FIG. 6 and FIG. 7, the NFLCQP and NRLCQP (respectively) are shown to act like flags, moving very quickly from zero to their maximum value as the FER increases from less than 1% to 3%. This property of both the NFLCQP and the NRLCQP makes them early indicators of impending poor voice quality which, as described with reference to the prior art, was previously difficult to detect. As such, the NFLCQP and the NRLCQP are used to characterize the cellular radiotelephone system for parameters such as voice quality of a user versus the impact all users have on the capacity of the system in accordance with the invention.
  • FIG. 5 generally depicts how the load detection parameter is implemented in accordance with the invention.
  • information regarding the cell /sector capacity is next gathered at step 503.
  • the information regarding cell /sector capacity is the number of Erlangs used in the particular cell /sector during the observation period.
  • the load detection parameter is compared with the information related to the cell/ sector capacity and a correlation between the two is computed.
  • the correlation is performed using well known linear regression techniques, the result of which is shown in FIG. 8 where the load detection parameter is compared versus the usage of Erlangs.
  • the threshold 803 is chosen to be 10% of the total number of seconds that the load detection parameter could be above the link threshold for an observation period of one hour.
  • a test is performed at step 509 to determine if the correlation is greater than a predetermined correlation.
  • a correlation of .6 or better is used to infer that the high number of events is due to the number of users (i.e., capacity) of the communication system, but any correlation suitable to the situation may be used.
  • the result of the test at step 509 is negative, then the coverage area is not capacity-limited and is thus experiencing problems due to something other than the total number of users on the system.
  • Some typical "other" problems that the coverage area may be experiencing can be interference presented by mobile stations within the coverage area, interference presented by other mobile stations outside of the coverage area, poor radio frequency (RF) received signal strength indications (RSSIs) from desired mobiles within the coverage area, etc.
  • RF radio frequency
  • step 509 If, however, the test at step 509 is positive, then another test is performed at step 515 to determine if the load detection parameter is greater than a predetermined threshold 803. If the result of this test is negative, then the coverage area is capacity limited but not fully loaded. As such, the process flows to step 518 where the percentage of system loading is computed and the maximum capacity is then forecasted. The maximum capacity is forecasted by determining the number of Erlangs in use when the linear regression 806 crosses the predetermined threshold 803. As shown in FIG. 8, this value would be approximately 16 Erlangs. If the result of the test at step 515 is positive, the coverage area capacity-limited and is deemed to be at full capacity at step 521.
  • the communication system can be characterized with respect to system loading.
  • the method described herein is primarily beneficial to indicate to an operator that the coverage area is experiencing problems on either the forward link or the reverse link, and the problem is correlated with system load.
  • an operator might perform coverage area splitting, pilot signal power adjustment, addition of an extra RF channel, etc. to alleviate the problem.
  • the communication system can be arranged to block incoming calls if the condition at step 521 occurs.
  • the coverage area is at full capacity and cannot sustain or support communications with any more mobile stations which desire a communication resource.
  • the CBSC 104 or the BTS 101-103 can be arranged to disallow (commonly referred to in the art as "block") any new MSs which request access to a communication resource within the particular coverage area which is at full capacity as determined at step 521.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention porte sur un système de télécommunications (100) offrant une capacité améliorée d'évaluation de sa propre capacité. Ledit système (100) détermine un paramètre de qualité d'appel (203) relatifs à ses (100) propres ressources en matière de télécommunications, puis détermine un paramètre de détection de charge (206) fournissant des informations sur le temps où un paramètre normalisé de qualité d'appel dépasse le seuil d'une liaison. Pour évaluer sa propre capacité, le système (100) compare (209) le paramètre de détection de charge avec des informations sur sa propre capacité, ce qui permet de caractériser le système (100) et d'en évaluer la capacité (100).
PCT/US1998/002136 1997-05-16 1998-02-06 Procede et appareil d'evaluation de la capacite d'un systeme de telecommunications WO1998052288A1 (fr)

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US85740897A 1997-05-16 1997-05-16
US08/857,408 1997-05-16

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000036863A1 (fr) * 1998-12-17 2000-06-22 Cisco Systems, Inc. Procede et systeme d'allocation de largeur de bande dans un reseau de communications sans fil
GB2347317A (en) * 1999-02-25 2000-08-30 Motorola Ltd Determining a cost function from the actual resource impact of supporting a subscriber in a communications system
EP1061757A2 (fr) * 1999-06-15 2000-12-20 Lucent Technologies Inc. Procédé et appareil pour la détection d'une réduction de capacité d'un système AMRC
US6522628B1 (en) 1999-03-01 2003-02-18 Cisco Technology, Inc. Method and system for managing transmission resources in a wireless communication network
EP1335505A1 (fr) * 2000-10-19 2003-08-13 Huawei Technologies Co., Ltd. Dispositif et procede permettant de realiser le pronostic et le controle de charge multiservice
US6697378B1 (en) 1998-10-16 2004-02-24 Cisco Technology, Inc. Method and apparatus for class based transmission control of data connections based on real-time external feedback estimates obtained using messaging from a wireless network
US6865185B1 (en) 2000-02-25 2005-03-08 Cisco Technology, Inc. Method and system for queuing traffic in a wireless communications network
US6904286B1 (en) 2001-07-18 2005-06-07 Cisco Technology, Inc. Method and system of integrated rate control for a traffic flow across wireline and wireless networks
US6907243B1 (en) 1999-06-09 2005-06-14 Cisco Technology, Inc. Method and system for dynamic soft handoff resource allocation in a wireless network
US7031266B1 (en) 2000-02-25 2006-04-18 Cisco Technology, Inc. Method and system for configuring wireless routers and networks
US7068624B1 (en) 2000-02-25 2006-06-27 Cisco Technology, Inc. Wireless router and method for processing traffic in a wireless communications network

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US4670899A (en) * 1985-05-31 1987-06-02 Northern Telecom Limited Load balancing for cellular radiotelephone system
US5239640A (en) * 1991-02-01 1993-08-24 International Business Machines Corporation Data storage system and method including data and checksum write staging storage
US5448754A (en) * 1993-05-07 1995-09-05 Corporate Technology Partners Radio frequency sharing personal communications system
US5448621A (en) * 1993-08-02 1995-09-05 Motorola, Inc. Dynamic reallocation of spectral capacity in cellular communication systems

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US4670899A (en) * 1985-05-31 1987-06-02 Northern Telecom Limited Load balancing for cellular radiotelephone system
US5239640A (en) * 1991-02-01 1993-08-24 International Business Machines Corporation Data storage system and method including data and checksum write staging storage
US5448754A (en) * 1993-05-07 1995-09-05 Corporate Technology Partners Radio frequency sharing personal communications system
US5448621A (en) * 1993-08-02 1995-09-05 Motorola, Inc. Dynamic reallocation of spectral capacity in cellular communication systems

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6697378B1 (en) 1998-10-16 2004-02-24 Cisco Technology, Inc. Method and apparatus for class based transmission control of data connections based on real-time external feedback estimates obtained using messaging from a wireless network
WO2000036863A1 (fr) * 1998-12-17 2000-06-22 Cisco Systems, Inc. Procede et systeme d'allocation de largeur de bande dans un reseau de communications sans fil
GB2347317A (en) * 1999-02-25 2000-08-30 Motorola Ltd Determining a cost function from the actual resource impact of supporting a subscriber in a communications system
US6522628B1 (en) 1999-03-01 2003-02-18 Cisco Technology, Inc. Method and system for managing transmission resources in a wireless communication network
US7126913B1 (en) 1999-03-01 2006-10-24 Cisco Technology, Inc. Method and system for managing transmission resources in a wireless communications network
US6907243B1 (en) 1999-06-09 2005-06-14 Cisco Technology, Inc. Method and system for dynamic soft handoff resource allocation in a wireless network
US7346354B2 (en) 1999-06-09 2008-03-18 Cisco Technology, Inc. Method and system for dynamic soft handoff resource allocation in a wireless network
EP1061757A2 (fr) * 1999-06-15 2000-12-20 Lucent Technologies Inc. Procédé et appareil pour la détection d'une réduction de capacité d'un système AMRC
EP1061757A3 (fr) * 1999-06-15 2001-06-27 Lucent Technologies Inc. Procédé et appareil pour la détection d'une réduction de capacité d'un système AMRC
US6421529B1 (en) 1999-06-15 2002-07-16 Lucent Technologies Inc. Method and apparatus for the detection of a reduction in capacity of a CDMA system
US6865185B1 (en) 2000-02-25 2005-03-08 Cisco Technology, Inc. Method and system for queuing traffic in a wireless communications network
US7031266B1 (en) 2000-02-25 2006-04-18 Cisco Technology, Inc. Method and system for configuring wireless routers and networks
US7068624B1 (en) 2000-02-25 2006-06-27 Cisco Technology, Inc. Wireless router and method for processing traffic in a wireless communications network
US7826463B2 (en) 2000-02-25 2010-11-02 Cisco Technology, Inc. Method and system for configuring wireless routers and networks
US8958428B2 (en) 2000-02-25 2015-02-17 Cisco Technology, Inc. Method and system for configuring wireless routers and networks
EP1335505A4 (fr) * 2000-10-19 2007-09-26 Huawei Tech Co Ltd Dispositif et procede permettant de realiser le pronostic et le controle de charge multiservice
EP1335505A1 (fr) * 2000-10-19 2003-08-13 Huawei Technologies Co., Ltd. Dispositif et procede permettant de realiser le pronostic et le controle de charge multiservice
EP2757713A1 (fr) * 2000-10-19 2014-07-23 Huawei Technologies Co., Ltd. Dispositif et procédé permettant de réaliser le pronostic et le contrôle de charge multiservice
US6904286B1 (en) 2001-07-18 2005-06-07 Cisco Technology, Inc. Method and system of integrated rate control for a traffic flow across wireline and wireless networks

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