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WO2003019963A1 - Radiotelephone et procede d'exploitation d'un radiotelephone - Google Patents

Radiotelephone et procede d'exploitation d'un radiotelephone Download PDF

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Publication number
WO2003019963A1
WO2003019963A1 PCT/GB2002/003829 GB0203829W WO03019963A1 WO 2003019963 A1 WO2003019963 A1 WO 2003019963A1 GB 0203829 W GB0203829 W GB 0203829W WO 03019963 A1 WO03019963 A1 WO 03019963A1
Authority
WO
WIPO (PCT)
Prior art keywords
radiotelephone
information
signals
volatile memory
transmitter
Prior art date
Application number
PCT/GB2002/003829
Other languages
English (en)
Inventor
Gerald Williams
Diego Giancola
Andrew James Papageorgiou
Jonathan Lucas
Original Assignee
Ubinetics Limited
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 Ubinetics Limited filed Critical Ubinetics Limited
Publication of WO2003019963A1 publication Critical patent/WO2003019963A1/fr

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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • This invention relates to a radiotelephone, and to a method of operating a radiotelephone.
  • the proposed universal mobile telephone system will use the code division multiple access (CDMA) communication technique.
  • Each base station, or node B as it is known in UMTS will modulate signals it transmits with a scrambling code not used by other node Bs in its geographical vicinity.
  • the nature of the signals which will be transmitted by node Bs is such that radiotelephones, or user equipment (UEs) as they are called in UMTS, are such that significant amounts of time and processing resources are required to determine the slot and frame timing and scrambling code information needed to classify signals from a node B. Classification of signals is necessary before useful data can be decoded from that node B.
  • a radiotelephone comprising a processor and a non-volatile memory, the processor being arranged to write to the non-volatile memory information concerning at least one transmitter station with which the radiotelephone has communicated.
  • a method of operating a radiotelephone comprising writing to a non-volatile memory information concerning at least one transmitter station with which the radiotelephone has communicated.
  • the amount of time and the amount of processing resources required, for example on power-up or following an occasion on which no signals were classified, to classify signals transmitted by a node B may be substantially reduced in certain circumstances.
  • a radiotelephone 10 comprises a microprocessor 11, which is connected to receive input from a keypad 12 and has two-way connections to each of a random access memory (RAM) 13 and a non- volatile memory 14, such as electrically programmable read only memory (EPROM) or subscriber identity module (SIM).
  • RAM random access memory
  • non- volatile memory 14 such as electrically programmable read only memory (EPROM) or subscriber identity module (SIM).
  • EPROM electrically programmable read only memory
  • SIM subscriber identity module
  • the non- volatile memory 14 is used to store information such as the identity number of the radiotelephone 10, as well as instructions used to program the processor 11 to operate the radiotelephone 10. These instructions may instead be stored in a separate ROM (not shown).
  • the RAM 13 is used by the processor 11 to process the instructions stored in the non- olatile memory 14, and to temporarily store data during operation of the radiotelephone 10. Data stored in the RAM 13 is lost when the radiotelephone 10 is switched off, but the data stored in the non- volatile memory 14
  • the radiotelephone 10 is a UE configured to operate in a UMTS system.
  • the non- volatile memory 14 or the ROM (not shown) then also includes data representing 512 scrambling codes, any of which could be used by node Bs 15 from which signals could be transmitted to the UE.
  • the UE 10 searches for signals transmitted by node Bs (not shown) and classifies the strongest of these by determining the slot and frame timing and scrambling code information.
  • the UE 10 then begins to demodulate data transmitted by one of the node Bs, and determines the identity of that node B from the data.
  • a Node B 15 together with the area covered by it is often referred to as a cell. Node B and cell are used interchangeably in the following description.
  • the UE 10 maintains, as a background task, a list of cells, each of which is classified as one of the following sets of cells:- a camped cell, which is the cell with which the UE is primarily communicating; a set of active cells, which are cells with which the UE is communicating in a secondary manner, for example in soft handover situation; a set of monitored cells, which are cells mentioned in a neighbouring cell list transmitted by Node Bs over a broadcast channel; and a set of detected cells, which are cells that the UE has classified and is observing but with which the UE is not cornmunicating and which are not in any other set of cells.
  • the list includes, for each cell, the identity of the node B, the scrambling code used by it, and, if available, the timing of signals transmitted by the node B relative to a reference (such as the timing of the camped cell) and the estimated clock drift of the reference clock of the node B.
  • the UE In response to a request to power-down the UE 10, which may be initiated by a user through the keyboard 12 or by the UE itself (for example because of insufficient battery power), the UE stores certain information in the non- volatile memory 14. This information includes all of the information stored in the list, with the most up-to-date timing and clock drift information which is available, and the time of powering-down of the UE. The time of powering-down is taken from a real-time clock (not shown) included in the UE 10. This clock does not rely on any connection to the network including the node Bs 15.
  • the processor 11 On subsequent powering-up of the UE 10, the processor 11 reads the information stored in the non- volatile memory 14, which constitutes the last known information about the various cells. The UE 10 firstly determines the time passed between power-down and power-up. If this period of time is deemed to be too long for the relative timing information to be of use, the timing information for all of the cells is discarded. What determines a period of time which is too long is a matter specific to the implementation of the invention. In a UMTS system in which clock drift rate of clocks in node Bs is determined with reference to, and is assumed to be within 0.01 microseconds in one second of, time as used by satellites of the global positioning system (GPS), the threshold may be 8400 minutes, which is approximately six days.
  • GPS global positioning system
  • the UE 10 typically then determines the slot timing characteristics of significant rays received by it using the primary synchronisation channel (PSCH). This is carried out for the sixteen strongest rays received. The UE 10 then attempts to determine the cell from which the strongest ray originates. This involves extracting the fifteen slot long secondary synchronisation channel (SSC) sequence for the ray. The UE 10 then compares the SSC sequence of the received signal to the SSC sequence corresponding to the code group in which the scrambling code used by the camped cell falls. If a strong correlation is detected, the ray is deemed to be part-classified and no further SSC searches are performed for that ray.
  • PSCH primary synchronisation channel
  • the SSC sequence of that ray is then compared to the SSC sequences corresponding to the code groups in which the scrambling codes used by cells in the active set fall. Again, a strong correlation results in the ray being deemed to be part-classified. The same procedure is then carried out using the SSC sequences corresponding to cells in the monitored set and, if no part-classification results, the procedure is subsequently carried out using the SSC sequences corresponding to cells in the detected set.
  • Part-classification provides the UE 10 with frame timing information.
  • the UE 10 To classify a part-classified ray, the UE 10 correlates signals from a common pilot channel (CPICH) with the scrambling code it expects to be used by the cell. Detection of a high degree of correlation results in classification of that cell. A low correlation indicates that a different scrambling code is used by the cell, and no classification occurs. This procedure is hereafter termed a CPICH check. If the first ray to be classified corresponds to a cell which is in the detected set (rather than a higher priority set), it is assumed that the UE has moved a significant distance since it was powered-down. Accordingly, the UE attempts to classify the remaining rays without recourse to the list.
  • CPICH common pilot channel
  • Classification of a ray provides the UE 10 with frame synchronisation information for that cell.
  • the UE 10 uses this information along with any relative timing information and clock drift estimates (calculated using the clock drift information stored in the list and the elapsed time between power-down and power-up) to estimate the frame synchronisation of the other cells in the list.
  • This estimation has a margin of error which may embrace plural slot timings.
  • the next action taken by the UE 10 is to attempt to part-classify the next strongest ray using the list and any frame synchronisation information estimated using the above described procedure. This is effected by correlating the SSC sequence associated with that ray with the SSC sequences associated with the code groups of the cells in the list, with a high degree of correlation resulting in part-classification of that ray. Classification is then attempted using a CPICH check. This procedure is then repeated for the remaining rays, in decreasing order of strength. Rays which remain unclassified are subsequently classified without recourse to the list.
  • the UE 10 is arranged to detect when a predetermined number of rays, for example three rays, are classified as being the camped cell or originating from cells in the monitored or active sets.
  • a predetermined number of rays for example three rays
  • the UE assumes that it is very near to the location in which it was powered-down.
  • rays from sets other than the detected set are deemed classified when they reach the part-classification stage described above; no CPICH checking is performed. This has the advantage of reduced classification time, but this occurs at the expense of an increased chance of false classification.
  • the invention is applicable also to situations when the UE 10 does not power-down, for example when the UE enters a tunnel or similar.
  • the UE 10 can used the list stored in the non- volatile memory 14 to attempt to classify rays that it receives on exiting the tunnel.
  • the invention may also be used where the UE 10 powers-down other than in a controlled manner, for example because its battery (not shown) becomes disconnected.
  • cell classification involves comparing the SSC sequence of a received ray to an expected SSC sequence, this is not necessary.
  • cell classification could instead be carried out using any one of the techniques described in UK Patent Application No. 0108506.7, or any other suitable technique.

Landscapes

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

Abstract

La présente invention concerne un radiotéléphone (10) comprenant un microprocesseur (11), relié à une entrée de réception en provenance d'un clavier numérique (12) et présentant des connexions bidirectionnelles à chacune parmi un mémoire vive (RAM) (13) et une mémoire non volatile (14), telle qu'une mémoire morte programmable électriquement (EPROM) ou un module d'identification d'abonné (SIM). La mémoire non volatile (14) sert à stocker l'information telle que le numéro d'identité du radiotéléphone (10), ainsi que des instructions utilisées pour la programmation du processeur (11) pour le fonctionnement du radiotéléphone (10). La mémoire vive (13) est utilisée par le processeur (11) pour le traitement des instructions stockées dans la mémoire non volatile (14), et pour la mémorisation temporaire de données au cours du fonctionnement du radiotéléphone (10). Les données mémorisées dans la mémoire vive (13) sont perdues lorsque le radiotéléphone est déconnecté, mais pas les données mémorisées dans la mémoire non volatile (14). Le microprocesseur (11) est adapté à l'inscription dans la mémoire non volatile (14) de l'information concernant au moins une station de transmission avec laquelle le radiotéléphone (10) a été en communication.
PCT/GB2002/003829 2001-08-22 2002-08-20 Radiotelephone et procede d'exploitation d'un radiotelephone WO2003019963A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0120435.3 2001-08-22
GB0120435A GB2379134A (en) 2001-08-22 2001-08-22 Storage of base/transmitter station information

Publications (1)

Publication Number Publication Date
WO2003019963A1 true WO2003019963A1 (fr) 2003-03-06

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Application Number Title Priority Date Filing Date
PCT/GB2002/003829 WO2003019963A1 (fr) 2001-08-22 2002-08-20 Radiotelephone et procede d'exploitation d'un radiotelephone

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GB (1) GB2379134A (fr)
WO (1) WO2003019963A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2399985B (en) * 2003-03-25 2005-05-25 Nec Technologies Method of network acquisition and related cellular radio communication device
GB2407003B (en) * 2003-10-10 2006-08-09 Toshiba Res Europ Ltd Wireless access systems
EP2209329B1 (fr) * 2009-01-15 2012-03-14 NTT DoCoMo, Inc. Procédé et appareil de gestion de paramètres d'un dispositif mobile

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5289527A (en) * 1991-09-20 1994-02-22 Qualcomm Incorporated Mobile communications device registration method
GB2321162A (en) * 1997-01-08 1998-07-15 Nec Technologies Dual Mode Mobile Radio Telecommunications Device
WO1999065270A2 (fr) * 1998-06-08 1999-12-16 Ericsson, Inc. Procedes de reduction des temps d'acquisition de voie dans un systeme de communications de radiotelephone et terminaux mobiles associes
EP1081976A2 (fr) * 1999-09-06 2001-03-07 NTT DoCoMo, Inc. Procédé pour gestion de la recherche de cellules voisines, station mobile et système de communication mobile

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5590397A (en) * 1993-12-17 1996-12-31 Nec Corporation Selecting and prioritizing radio telephone systems at radio terminal
JPH09247737A (ja) * 1996-03-05 1997-09-19 Rookasu:Kk 位置情報検出システム
JPH11308663A (ja) * 1998-04-17 1999-11-05 Kyocera Corp 移動体通信端末における基地局選択処理方式

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5289527A (en) * 1991-09-20 1994-02-22 Qualcomm Incorporated Mobile communications device registration method
GB2321162A (en) * 1997-01-08 1998-07-15 Nec Technologies Dual Mode Mobile Radio Telecommunications Device
WO1999065270A2 (fr) * 1998-06-08 1999-12-16 Ericsson, Inc. Procedes de reduction des temps d'acquisition de voie dans un systeme de communications de radiotelephone et terminaux mobiles associes
EP1081976A2 (fr) * 1999-09-06 2001-03-07 NTT DoCoMo, Inc. Procédé pour gestion de la recherche de cellules voisines, station mobile et système de communication mobile

Also Published As

Publication number Publication date
GB0120435D0 (en) 2001-10-17
GB2379134A (en) 2003-02-26

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