EP0875118A2 - Procede pour acceder a une microcellule au moyen de voies de commande analogiques - Google Patents

Procede pour acceder a une microcellule au moyen de voies de commande analogiques

Info

Publication number
EP0875118A2
EP0875118A2 EP97947276A EP97947276A EP0875118A2 EP 0875118 A2 EP0875118 A2 EP 0875118A2 EP 97947276 A EP97947276 A EP 97947276A EP 97947276 A EP97947276 A EP 97947276A EP 0875118 A2 EP0875118 A2 EP 0875118A2
Authority
EP
European Patent Office
Prior art keywords
microcell
macrocell
radiotelephone
control channel
signal strength
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP97947276A
Other languages
German (de)
English (en)
Inventor
Donald Hanley
Michael Mccarthy
Earl Christie
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nortel Networks Ltd
Original Assignee
Northern Telecom Ltd
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 Northern Telecom Ltd filed Critical Northern Telecom Ltd
Publication of EP0875118A2 publication Critical patent/EP0875118A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/20—Selecting an access point
    • 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
    • H04W16/24—Cell structures
    • H04W16/28—Cell structures using beam steering
    • 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
    • H04W16/24—Cell structures
    • H04W16/32—Hierarchical cell structures
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria

Definitions

  • the present invention relates to radio communications. More particularly, the present invention relates to cellular radiotelephone systems.
  • a cellular radio communication system is typically comprised of a number of cells covering a geographic region. Each cell is comprised of a base station that is allocated a number of radio channels for transmitting from a number of directional antennas. The cell may also be divided up into sectors, each sector having a number of different channels.
  • the cell shapes are determined by both the radiation pattern of the antennas and the local conditions at the cell site.
  • Cells are typically idealized as hexagonal patterns since such a pattern closely approximates the ideal antenna radiation pattern.
  • FIG. 2 illustrates a prior art cell site connected to the mobile telephone exchange (MTX).
  • the antenna (200) at the cell site is connected to the base station (210) that contains the receivers and transmitters for the cell site to communicate with the mobile radiotelephone (230).
  • the base station is connected to and controlled by a base station controller (BSC) (215).
  • BSC base station controller
  • the BSC (215) is connected to the MTX (220) that is then connected to the public switched telephone network (PSTN).
  • PSTN public switched telephone network
  • the MTX handles all of the switching for a number of cell sites and BSCs, routing calls from the PSTN to the appropriate cell site and routing calls from the cell site to the PSTN.
  • a subscriber is not configured to a specific cell.
  • a radio channel is allocated to the radiotelephone for call initiation based on a number of factors including: the Received Signal Strength Indicator (RSSI) (measured during access), the type of radiotelephone (analog or digital), interference conditions, and the availability of radio channels.
  • RSSI Received Signal Strength Indicator
  • FIG. 3 shows a microcell (300) that is located within the bounds of a macrocell (305).
  • the radius of the macrocell (305) is approximately 500 meters while the radius of a microcell (300) is typically less than 200 meters.
  • Cold spot coverage occurs in a macrocell system that has radio signal coverage holes. In this situation, the radiotelephone either cannot communicate with any base station or the quality of the communication signal is substantially reduced due to lack of coverage.
  • a macrocell or macrocells experience a high concentration of traffic. In this case, the base station may run out of available frequencies and not be able to handle additional radiotelephone traffic.
  • microcells are typically added as underlay cells to the existing macrocell system. Once underlaid, the microcells require a frequency assignment. The typical methods for assigning frequency groups to microcells are reusing frequencies and reserving or segregating frequencies from the macrocell frequency groups.
  • a microcell reuses the frequencies assigned to the macrocell system.
  • the frequency reservation or segregation scheme reserves a block of frequencies normally used by the macrocell system.
  • a microcell handles any traffic within its defined boundaries. This includes calls originating or terminating within its range as well as hand- offs of radiotelephones passing through its coverage area. In reality, however, this operation is difficult to achieve.
  • the present invention encompasses a process for accessing a microcell by a radiotelephone.
  • the microcell is underlaid to a macrocell.
  • the process first determines the proximity of the radiotelephone to the microcell. If the proximity is less than or equal to a predetermined distance, the radiotelephone is assigned to the microcell. If the proximity is greater than a predetermined distance, the radiotelephone is assigned to the overlying macrocell.
  • the proximity of the radiotelephone to the microcell is determined by the microcell using a control channel with the same frequency and digital color code as the macrocell's control channel. This allows the microcell to monitor the RSSI .of the radiotelephone. If the RSSI is above a predetermined threshold, and the microcell has available voice channels, the radiotelephone is assigned to the microcell.
  • FIG. 1 shows a typical prior art cellular system frequency layout.
  • FIG. 2 shows a typical prior art cell site.
  • FIG. 3 shows a macrocell with an underlaid microcell.
  • FIG. 4 shows a flowchart of the process of the present invention.
  • FIG. 5 shows a block diagram of a typical prior art radiotelephone of the present invention.
  • the process of the present invention determines the radiotelephone's proximity to the microcell using the microcell's control channel. If the RSSI of the radiotelephone is greater than or equal to a predetermined threshold and a voice channel is available from the microcell, the radiotelephone is assigned to the microcell.
  • FIG. 5 A typical prior art analog radiotelephone of the present invention is illustrated in FIG. 5.
  • This radiotelephone is comprised of a microphone (510) that takes the voice signal from the user and converts it to an analog signal.
  • the transmitter (520) modulates the voice signal to the proper frequency assigned by the system and transmits it, through the dup lexer (530) to the antenna (535) for radiation to the cell site.
  • the antenna (535) also receives radiotelephone signals from the cell site.
  • the dup lexer couples the antenna (535) to the receiver (525).
  • the receiver (525) then demodulates the received signal into an analog signal for conversion to a sound signal by the speaker (505).
  • the radiotelephone user inputs telephone numbers and generally controls the operation of the radiotelephone through the keypad and display (500). This information is used by the radiotelephone controller (515) to control transmitter (520) and receiver (525) and to determine what telephone number is transmitted.
  • the radiotelephone accesses a cell's control channel when it sends an origination message to a cell or responds to a page from a cell.
  • the cell measures the radiotelephone's RSSI during the access to determine if it is strong enough for communication with that particular cell.
  • Control channels are typically reused within a cellular system requiring that the radiotelephone identify itself with the cell since it cannot be identified on the basis of frequency.
  • the microcell of the present invention uses a receive-only control channel tuned to the same frequency as the overlaid macrocell. If the microcell were allowed to transmit on this frequency, the macrocell coverage area would be subjected to intolerable levels of interference.
  • the microcell also uses the same digital color code (DCC) value as the macrocell.
  • DCC digital color code
  • up to three different DCC's are used to differentiate between reuses of the control channel frequencies. For example, if a radiotelephone accesses a cell having control channel fl and DCCl, then another cell having the same control channel fl but DCC2 will ignore the access. In a typical frequency plan, 21 different control channel frequencies are used.
  • the microcell uses the same control channel and DCC as the overlaid macrocell to monitor the macrocell control channel for access attempts by a radiotelephone.
  • the microcell measures the RSSI of the radiotelephone, thus enabling the BSC to determine whether the access should be served by the macrocell or the microcell.
  • the macrocell and microcell of the present invention are both controlled by the same BSC. This enables the system to better coordinate channel allocations between the two cells, thus minimizing delays and race conditions between cells. Alternate embodiments could be controlled by multiple BSCs.
  • FIG. 4 A flowchart of the process of the present invention is illustrated in FIG. 4.
  • the process begins with the macrocell and microcell monitoring their control channels (401). If an access attempt is detected on either control channel (402), the control channel measures the radiotelephone's signal strength (RSSI m ) during the access (403) and reports the access to the BSC (405). The BSC then determines if the access was reported by the macrocell or the microcell (440). If the access was reported by the macrocell, the BSC waits for a duplicate access message from the microcell (410). In the preferred embodiment, this message must be received in the range of 20 - 200 ms to be considered a valid message. Alternate embodiments use other time thresholds for determining that a valid access message exists.
  • RSSI m radiotelephone's signal strength
  • the radiotelephone's RSSI as measured by the microcell's control channel (RSSI m ), is compared to a predetermined RSSI threshold (425). If the RSSI m is greater than or equal to the RSSI threshold (425) and the microcell has available voice channels, the radiotelephone is assigned to the microcell (430).
  • This predetermined threshold is determined during RF planning of the cellular system. It is the threshold below which a quality communication cannot take place between the radiotelephone and the microcell.
  • the radiotelephone is assigned to the macrocell (435), assuming the macrocell has available voice channels. If there are no available voice channels, the radiotelephone is not allowed access to the macrocell. If the BSC does not receive a duplicate message, this implies that the radiotelephone is outside the microcell's coverage area and could not be heard by the microcell.
  • the access messa ⁇ re is from the microcell.
  • the BSC waits for 20 - 200 ms for a duplicate message from the macrocell (450). If the duplicate message is received in time (455), then the radiotelephone's RSSI, as measured by the microcell's control channel (RSSI m ) is compared to a predetermined RSSI threshold (460). If the RSSI m is greater than or equal to the RSSI threshold and the microcell has available voice channels, the radiotelephone is assigned to the microcell (430). Otherwise, the radiotelephone is assigned to the macrocell (435), assuming it has available voice channels. If the macrocell does not have voice channels available, the radiotelephone is denied access to the macrocell.
  • RSSI m as measured by the microcell's control channel
  • the access attempt is discarded (470). This may have been caused by a collision on the macrocell control channel due to more than one radiotelephone attempting to access the control channel at the same time. This cannot be detected by the microcell.
  • the goal of the process of the present invention is to use the macrocell control channel to manage the communications between the radiotelephone and the MTX.
  • the microcell's control channel is used to assess the radiotelephone's proximity to the microcell.
  • the radiotelephone is assigned to the microcell only if the access is seen by both the macrocell and the microcell, and the microcell RSSI reading is high enough to indicate that the radiotelephone is within the microcell's coverage area.
  • the microcell's coverage area is 200 meters from the microcell. Alternate embodiments have other coverage areas. The above described embodiment assumes there is only one microcell in a given macrocell. However, alternate embodiments use multiple microcells deployed in a single macrocell's coverage area. With several control channels tuned to the same frequency and DCC, the BSC collects all of the duplicate accesses received within the delay period and determines to which cell the radiotelephone will be assigned.
  • the above described embodiment also assumes that the microcell and the macrocell are controlled by the same BSC. However, alternate embodiments use different BSCs to control the cells. If the radiotelephone is going to be assigned to a microcell, the macrocell BSC requests the microcell BSC to identify the microcell voice channel to be allocated to the radiotelephone.
  • microcell with more than one macrocell.
  • the microcell must be equipped to monitor multiple control channels.
  • the preferred embodiment was discussed using AMPS as an example. It should be clear that the present invention can be used with other cellular systems that use analog access channels.

Landscapes

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

Abstract

Le procédé de la présente invention est conçu pour le contrôle d'une voie de commande de microcellule au moyen d'une microcellule ayant une voie de commande accordée sur la même fréquence et le même code couleur numérique. La microcellule et la macrocellule possèdent toutes deux le même organe de commande qui attend un message d'accès. Une fois que le message d'accès est reçu, l'organe de commande attend un message d'accès réplique pendant un laps de temps préétabli. Si le message d'accès réplique est reçu de la microcellule, l'indicateur d'intensité du signal reçu (RSSI) de la voie de commande de la microcellule du radiotéléphone est mesuré (RSSIm) de façon à ce qu'il soit établi s'il est supérieur ou égal au seuil exigé pour une communication adéquate avec la microcellule. Si le RSSIm est supérieur ou égal à ce seuil, le radiotéléphone est affecté à la microcellule. Sinon, le radiotéléphone est affecté à la macrocellule.
EP97947276A 1996-10-28 1997-10-24 Procede pour acceder a une microcellule au moyen de voies de commande analogiques Withdrawn EP0875118A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US740369 1985-06-03
US74036996A 1996-10-28 1996-10-28
PCT/US1997/019295 WO1998019474A2 (fr) 1996-10-28 1997-10-24 Procede pour acceder a une microcellule au moyen de voies de commande analogiques

Publications (1)

Publication Number Publication Date
EP0875118A2 true EP0875118A2 (fr) 1998-11-04

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Application Number Title Priority Date Filing Date
EP97947276A Withdrawn EP0875118A2 (fr) 1996-10-28 1997-10-24 Procede pour acceder a une microcellule au moyen de voies de commande analogiques

Country Status (4)

Country Link
EP (1) EP0875118A2 (fr)
BR (1) BR9706896A (fr)
CA (1) CA2241363A1 (fr)
WO (1) WO1998019474A2 (fr)

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AU8458298A (en) * 1997-07-11 1999-02-08 Nortel Networks Corporation Method and apparatus for switching between public macrocellular telephone systemand private microcellular telephone system
CN1214661C (zh) * 2002-02-09 2005-08-10 华为技术有限公司 移动通信中业务信道的分配方法
DE602004011758T2 (de) * 2004-06-30 2009-03-26 Koninklijke Kpn N.V. Konzept zur Ermöglichung von Zugriff auf ein Netzwerk unter Nutzung eines lokalen, drahtlosen Netzes
US7978667B2 (en) 2006-11-30 2011-07-12 Kyocera Corporation Management of WLAN and WWAN communication services to a multi-mode wireless communication device
US9532399B2 (en) 2006-11-30 2016-12-27 Kyocera Corporation Apparatus, system and method for managing wireless local area network service to a multi-mode portable communication device
US8102825B2 (en) 2006-11-30 2012-01-24 Kyocera Corporation Detection of a multi-mode portable communication device at a mesh network
US7969930B2 (en) 2006-11-30 2011-06-28 Kyocera Corporation Apparatus, system and method for managing wireless local area network service based on a location of a multi-mode portable communication device
US8103285B2 (en) 2007-04-19 2012-01-24 Kyocera Corporation Apparatus, system and method for determining a geographical location of a portable communication device
US8233433B2 (en) 2008-02-26 2012-07-31 Kyocera Corporation Apparatus, system and method for initiating WLAN service using beacon signals
WO2009108723A2 (fr) * 2008-02-26 2009-09-03 Kyocera Corporation Dispositif, système t procédé de gestion d'un service sans fil vers un dispositif de communication sans fil
FR2938148A1 (fr) * 2008-10-31 2010-05-07 Alcatel Lucent Procede et systeme de localisation de terminaux de communication radio en mode de veille dans un reseau de communication radio cellulaire.
US8165577B2 (en) 2009-03-19 2012-04-24 Kyocera Corporation Pilot signal transmission management

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GB9016277D0 (en) * 1990-07-25 1990-09-12 British Telecomm Location and handover in mobile radio systems
US5357559A (en) * 1991-12-12 1994-10-18 Telefonaktiebolaget L M Ericsson Listening control channel in a cellular mobile radiotelephone system
US5546443A (en) * 1992-10-26 1996-08-13 Ericsson Ge Mobile Communications, Inc. Communication management technique for a radiotelephone system including microcells
US5499386A (en) * 1993-07-09 1996-03-12 Telefonaktiebolaget L M Ericsson Best server selection in layered cellular radio system

Non-Patent Citations (1)

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Title
See references of WO9819474A3 *

Also Published As

Publication number Publication date
WO1998019474A3 (fr) 1998-10-08
WO1998019474A2 (fr) 1998-05-07
CA2241363A1 (fr) 1998-05-07
BR9706896A (pt) 2001-08-28

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