[go: up one dir, main page]

WO1998039943A1 - Procede de mesure des densites de trafic - Google Patents

Procede de mesure des densites de trafic Download PDF

Info

Publication number
WO1998039943A1
WO1998039943A1 PCT/FI1998/000150 FI9800150W WO9839943A1 WO 1998039943 A1 WO1998039943 A1 WO 1998039943A1 FI 9800150 W FI9800150 W FI 9800150W WO 9839943 A1 WO9839943 A1 WO 9839943A1
Authority
WO
WIPO (PCT)
Prior art keywords
base transceiver
mobile stations
test
station
transceiver station
Prior art date
Application number
PCT/FI1998/000150
Other languages
English (en)
Finnish (fi)
Inventor
Petri Jolma
Original Assignee
Nokia Telecommunications Oy
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 Nokia Telecommunications Oy filed Critical Nokia Telecommunications Oy
Priority to AU62168/98A priority Critical patent/AU732025B2/en
Priority to EP98904195A priority patent/EP0935897A1/fr
Priority to JP10537036A priority patent/JP2000509947A/ja
Publication of WO1998039943A1 publication Critical patent/WO1998039943A1/fr
Priority to NO984941A priority patent/NO984941L/no

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/18—Network planning tools

Definitions

  • This invention concerns a method of measuring traffic densities in a cellular radio system.
  • FIG. 1 shows the structure of a cellular radio system.
  • the system comprises an MSC (Mobile Services Switching Centre), a BSC (Base Station Controller), a BTS (Base Transceiver Station), an MS (Mobile Station) and an NMS (Network Management System).
  • the network typically comprises several interconnected mobile services switching centres MSC, only one of which is shown in the figure for the sake of clarity.
  • the mobile station system is connected to a fixed telephone network, e.g. a PSTN (Public Switched Telephone Network) or an ISDN (Integrated Services Digital Network), by way of the mobile services switching centre MSC.
  • PSTN Public Switched Telephone Network
  • ISDN Integrated Services Digital Network
  • the network management system NMS is used to collect information on the network state and to manage the operation of network elements, e.g. by changing the network configuration.
  • a system of this type is e.g. the GSM system which is described more extensively in a book by Michel Mouly & Marie-Bernadette Pautet titled "The GSM System for Mobile Communications".
  • the area where radio coverage is desired is divided into cells, each one of which is served by a base transceiver station.
  • the cell size is determined as a compromise between the desired network capacity and the price of the investment. Due to the high cost of base transceiver station investment, designers aim at keeping the number of base transceiver stations as low as possible.
  • the number of channels used in individual cells and this way the capacity of the entire network are limited by interference between connections which are caused to each other by connections working in adjacent cells on the same channel or on an adjacent channel. Of course, mutual interference is higher the more closely to one another the connections are working. Due to interference, a channel can not be used simultaneously in cells which are closer to each other than the so- called reuse distance. In present day practice, channels are typically reused either in every ninth cell or in every 12 th cell.
  • the same channels When using low-power and thus short-range base transceiver stations, the same channels may be used geographically closer to each other than when using base transceiver stations of higher power, whereby a higher total capacity is achieved for the system. It is thus possible to increase network capacity by using base transceiver stations with as short a range as possible and forming small cells. On the other hand, due to the high costs of base transceiver station investments, the number of base transceiver stations must be minimised.
  • the number of channels required in a cell is estimated by taking into account the estimated number of users within the service area of the cell, their expected call activity and the allowed barring.
  • the required number of channels is allocated so that channels allocated from different base transceiver stations will not cause too much interference to one another.
  • FCA Fixed Channel Allocation
  • Other possible allocation methods are e.g. DCA (Dynamic Channel Allocation) and their combination HCA (Hybrid Channel Allocation).
  • DCA Dynamic Channel Allocation
  • HCA Hybrid Channel Allocation
  • a generally used method of increasing capacity is to install a new base transceiver station with lower transmission capacity in the network.
  • its range or cell size is smaller, whereby less users remain to be served by the individual cell, and on the other hand it causes less interference to nearby base transceiver stations, whereby the frequencies used by the base transceiver station may be reused closer to one another. Since the total capacity of the cellular radio network can be increased in this way, the present trend is to go in for ever smaller so-called microcells and picocells. On the other hand, one must know how to locate these smaller cells to optimise efficiency so that they will relieve the load of the original base transceiver station as effectively as possible.
  • FIG. 2 shows a base transceiver station and its service area, where a traffic hot spot occurs.
  • a traffic hot spot occurs.
  • Such traffic hot spots a great part of the total traffic in the cell is in a small part of the cell.
  • Such areas may be e.g. railway stations, street crossings and sport stadiums.
  • the most sensible thing to do is to look for the cell's traffic hot spot or spots and to locate the new base transceiver station to serve such traffic hot spot.
  • the present invention aims at eliminating or at least at reducing this state-of-the-art defect. This objective is achieved with the method defined in the appended independent claims.
  • a test transmitter is located in the network which transmits a signal causing a change of a known type in the signal received by mobile stations.
  • the mobile stations perform measurements of connection quality in their normal manner and send the results of their measurements to the network in their measurement report.
  • By comparing the measurement reports sent by mobile stations to the network with the known test signal it is possible to deduce which mobile stations are within the service area of the test transmitter.
  • a periodically working pulsed carrier wave as test signal, whereby when the pulse is on, a brief but surely noticeable change is obtained in the signal received by the mobile station.
  • interference can be caused for mobile stations located within the service range of the test transmitter, e.g. in every hundredth bit, which will not noticeably impair the call quality noticed by the user, but which will suffice to calculate a quality value determined for the signal received by the mobile station.
  • quality values follow the periodicity of the test signal.
  • Figure 1 shows the known hierarchical structure of a cellular radio network
  • Figure 2 shows a base transceiver station and its service area where a traffic hot spot occurs
  • Figure 3 shows a base transceiver station and its service area where a traffic hot spot occurs and where a test transmitter according to the invention is located;
  • Figure 4a shows an example of a test pulse sent by the test transmitter as a function of time
  • Figure 4b shows a quality measurement report sent by a mobile station in the test transmitter's service area as a function of time
  • Figure 4c shows a quality measurement report sent by a mobile station outside the test transmitter's service area as a function of time.
  • Figure 3 shows a situation where the traffic hot spot of the base transceiver station in Figure 2 is searched with the method according to the invention using a test transmitter.
  • the test transmitter is placed in the assumed traffic hot spot in Figure 3.
  • the test transmitter is intended to send an interference signal the effect of which on the signal received by the mobile stations can be noticed. Based on these observations it is possible to determine whether the mobile station is within the service area of the test transmitter. Measurements are preferably made during the rush hour.
  • the test transmitter is cheap and easy to manufacture.
  • the transmitter need only be able to generate an interference signal of the desired shape and modulated for downlink frequencies, that is, for use from the base transceiver station of the cellular radio network towards the mobile station, such as e.g. the periodic pulse signal according to Figure 4.
  • the transmitter may be entirely independent of the cellular radio network and it may e.g. operate with an in-built battery.
  • the test transmitter is located in the assumed place of a microcell and it is used for sending e.g. a signal according to Figure 4a having 10 microsecond interference pulses with intervals of 3 milliseconds periodically so that the signal is always on for 2 seconds and off for 2 seconds.
  • the pulses interfere with the signal of the base transceiver station and cause an increase in the signal's bit error ratio.
  • the quality of the signal received by telephones in the transmitter's coverage area is a little poorer when the signal is on than when the signal is off.
  • the pulse ratio is quite low, the interference will not cause any excessive attenuation in the signal received by the mobile stations.
  • Channel coding Due to the channel coding used on the radio channel, the mobile station user will probably not even notice the impairment in quality caused by the test signal, although the impairment from the quality measured by the mobile station is noticeable.
  • Channel coding will be described briefly in the following.
  • channel coding is first performed on the data.
  • the purpose of channel coding is on the one hand to make information transfer better tolerate transfer disturbances and on the other hand to detect transfer errors.
  • decoding may be performed e.g. using the known Viterbi decoder.
  • the information to be transferred may be divided roughly into speech and data traffic, each of which is transferred in frame shape. Due to the different nature of speech and data traffic, different coding methods are used with them to achieve the best result possible.
  • block coding is first done on the data frame to be transferred, where check bits are added to the frame for detecting errors.
  • Convolutional coding is done next, where n bit is always described as 2n bit, whereby an error correction possibility is achieved.
  • the frame is also interleaved, which means changing the mutual order of bits. Since errors are typically short bursts of a few bits, interleaving achieves that bit errors occurring in the transfer will not occur in successive bits.
  • the error correction made possible by convolutional coding works best with individual bit errors, so the error correction algorithm is made to work better with the aid of interleaving.
  • the bits of the speech signal coded e.g. in accordance with specification GSM 06.10 are divided according to their importance into three classes, 1a, 1b and 2 respectively.
  • Block coding is first performed on the bits of class 1a which are of major importance to the quality of the transferred speech.
  • Convolutional coding is done on block-coded 1a bits and on non-coded 1b bits and the class 2 bits not coded before interleaving are added to the result of the convolutional coding.
  • bit error ratio can be defined in many different ways. One useable method is to re-code the received and decoded data and to compare the result thus obtained with the original received signal.
  • the mobile station reports the results of its quality measurements to the base transceiver station on an SACCH (Slow Associated Control Channel) for the individual connection. Due to the limitation of the spectrum in use, the bit error ratio is not sent as such over the radio path, but the quality values are divided into eight rougher quality classes in accordance with the appended table.
  • SACCH Slow Associated Control Channel
  • mobile stations located within the service area of the test transmitter detect the decline in bit error ratio of the signal which is caused by the test signal.
  • the magnitude of decline in the bit error ratio can be adjusted e.g. by pulse ratio selection. E.g. by choosing a pulse ratio of 100, interference will be caused only to every hundredth bit and the increase in bit error ratio caused by the test signal will be approximately 0.5 %. It can be seen from the table above that this corresponds with quality class RXQUAL_3. However, even then the decline is so small that the quality of the call will not decline noticeably. Thus, the mobile station user need not necessarily notice the existence of the test signal.
  • the quality value stated by the telephone in its measurement report will drop from the value RXQUALJ) to the value RXQUAL_3.
  • the pulse ratio 300 of our example that is, e.g. a pulse of 10 microseconds at intervals of 3 milliseconds
  • the increase in bit error ratio will be about 0.2 % and the quality class will be RXQUAL_1.
  • the test signal is periodic in accordance with Figure 4a, that is, the pulse signal is on for 2 seconds and off for 2 seconds.
  • the mobile stations within the service area of the test transmitter will notice the decline in quality only when the pulse signal is on.
  • the mobile stations within the service area of the test transmitter always report the value RXQUAL_0 according to Figure 4b for a time of two seconds and the value RXQUAL_1 for the following two seconds.
  • those mobile stations which are not within the service area of the test transmitter will not receive any periodic interference from the test transmitter's signal, but they will report uniform quality values in accordance with Figure 4c.
  • the mobile stations send their measurement results to the network normally in accordance with specification GSM 04.08.
  • the network uses the received measurement reports for controlling the transmission power and for making any decisions to change channel, which functions are typically located in base station controller BSC.
  • these entirely normal quality reports are also examined for such dependencies on the test signal, on the basis of which it is established whether the mobile station is within the service area of the test transmitter.
  • studying quality measurement results obtained from measurement reports sent by mobile stations on the SACCH channel it is found that the quality report of some mobile stations are always periodically at value 0 for 2 seconds and at value 1 for 2 seconds in accordance with Figure 4b.
  • the method does not give any direct information on the geographical area of a traffic concentration, but such information on the number of mobile stations located within the transmitter's service area which takes drop-out and other characteristics of the radio channel into account. Under these circumstances, measurement information is obtained on the number of mobile stations directly serviceable by the base transceiver station, if the aerial of the base transceiver station is located in the test transmitter's place.
  • An examination of dependencies of measurement results on the test signal can be done e.g. through software in that network element which processes the measurement report even otherwise.
  • this element is the base station controller BSC.
  • the function can be performed e.g. with a physical analyser and a connected control computer.
  • Measurement reports are processed for doing power control and channel change decisions for the connection between base transceiver station and mobile station over the radio interface, whereby the units in charge of these functions must in any case study the time series formed by the successive quality reports of the individual mobile station. Under these circumstances, such a function may be added directly to the said units which is used for determining the dependence of quality reports on the test signal.
  • the physical analyser could be e.g. a device monitoring the so- called A-bis interface between base transceiver station and base station controller (see Figure 1) and storing quality reports of different mobile stations which it picks up from the interface.
  • the device could be located directly to monitor traffic at the air interface and to pick up quality reports of individual mobile stations directly from this interface.
  • the service area of a transmitter or base transceiver station is the area wherein the mobile station can detect the transmitter signal. This signal causes interference to another signal transferred at the same frequency, although it is not necessarily more powerful than the said other signal.
  • the service areas of adjacent base transceiver stations are always slightly overlapping.
  • the base transceiver station's dominance area again is the area wherein the base transceiver station's signal is most powerful. Mobile stations always seek connection with that base transceiver station in the dominance area of which they are located. Unlike the service areas, the dominance areas of adjacent base transceiver stations are not overlapping.
  • the test signal can be chosen to have a band corresponding to a traffic frequency used in operation. If frequency jumping is used in the network, it is preferable to use a test signal having so wide a band that it will cover the whole frequency area used for frequency jumping in the cell in question.
  • the test signal may cause interference also to other such equipment than mobile stations which is sensitive to radio power. These effects can be minimised e.g. with a correct choice of pulse ratio and ON periods.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Monitoring And Testing Of Transmission In General (AREA)
  • Traffic Control Systems (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

Lorsque l'on augmente la capacité d'un réseau radio cellulaire, on installe souvent une seconde station de base émettrice/réceptrice de moindre puissance, dans la cellule originale, afin de desservir des points chauds de trafic de la cellule originale. Le résultat final dépend en grande partie de la bonne définition de l'emplacement du point chaud de trafic et du nombre de stations mobiles. Dans l'invention, on mesure l'emplacement des points chauds et le nombre des stations mobiles, en plaçant un émetteur témoin dans la cellule, lequel va provoquer le brouillage du signal reçu par les stations mobiles. Tout changement provoqué par le brouillage peut être détecté dans la signalisation de qualité des stations mobiles
PCT/FI1998/000150 1997-02-24 1998-02-19 Procede de mesure des densites de trafic WO1998039943A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
AU62168/98A AU732025B2 (en) 1997-02-24 1998-02-19 Method of measuring traffic densities
EP98904195A EP0935897A1 (fr) 1997-02-24 1998-02-19 Procede de mesure des densites de trafic
JP10537036A JP2000509947A (ja) 1997-02-24 1998-02-19 トラフィック密度を測定する方法
NO984941A NO984941L (no) 1997-02-24 1998-10-23 FremgangsmÕte for mÕling av trafikktettheter

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI970760 1997-02-24
FI970760A FI107500B (fi) 1997-02-24 1997-02-24 Liikennetihentymien mittausmenetelmä

Publications (1)

Publication Number Publication Date
WO1998039943A1 true WO1998039943A1 (fr) 1998-09-11

Family

ID=8548265

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1998/000150 WO1998039943A1 (fr) 1997-02-24 1998-02-19 Procede de mesure des densites de trafic

Country Status (7)

Country Link
EP (1) EP0935897A1 (fr)
JP (1) JP2000509947A (fr)
CN (1) CN1217859A (fr)
AU (1) AU732025B2 (fr)
FI (1) FI107500B (fr)
NO (1) NO984941L (fr)
WO (1) WO1998039943A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002003736A1 (fr) * 2000-07-03 2002-01-10 Telefonaktiebolaget Lm Ericsson (Publ) Systeme et procede de mise a l'epreuve d'un systeme de communication

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0431956A2 (fr) * 1989-12-07 1991-06-12 Motorola, Inc. Système de diagnostic pour radiotéléphone cellulaire
EP0568824A2 (fr) * 1992-04-08 1993-11-10 Us West New Vector Group, Inc. Système pour marquer des zônes dans une zône de service cellulaire
WO1994005098A1 (fr) * 1992-08-18 1994-03-03 Televerket Procede d'estimation de la densite du trafic dans les reseaux de telephone mobile
WO1994006222A1 (fr) * 1992-08-28 1994-03-17 Telia Ab Procede et configuration permettant une meilleure planification des cellules dans les reseaux de radiotelecommunications mobiles
WO1996035305A1 (fr) * 1995-05-03 1996-11-07 Telefonaktiebolaget Lm Ericsson (Publ) Emetteur/recepteur de test pour la planification de cellules

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0431956A2 (fr) * 1989-12-07 1991-06-12 Motorola, Inc. Système de diagnostic pour radiotéléphone cellulaire
EP0568824A2 (fr) * 1992-04-08 1993-11-10 Us West New Vector Group, Inc. Système pour marquer des zônes dans une zône de service cellulaire
WO1994005098A1 (fr) * 1992-08-18 1994-03-03 Televerket Procede d'estimation de la densite du trafic dans les reseaux de telephone mobile
WO1994006222A1 (fr) * 1992-08-28 1994-03-17 Telia Ab Procede et configuration permettant une meilleure planification des cellules dans les reseaux de radiotelecommunications mobiles
WO1996035305A1 (fr) * 1995-05-03 1996-11-07 Telefonaktiebolaget Lm Ericsson (Publ) Emetteur/recepteur de test pour la planification de cellules

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002003736A1 (fr) * 2000-07-03 2002-01-10 Telefonaktiebolaget Lm Ericsson (Publ) Systeme et procede de mise a l'epreuve d'un systeme de communication
US6662008B1 (en) 2000-07-03 2003-12-09 Telefonaktiebolaget Lm Ericsson (Publ) System and method for testing a communication system

Also Published As

Publication number Publication date
FI970760A0 (fi) 1997-02-24
AU732025B2 (en) 2001-04-12
FI107500B (fi) 2001-08-15
NO984941D0 (no) 1998-10-23
CN1217859A (zh) 1999-05-26
EP0935897A1 (fr) 1999-08-18
NO984941L (no) 1998-10-23
FI970760L (fi) 1998-08-25
AU6216898A (en) 1998-09-22
JP2000509947A (ja) 2000-08-02

Similar Documents

Publication Publication Date Title
EP0819363B1 (fr) Planification automatique des canaux de commande dans des systemes d'attribution adaptative de canaux
EP1155588B1 (fr) Systeme de radio mobile et procede d'attribution de canaux dans un systeme de radio mobile
US10009134B2 (en) Method and apparatus for scheduling dedicated transmissions in response to interference levels at neighboring base stations
CA2348990C (fr) Utilisation de la localisation de station mobile et de la commande de puissance pour l'optimisation de reseau radio
US7583933B2 (en) Dynamic frequency selection in a wireless communication network
US6418317B1 (en) Method and system for managing frequencies allocated to a base station
JP4695135B2 (ja) 無線資源の動的割当て
AU757145B2 (en) Method and system for radio frequency measurement and automatic frequency planning in a cellular radio system
CA2217288C (fr) Systeme et methode d'affectation dynamique de canaux
EP2215753B1 (fr) Contrôle d'interférences entre systèmes
EP0960545B1 (fr) Procede d'affectation de canal et systeme correspondant
EP2630729B1 (fr) Procédés et appareil pour réseau auto-organisé à coordination de brouillage entre cellules
US6195554B1 (en) Channel assignment based on uplink interference level and channel quality measurements with a forward and backward reassignment step
EP1180881A1 (fr) Procédé et système d'allocation adaptive de transmission de données en utilisant des informations de charge des stations de base voisines
EP0819364B1 (fr) Planification stabilisee de disposition des voies de commande grace a des canaux de trafic reserves a configuration dispersee
FI107667B (fi) Menetelmä palvelutason asettamiseksi digitaalisessa matkaviestinjärjestelmässä ja digitaalinen matkaviestinjärjestelmä
US6240275B1 (en) System and method for channel assignment based upon interference and channel quality measurements
EP1131977A1 (fr) Procede d'attribution des canaux et systeme cellulaire
AU732025B2 (en) Method of measuring traffic densities
WO1998033344A1 (fr) Mesure de l'utilisation de telephones mobiles cellulaires
Ling et al. Capacity of intelligent underlay and overlay network
CA2217192C (fr) Planification stabilisee de disposition des voies de commande grace a des canaux de trafic reserves a configuration dispersee
BASYIGIT Solution of Problems on Bad Signal Quality via RF Optimization in Cellular Network

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 98800176.4

Country of ref document: CN

AK Designated states

Kind code of ref document: A1

Designated state(s): AL AM AT AU AZ BA BB BG BR BY CA CH CN CU CZ DE DK EE ES FI GB GE GH GM GW HU ID IL IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT UA UG US UZ VN YU ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW SD SZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN ML MR NE SN TD TG

WWE Wipo information: entry into national phase

Ref document number: 09176603

Country of ref document: US

WWE Wipo information: entry into national phase

Ref document number: 1998904195

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 62168/98

Country of ref document: AU

121 Ep: the epo has been informed by wipo that ep was designated in this application
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

WWP Wipo information: published in national office

Ref document number: 1998904195

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: CA

WWG Wipo information: grant in national office

Ref document number: 62168/98

Country of ref document: AU

WWW Wipo information: withdrawn in national office

Ref document number: 1998904195

Country of ref document: EP