AU692633B2 - Large coverage mobile radio base station - Google Patents
Large coverage mobile radio base station Download PDFInfo
- Publication number
- AU692633B2 AU692633B2 AU40663/95A AU4066395A AU692633B2 AU 692633 B2 AU692633 B2 AU 692633B2 AU 40663/95 A AU40663/95 A AU 40663/95A AU 4066395 A AU4066395 A AU 4066395A AU 692633 B2 AU692633 B2 AU 692633B2
- Authority
- AU
- Australia
- Prior art keywords
- mobile stations
- offset
- base station
- far
- time slots
- 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.)
- Ceased
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Classifications
-
- 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
- H04W16/26—Cell enhancers or enhancement, e.g. for tunnels, building shadow
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
- H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
- H04B7/2662—Arrangements for Wireless System Synchronisation
- H04B7/2671—Arrangements for Wireless Time-Division Multiple Access [TDMA] System Synchronisation
- H04B7/2678—Time synchronisation
- H04B7/2681—Synchronisation of a mobile station with one base station
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W56/00—Synchronisation arrangements
- H04W56/0055—Synchronisation arrangements determining timing error of reception due to propagation delay
- H04W56/0065—Synchronisation arrangements determining timing error of reception due to propagation delay using measurement of signal travel time
- H04W56/007—Open loop measurement
- H04W56/0075—Open loop measurement based on arrival time vs. expected arrival time
-
- 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
- H04W72/04—Wireless resource allocation
- H04W72/044—Wireless resource allocation based on the type of the allocated resource
- H04W72/0446—Resources in time domain, e.g. slots or frames
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/20—Control channels or signalling for resource management
- H04W72/21—Control channels or signalling for resource management in the uplink direction of a wireless link, i.e. towards the network
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
Description
P 00,011 28' 5;91 Regulationi 3.2
AUSTRALIA
Patents Act 1990
ORIGINAL
COM4PLETE SPECIFICATION\ STANDARD PATENT Invention Title: C C
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"LARGE COVERAGE MOBILE RADIO BASE STATION" Tie following statement is a full dlescription of this invention, including the best method of perfoiming it known to LIS:- LI:- 2 This invention relates to cellular radiocommunications systems of the timedivision multiple access (TDMA) type.
The European GSM system is typical of such TDMA systems and the invention will essentially be described within the framework of this system. More information about this system is given in the book "The GSM system", written and published by Michel MOULY and Marie-Bernadette PAUTET, Paris, 1992. The invention is however not limited to this particular system and, as will be understood, can be equally well applied to any TDMA system.
The invention deals with the specific problem of providing satisfactory coverage in vast areas, for instance rural or coastal areas, typically with coverage radii larger than 35 km (this value, which is in no way limiting, being the nominal value of the maximum size of a GSM cell capable of being covered without the need for special protocols).
In what follows, the qualifier "near" will be used to describe mobile stations situated within this nominal cell radius at a distance ranging from 0 to 35 km from the base station) and the qualifier "far" will be used to describe mobile stations situated beyond this limit, i.e. beyond 35 km, typically within a radius ranging from to 70 km.
p A first method for exchanging communications with far mobile stations, which is disclosed on p 347 of the above mentioned book, "The GSM system", consists in .a reserving two time slots (TS, Time-Slot, in GSM terminology) per mobile station instead of one, so as to have a double guard time, sufficient to cover distances between mobile stations and base stations (BTS, Base Transceiver Station, in GSM terminology) that are significantly larger than 35 km.
This technique has the disadvantage of halving the number of mobile stations that may be managed simultaneously, and requires that the position of the networ; access request signal be searched over the duration of two time slots instead of one, thereby increasing the duration of the siep comprising the sampling and the search for the main correlation peak.
Another known technique, consists in using two base stations, onie to cover the 0-35 km area and the other to cover the 35-70 km area. This technique is efficient IP I_ I sl I I- and compensates for the problems of the first technique. However, it requires double the number of transmitters and broadcast channels (BCCH, Broadcast Control CHannel, in GSM terminology), even if the traffic does not warrant it, thereby increasing equipment costs.
Another known technique deals with the problem of long-distance coverage in cellular networks, by providing for the same base station to operate for both near and far areas. However, this document does not give any information as to the method used for allocating time slots to mobile stations as there is no way of knowing in advance whether they are near or far.
It is therefore an object of the present invention to provide a method for allocating traffic time slots to mobile stations, whether they are near mobile stations or far mobile stations, which method compensates for the problems of the above mentioned known techniques, in particular by maintaining the same number of time slots per mobile station in a given frame, without doubling the number of base stations and broadcast channels.
As will be explained below, the method according- to the invention provides that a mobile station, whether it is a near or a far mobile station, will always be recognised after its fir,' attempt to access the network, thereby increasing further the nhrefficiency of the sysler,: ithout penalising one category of mobile station relative to another.
a To this aim, the method according to the invention, which is, as mentioned above, a method where a base station communicates with mobile stations via a down frame structure and the mobile stations communicate with the base station via an up frame structure, the mobile stations being categorized as near mobile stations or as far mobile stations relative to the base station, wherein the base station performs the following steps: receiving the up frames; analyzing the up frames a) firstly, by using a first time window offset by a first offset relative to the corresponding down frames, the first offset being a nominal guard offset corresponding to a minimum distance for near mobile stations, and b) secondly, by using a second time window offset by a second offset relative to the corresponding down frames, the second offset being an offset of value corresponding to a minimum distance for far mobile stations; ~p I ill 1 -pg 4 1 searching, in each of the time windows, for autocorrelation peaks for channel allocation request time slots, so as to: a) recognize a mobile station requesting channel allocation and b) determine whether the mobile station thus recognised is a near mobile station or a far mobile statior; and allocating in base band a free time slot to each mobile station thus recognised, while providing, for the near mobile stations, an offset of at least one time slot relative to the initially transmitted up frame.
Preferably, in the allocation step, low-rank time slots are preferentially allocated to far mobile stations while higher-rank time slots are preferentially allocated to near mobile stations, so as to group together near and far mobile stations over respective series of successive time slots.
The invention also relates to a base station implementing such a method.
In order that the invention may be readily carried into effect, an embodiment thereof will now be described in relation to the sole accompanying figure, which represents a timing diagram of the various time structures involved in the implementation of the method according to the invention.
The timing diagram of line q of the figure shows the base time structure of a down frame in the GSM system a frame 10 includes several time slots 12, referenced 0 to 7 and conveying data from the base station to the mobile stations.
The timing diagram of line h shows the structure of the up frames, i.e. of the frames sent from the mobile stations to the base station each of these frames 14 also includes eight time slots 16, similar to the time slots 12 of the down frames 10, but offset by a time interval AT 3.TS, TS being the time slot duration.
More information about the structure and role of the down and up frames is given in the above mentioned book "The GSM system".
In a conventional GSM system, i.e in a GSM system operating with near mobile stations only, the base station receives a continuous data flow made up of S" frames, that are in turn made up of time slots, each of which may correspond to a call from a mobile station.
When a mobile station wants to be allocated a traffic time slot, it transmits a frame including a channel allocation request (RA, Random Access, in GSM terminology). The base station must then, firstly, recognize such a message and, -~DU -~1~11~L I- secondly, determine the propagation delay (duration of the return path between the base station and the mobile station) so that it can be taken into account in the time sequencing of data exchanged with the mobile station.
This search is performed by autocorrelation over the successive received bits, the autocorrelation being performed between, firstly, the received signal and, secondly, a reference siynal corresponding to a known portion of the received signal and offset each time by the duration of an extra bit, with a limit of 63 offset bits (63 bits corresponding to a distance of 35 km between mobile station and base station).
The first correlation peak, which is in most cases the main peak, corresponds to the minimum transmission time of the radio signal; the other detected peaks, if any, correspond to secondary paths, for instance after reflection by natural obstacles.
It is well understood that this technique can only be applied in the case of near mobile stations.
In the case of far mobile stations, it is necessary to employ special techniques which, until now, have not brought satisfactory results in terms of efficiency and/or of equipment costs.
In order to compensate for the limitations of the prior art, the invention provides for a double analysis to be simultaneously performed on the received up 20 frames, namely a classical analysis and an analysis with a time offset corresponding 9 substantially to a distance of 35 km, to compare the results of the two analyses and to allocate the traffic time slots to near or far mobile stations accordingly,.
More specifically, the timing diagram of line b of the figure shows the first of these analyses, which is the classical analysis performed by all GSM systems, and the :2S timing diagram of line c shows the simultaneous offset analysis, combined with the previous analysis in a way that is characteristic of the invention.
To facilitate understanding of the example shown in the figure, time slots corresponding to near mobile stations are hatched while time slots corresponding to far mobile stations are crosshatched and unused time slots are blank.
3C The first analysis, which is not offset, only takes into account the near mobile stations. The example shown includes four near mobile stations, which have been detected in the analysis windows FO, F5, F6 and F7 (FO being the signaling channel I -1 that is common to the three traffic channels F5, F6 and F7, which correspond to the three near mobile stations A, B and C).
In line c, four far mobile stations will be identified by an analysis carried out in windows that are offset by a time interval A'T, whose duration corresponds to a distance between a mobile station and a base station of 35 km, i.e. 63 bits: because of this offset, the near mobile stations, which have a short propagation time, will not be detected while the far mobile stations will be detected, for example the three far mobile stations X, Y and Z detected in the windows F'1, F'2 and F'3, the window F'O corresponding to the signaling time slot.
The following step consists, once the up frames have been analyzed, in allocating time slots on the down frame, by recombining in the same base band data corresponding to the windows FO, F1, F2, and data corresponding to the windows F'O, F'1, F'2, The corresponding combination is shown in line d of the figure in which a down frame 18, made up of eight time slots 20 referenced TO, T1, T7, offset relative to the up frames by the value of a time slot (offset TS), consists of the following successive time slots: signaling time slot FO from the near mobile stations (TO), 2d signaling time slot F'O from the far mobile stations (T1), o. traffic time slots F'L, F2 and F'3 from the far mobile stations X, Y and Z (T2, T3, T4), and traffic time slots F5, F6, F7 from the near mobile stations A, B and C (T5, T6, T7).
*T2 Preferably (but this characteristic is not mandatory), the time slots corresponding to far mobile stations and the time slots corresponding to near mobile stations are interleaved so as to group together mobile stations belonging to the same category over the same series of successive time slots, as shown in 22 for the far mobile stations and in 24 for the near mobile stations, so as to allow optimization of the system.
It is thus shown that the simultaneous traffic of six mobile stations can be managed in the same base band, whether the mobile stations are near or far mobile
-I
stations, with a very slight difference in efficiency (six simultaneous mobile stations instead of seven) relative to a classical GSM system that only manages near mobile stations.
The invention thus makes it possible to double the effective cell radius and therefore to quadruple the cell area while only very slightly limiting the performance of the system and at a very low extra equipment cost.
In particular, it can be noted that the method according to the invention, which is implemented downstream of the receiver circuits, does not require any modification to the base station modulators, the only modification taking place in the analysis software, at the level of the sampling input window, therefore without substantially increasing the complexity of the system, in particular of the receive equipment of the base station.
0
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Claims (8)
1. A method for allocating time slots in base band within communications frames for mobile stations in a cellular radiocommunications system of the time-division multiple access type, where a base station communicates with the mobile stations via a dowi. frame structure, and the mobile stations communicate with the base station via an up frame structure, in which system the mobile stations are categorized as near mobile stations or as far mobile stations relative to the base station; wherein the base station performs the following steps: receiving the up frames; analyzing the up frames a) by using a first time window offset by a first offset relative to the corresponding down frames, the first offset being a nominal guard offset of value corresponding to a minimum distance for near mobile stations; and b) by using a second time window offset by a second offset relative to the corresponding down frames, the second offset being an offset of value corresponding to a minimum distance for far mobile stations; searching, in each of the time windows, for autocorrelation peaks for channel allocation request time slots, so as to: a) recognize a mobile station requesting channel allocation; and b) determine whether the mobile station thus recognised is a near mobile station or a far mobile station; and allocating a free time slot in base band to each mobile station thus recognised, while providing, for near mobile stations, an offset of at least one time slot relative to the initially transmitted up frame.
2. A method as claimed in claim 1, wherein, in the allocation step, low-rank time slots are preferentially allocated to far mobile stations while higher-rank time slots are preferentially allocated to near mobile stations, so as to group together near and far mobile stations over respective series of successive time slots. :.3C
3, A base station for a cellular radiocommunications system of the time-division multiple access type, in which system the base station communicates with the mobile stations via a down frame structure, and the mobile stations communicate with the II base station via an up frame structure, and in which system the mobile stations are categorized as near mobile stations or as far mobile stations relative to the base station, the base station including allocation means for allocating time slots in b'-w, band within communications frames for mobile stations; wherein the allocation means comprise: receive means for receiving the up frames; analysis means for analyzing the up frames a) by using a first time window offset by a first offset relative to the corresponding down frames, the first offset being a nominal guard offset of value corresponding to a minimum distance for near mobile stations; and b) by using a second time window offset by a second offset relative to the corresponding down frames, the second offset being an offset of value corresponding to a minimum distance for far mobile stations; search means for searching, in each of the time windows, for autocorrelation peaks for channel allocation request time slots, so as to: a) recognize a mobile station requesting channel ollocation; and b) determine whether the mobile station thus recognised is a near mobile station or a for mobile station; and S2- means for allocating a free time slot in base band to each mobile station thus recognised, while providing, for near mobile stations, an offset of at least one time slot relative to the initially transmitted up frame. ea a S *4 4 *0 a a S e S 0 *e 0 I
4. A base station as claimed in claim 3, wherein the allocation means preferentially allocate low-rank time slots to far mobile stations and higher-rank time slots to near mobile stations, so as to group together near and far mobile stations over respective series of successive time slots.
A method as claimed in claims 1 or 2, wherein sai' radiocommunications system is a GSM system.
6. A base station as claimed in claim 3, wherein said radiocommunications system is a GSM system.
7. A method substantially as herein described with reference to the figure of the drawing.
8. A base station substantially as herein described with reference to the figure of the drawing. DATED THIS TWENTIETH DAY OF DECEMBER 1995 ALCATEL N.V 48 S** a OI t a. e 4* 9 s I 11 ABSTRACT Method and device for allocating communications channels to near and far mobile stations in a TDMA cellular rodiocommunications system, in particular a GSM system The base station performs the following steps: analyzing the received up frames a) by using a first time window (Fi) offset by a first nominal guard offset (3.TS) corresponding to a minimum distance for near mobile stations, and b) by using a second time window offset by a second offset of value (3.TS A'T) corresponding to a minimum distance for for mobile stations; searching, in each of the time windows, for autocorrelation peaks for channel allocation request time slots, so as to: a) recognize a mobile station requesting channel allocation and b) determine whether the mobile station thus recognised is a near mobile station or a far mobile station; and allocating in base band a free time slot (Ti) to each mobile station thus recognised, while providing, for the near mobile stations, an offset of at least one time slot (TS) r~ltive to the initially transmitted up frame. FIGURE TO BE PUBLISHED: Sole figure. g S So S
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9500009A FR2729027B1 (en) | 1995-01-02 | 1995-01-02 | METHOD AND DEVICE FOR ALLOCATING COMMUNICATION CHANNELS TO NEAR AND FAR MOBILE IN AN AMRT CELLULAR RADIO COMMUNICATION SYSTEM, PARTICULARLY A GSM SYSTEM |
| FR9500009 | 1995-01-02 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU4066395A AU4066395A (en) | 1996-07-11 |
| AU692633B2 true AU692633B2 (en) | 1998-06-11 |
Family
ID=9474840
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU40663/95A Ceased AU692633B2 (en) | 1995-01-02 | 1995-12-21 | Large coverage mobile radio base station |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0721290A1 (en) |
| CN (1) | CN1078434C (en) |
| AU (1) | AU692633B2 (en) |
| FI (1) | FI960003A (en) |
| FR (1) | FR2729027B1 (en) |
| ZA (1) | ZA963B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19808948C2 (en) * | 1998-03-03 | 2000-06-15 | Siemens Ag | Method, radio communication system and mobile station for information transmission |
| JP3558125B2 (en) | 2000-10-17 | 2004-08-25 | 日本電気株式会社 | Wireless communication connection destination identification method |
| KR100987286B1 (en) * | 2003-07-31 | 2010-10-12 | 삼성전자주식회사 | A multiple access method in a wireless communication system and controlling system thereof |
| CN100471316C (en) * | 2005-04-28 | 2009-03-18 | 北京邮电大学 | Method for dynamic channel allocation in TD-SCDMA system |
| CN101459642B (en) * | 2007-12-14 | 2011-09-21 | 财团法人工业技术研究院 | Method and device suitable for synchronization signal detection by communication system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0295227A1 (en) * | 1987-06-11 | 1988-12-14 | Telefonaktiebolaget L M Ericsson | Digital time multiplexed mobile telephony system with an effective utilization of every time frame |
| EP0564429A2 (en) * | 1992-03-30 | 1993-10-06 | Telefonaktiebolaget Lm Ericsson | Cell extension in a cellular telephone system |
| EP0614290A1 (en) * | 1993-03-03 | 1994-09-07 | Alcatel Mobile Communication France | Method for allocating a time slot in a frame to a mobile accessing a communication cell and transmitting-receiving base station using the method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0064686B1 (en) * | 1981-05-07 | 1985-07-31 | Alcatel N.V. | Message transmission system |
| DE4400331A1 (en) * | 1994-01-07 | 1995-07-27 | Sel Alcatel Ag | Radio cell extension |
-
1995
- 1995-01-02 FR FR9500009A patent/FR2729027B1/en not_active Expired - Fee Related
- 1995-12-21 AU AU40663/95A patent/AU692633B2/en not_active Ceased
-
1996
- 1996-01-02 CN CN96104394A patent/CN1078434C/en not_active Expired - Fee Related
- 1996-01-02 ZA ZA963A patent/ZA963B/en unknown
- 1996-01-02 EP EP96400005A patent/EP0721290A1/en not_active Withdrawn
- 1996-01-02 FI FI960003A patent/FI960003A/en unknown
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0295227A1 (en) * | 1987-06-11 | 1988-12-14 | Telefonaktiebolaget L M Ericsson | Digital time multiplexed mobile telephony system with an effective utilization of every time frame |
| EP0564429A2 (en) * | 1992-03-30 | 1993-10-06 | Telefonaktiebolaget Lm Ericsson | Cell extension in a cellular telephone system |
| EP0614290A1 (en) * | 1993-03-03 | 1994-09-07 | Alcatel Mobile Communication France | Method for allocating a time slot in a frame to a mobile accessing a communication cell and transmitting-receiving base station using the method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1078434C (en) | 2002-01-23 |
| EP0721290A1 (en) | 1996-07-10 |
| ZA963B (en) | 1996-07-10 |
| FR2729027A1 (en) | 1996-07-05 |
| FI960003A0 (en) | 1996-01-02 |
| CN1137726A (en) | 1996-12-11 |
| FI960003A (en) | 1996-07-03 |
| FR2729027B1 (en) | 1997-04-04 |
| AU4066395A (en) | 1996-07-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MK14 | Patent ceased section 143(a) (annual fees not paid) or expired |