MXPA01004605A - Method of and system for transmitting positional data in compressed format over wireless communication network - Google Patents

Abstract

Latitude and longitude data are compressed by expressing the latitude and longitude not absolutely, but relative to a boundary point in a predetermined subdivision of the earth's surface. The compressed latitude and longitude data are transmitted over a wireless communication network along with the information identifying the cellular service area. Once the cellular service area is identified, the subdivision is identified through a lookup table, and the relative latitude and longitude data are converted into an absolute latitude and longitude.

Description

METHOD AND SYSTEM FOR THE TRANSMISSION OF POSITION DATA IN A COMPRESSED FORMAT IN A WIRELESS COMMUNICATION NETWORK • Field of the Invention The present invention is directed to a method and to a system for transmitting the latitude and longitude of a transmitter, such as a cell phone apparatus in a compressed form in such a way as to conform within a small payload or data packet.

Background of the Invention It is often desirable for a wireless communication unit to transmit its location to a high degree of resolution. For example, a system to track the locations of trailers equipment, with a GPS receiver (Global Positioning System) in each trailer to determine the location of the trailer, and a unit wireless communication to inform the headquarters, the location of the trailer. However, as will be shown, the transmission of the location comprises a large amount of undesirable data transmission. 25 Latitude measurements are based on angular measurements of north south from the equator, which is defined as 0 ° latitude. In this way, the North Pole has a latitude of 90 ° north, while the South Pole has a latitude of 90 ° south, so that the range of possible latitudes is 180 °. In other words, to express a latitude that is within a degree, 180 units of resolution are required. Each degree is divided into 60 minutes, and each minute is divided into 60 seconds. Each second of latitude is equal to approximately 30,805 meters. In this way, the range of possible latitudes is 180 ° x 3,600 seconds / 0 = 648,000 seconds, so that expressing a latitude within a certain time requires 648,000 resolution units. Such a number is expressed in apocryphal binary notation as 1001 1110 0011 0100 0000; consequently, to express a latitude within a second in binary notation, 20 bits of data are required. The length measurements are based on anchor measurements of the east or west from the Green ich Meridian, which is defined as 0 ° longitude. Each second of length is equal to approximately 30,805 meters in the Equator or 9,455 meters to 70 ° of north or south latitude. The range of possible lengths is from -180 ° to + 180 °, or 360 °, which is twice the range of possible latitudes. In this way, the length requires twice the number of • resolution units that latitude, that is, 5,296,000 resolution units to express the length within one second. Such resolution requires no less than 21 bits. Therefore, to combine latitude and longevity, each within a second, in a single message, is • 10 require 41 bits. However, many information and telemetry systems, such as the Cellemetry (Data Service), transmit data in 32-bit packages or useful cartels, consequently, the 41 bits of latitude and longitude data exceed a second packet, and that reason, they increase the transmission costs. Accordingly, there is a need to express latitude and longitude in 32 bits or less, to reduce transmission costs. A common technique used by systems mobile, it is first to transmit the latitude and longitude of an original position in two 32-bit transmissions and to transmit each additional position in 32 bits, transmitting only the difference of the original position, which in this way is used as a difference reference. When the difference is not adjusted to 32 bits, the latitude and longitude, each in 32 bits, are completely transmitted to form a new difference reference.

• However, full latitude and longitude must be transmitted at least once and must be retransmitted as long as the difference from the original position is greater than a predetermined amount. As a consequence, this technique does not take into account an increase too much Significant efficiency, partirly for a rapidly moving vehicle, for which full latitude and longitude must be retransmitted frequently. A known technique to identify the location of a cell phone or other mobile telephone radio device, involves the use of an identification number of the mobile switching center (SCID). The MSCID and its use are defined in the IS-41 standard, which is described in Document No.

TIA / EIA / IS-41 of the Association of the Telecommunications Industry, published by Global Engineering Documents, 15 Iverness Way East, Englewood, Colorado 80112, E.U.A. Before the MSCID and its use are described in detail, the division of E.U.A. in areas of cellular service. The cell phone system of the following description is typical of the commercial cellular telephone systems defined by the TIA / EIA 553 standard of the Association of the Telecommunications Industry and its derivatives. This standard can also be obtained from Global Engineering Documents at the address indicated above. In 1981, the FCC adopted rules, creating a commercial cell phone radio service. The FCC set aside 50 MHZ of spectrum in the frequency band of 800 MHZ for two competent cellular systems in each market (25 MHZ for each system). From the beginning, the FCC has encouraged competition in the cellular radio market by dividing the available spectrum into two channel blocks, one for telephone companies with local cabling lines and one for companies without wiring, for example, Radio Common Carriers (RCC). The FCC established rules and procedures for licensing cellular systems in the United States and its Belongings and Territories. These rules designated 305 Metropolitan Statistical Areas (MSAs) defined by counties according to the 1980 census. The FCC reviewed the MSAs in some of the 30 major markets. The Gulf of Mexico Service Area was added as Market 306. Of the remaining counties that were not included in the MSASs, the Commission created 428 Rural Service Areas (RSAs), for a total of 734 cellular markets. A cellular system operates by dividing a large geographic area of service into cells and allocating the same channels to multiple, non-adjacent cells. This allows the channels to be reused, increasing the efficiency of the spectrum. As a subscriber travels through the service area, the call is transferred (connected) from one cell to another without noticeable interruption. All cells in a cellular system are connected to a Mobile Telephony Switching Office (MTSO) through landline or microwave links. The MTSO controls the switching between the Public Switched Telephone Network (PSTN) and the cell site for all calls from wiring to mobile line and mobile to wiring line. The MTSO also processes the mobile unit status data received from the cell-to-site controllers, switches the calls to other cells, processes diaqnostic information, and collects billing statistics. Each cell is served by its own radio telephone and control equipment. Each cell is assigned to a group of voice channels and a control channel with adjacent cells assigned to different channels to avoid interference. The control channel • transmits data to and from mobile / portable units. The control data warns the mobile / portable unit that a call is coming from the MTSO or, conversely, notifies the controller that the mobile / portable unit wishes to place a call. The MTSO also uses a channel of • 10 control to notify the mobile / portable unit, which voice channel is being assigned to the call. The 25 MHZ assigned to each cellular system currently consists of 395 voice channels and 21 control channels. 15 The MSCID is related to the foregoing as follows. The MSCID consists of three • OCTETS. The first two OCTETS, called the "Market ID", contain the system identity (SID), which is assigned by the FCC and identifies the cellular market. For example, SID 0003410 identifies an Atlanta metropolitan service area (MSA) licensed by the FCC and may include contiguous rural service areas (RSA) owned by the same dealer. MSA / RSA are geographic areas specific ones defined by the FCC for purposes of granting licenses. The last OCTET, called the "switch number", identifies the switching entity of the licensed cellular operator. For example, the four switching entities of a cellular operator in the metropolitan service area of Atlanta are identified as from 000340110 to 000340410. The MSCID is used in the following way. When a cell phone contacts a transmitter in a cell, the cell phone transmission to the cell includes the following information: the mobile identification number assigned to that cell phone and the electronic serial number (ESN) of said cell phone. The cell transmits that information to the switch provided by said cellular carrier in said location. The switch validates the cell phone by sending a message to the local system of that cell phone in a network compatible with the IS-41 standard, such as an SS7 or X25 network. That message includes the telephone number and ESN provided by the cell phone and also includes route information for the message, that is, point codes for the origin and destination of the message. In this way, the MSCID identifies the location of the cell phone within a metropolitan service area, rural service area or other cell phone market and does not need to be transmitted from the cell phone to the cell, since the switch already knows your own MSCID. However, such a sharp identification of the location is not sufficient for all purposes, and the prior art does not contemplate the use of the MSCID to identify the location of the cellular telephone within a smaller area.

Summary of the Invention In view of the background, it should be clear that there is still a need in the matter of a method and system for transmitting position data, and in particular, data of latitude and longevity, in a compressed form and to a high degree of resolution. This, therefore, is a main object of the present invention to encode latitude and longitude information, each within a second, in a short data packet such as 32 bits. It is a further object of the present invention to do the above without having to transmit at all times all the latitude and longitude information.

In order to achieve this and other objects, the present invention is directed to a system and method that depends on unequal position information that is • being transmitted by several systems, including 5 telephony signaling systems based on the SS7. This desiqual position information is a "point of origin" identifier that identifies the area in which the transmitting apparatus is located. Subsequently, it is enough for the latitude and • 10 lengths are only specified in relation to an agreed or predetermined subdivision of the Earth that contains that area, in order to cross the entire Earth. That technique combines high data compression with fine resolution. One embodiment of the present invention divides the Earth into subdivisions that measure 9 ° of latitude by 36 ° of longitude and subsequently express the information of latitude and longitude relative to a particular point in each subdivision. In this modality of the present invention, the latitude and longitude in seconds can be encoded in 15 and 17 bits, respectively, for a total of 32 data bits. The transmission device transmits that 32-bit word, which is augmented by the switch adding the MSCID (identification number of the mobile switching center) that identifies the coverage area of the cellular service carrier. A receiving apparatus receives the transmission and redirects the latitude and longitude information of the 32-bit word and the MSCID in the following manner. The MSCID is used to identify the subdivision through the use of a query table which corresponds to each MSCID with the subdivision which contains the area identified by the MSCID. The location of the subdivision and the 32-bit word are sufficient to identify the location within one second of latitude and one second of longitude.

Brief Description of the Drawings A preferred embodiment of the present invention will be described in detail with reference to the drawings, in which: Figure 1 is a drawing showing a portion of the surface of the Earth with subdivisions, cell towers and areas of cellular service; Figure 2 is a drawing showing a trailer from which the compressed position data is transmitted and a base station receiving the compressed position data transmitted from the trailer; The Fiqura 3, is a drawing that shows a location tracking that again derives the position of the trailer from the compressed position data; and Figure 4 is a flow chart showing the operations that are carried out in the trailer shown in Figure 2 and the location tracking shown in Figure 3.

Detailed Description of the Invention A preferred embodiment will now be described in detail with reference to the drawings, in which like elements are represented by similar reference numerals. The operation steps listed are shown in the flow chart of Figure 4. Figure 1 shows a portion 101 of the surface of the Earth divided into lines of latitude 103 and lines of longitude or meridians 105 within the subdivisions. 107 measuring 9 ° latitude by 36 ° longitude. A wireless network is deployed on that portion of the Earth's surface. The wireless network includes one or more cellular towers 109 in its cellular service area 111. In this way, each cellular service area 111 correlates to a specific subdivision 107. A cellular service area that does not fully fall into a subdivision 107 is correlated with that in which it is dominant.

• This wireless network can be a public cellular network 5 or a proprietary network. As shown in Fiqura 2, a mobile unit 201, such as a trailer, can be equipped with a GPS receiver 203 and a wireless communication unit 205, or the integration thereof, which is compatible with the wireless network. The trailer 201 calls in its location as follows. The wireless communication unit 205 establishes a communication link in step 401 through its antenna 206 with the cellular tower 109 of the station base 207 nearest. That base station 207 and other base stations in the same cellular market are connected to a switch 209, which has a previously allocated MSCID and transmits the SID portion of the MSCID back through the base station 207 to the wireless communication unit 205. The GPS receiver 203 determines the location in one second of latitude and longitude in step 403 and communicates the position data representing the location to the wireless communication unit 205. 25 The position data is compressed or reduced in step 405 to fit within a data packet or payload of a previously determined small size, such as 32 bits, and subsequently transmitted in step 407 to the base station 207. In 5 the preferred embodiment, as described above, latitude and longitude are reduced to 15 bits and 17 bits, respectively. This reduction can be done in any of the various ways. Higher order bits can simply be eliminated. Alternatively, the wireless communication unit 205 can receive the SID from the base station 207 and determine the subdivision in which the trailer 201 is located by entering the SID into a look-up table 208.

Said reference tables are known in the art of electronics and can be implemented in any suitable memory. Said look-up table is viable due to the correlation described above of the cellular service areas and subdivisions.

Subsequently, the latitude and longitude received from the GPS receiver 203 can be converted into the latitude and longitude relative to a corner or other point previously determined in the subdivision. The base station 207 transmits the information of latitude and longitude of data in conventionally reduced size by means of switch 209 and network 301 to a location scan 303 shown in Figure 3. However, latitude and • length are small, the location scan 301 5 again derives the complete (or absolute) information of latitude and longitude. One way of doing this, uses the MSCID, starting from that as already explained, it is known in the art, for the switch to transmit the MSCID to the tracking of • 10 location. Thus, when the location scan 303 receives the data packet containing the reduced amount of position data in step 409, the location scan 303 also receives the MSCID. The location scan 303 introduces the portion SID of the MSCID, and optionally, also the entity portion of the switch, in a look-up table 305 to determine the subdivision in step 411. From the subdivision and the transmitted latitude and longitude information, latitude and longitude The complete ones, each within one second, can be derived again using an appropriate circuitry system 307 in step 413. In short, the latitude and longitude data are sent in a compressed or reduced format and are reconstructed using data that is transmitted in any way through the wireless network, ie the MSCID. In this way, latitude and longitude data are transmitted more efficiently than in the prior art. Although a preferred embodiment of the present invention has been described in detail above, those skilled in the art who have reviewed the present disclosure will readily appreciate that other embodiments may be considered within the scope of the present invention. For example, although the latitude and longitude data have been considered to be determined within a second, the present invention can be implemented at any resolution allowed by the GPS or other technology used to detect the position. Furthermore, while the position has been expressed in terms of latitude and longitude, the present invention could simply be applied to position data in any other form and in one, two or three dimensions. Additionally, although the preferred embodiment has been described for use with cellular systems in accordance with the TIA / EIA 553 standard, the present invention is equally applicable to other radiotelephone systems. For example, the cellular network can be a proprietary network, in which case the reduction of latitude and longitude data can be carried out in the switch. In such a case the wireless communication unit 205 does not need to know the MSCID. On the other hand, although the preferred modality allows locations across the Earth, limited only by the accessibility of the radio telephone equipment, a smaller macrocosm, such as a single continent, can be accepted and subdivided. Accordingly, the present invention should be construed as limited only by the appended claims.

Claims (11)

1. NOVELTY OF THE INVENTION Having described the present invention it is considered as novelty and therefore, it is claimed as • property contained in the following: 5 CLAIMS 1. A method for transmitting absolute position data in a compressed form, the absolute position data identifying a position within a macrocosm, wherein the method comprises: converting the absolute position data to relative position data, indicating the relative position data, the position within a predetermined subdivision of the macrocosm; and transmit the relative position data and 15 identify enough information to identify the predetermined subdivision of the macrocosm.
2. 2. The method according to claim 1, wherein the absolute position data comprises 20 latitude and longitude data.
3. 3. The method according to claim 2, wherein the macrocosm is the surface of the Earth.
4. 4. The method according to claim 3, 25 where the predetermined subdivision is defined by a range of latitudes and a range of lengths.
5. 5. The method according to claim 1, wherein step (b) is carried out in a telephone radio network. The method according to claim 5, wherein the identification of the information comprises information identifying a switch of the radio telephone network. 7. A method for receiving relative position data indicating a position within a predetermined subdivision of the macrocosm and deriving absolute position data by identifying the position within the macrocosm, wherein the method comprises: receiving a transmission of relative position data and identification of sufficient information to identify the predetermined subdivision of the macrocosm; and from the relative position data and the identification of the information received in step (a) derive the absolute position steps. 8. The method according to claim 7, wherein the absolute position data comprises latitude and longitude data. 9. The method according to claim 8, wherein the macrocosm is the surface of the Earth. 10 The method of compliance with the • claim 9, wherein the predetermined subdivision is defined by a rank of latitudes and a range of lengths. The method according to claim 7, wherein step (a) is carried out in a telephone radio network. • The method according to claim 11, wherein the identification of the information comprises information identifying a switch of the radio telephone network. 15 13. A method for transmitting and receiving absolute position data in compressed form, • identifying the absolute position data, a position within a macrocosm wherein the method comprises: converting the absolute position data to relative position data, the relative position data indicating the position within a predetermined subdivision of the macrocosm; transmit the relative position data and 25 identify sufficient information to identify the predetermined subdivision of the macrocosm; receive the relative position data and the • identification of information transmitted in step 5 (b); and from the relative position data and the identification of the information received in step (c), derive the absolute position data. 14. The method of compliance with • 10 claim 13, wherein the absolute position data comprises latitude and longitude data. 15. The method according to claim 14, wherein the macrocosm is the surface of the Earth. 16. The method according to claim 15, wherein the predetermined subdivision is defined by a range of latitudes and a range of lengths. 17. The method of compliance with 20 claim 13, wherein steps (b) and (c) are carried out in a telephone radio network. The method according to claim 17, wherein the identification of the information comprises information that 25 identifies a switch of the telephone radio network. 19. A system for transmitting absolute position data in a compressed form, identifying the • absolute position data a position within a macrocosm, wherein the system comprises: conversion means for converting the absolute position data to relative position data, the relative position data indicating the position within a predetermined subdivision • 10 of the macrocosm; and transmission means for transmitting absolute position data and identifying enough information to identify the predetermined subdivision of the macrocosm. 20. The system according to claim 19, wherein the absolute position data comprises latitude and longitude data. 21. The system according to claim 20, wherein the macrocosm is the 20 surface of the Earth. 22. The system according to claim 21, wherein the predetermined subdivision is defined by a range of latitudes and a range of lengths. 23. The system according to claim 1, wherein the transmission means comprises a telephone radio unit for use with a telephone radio network. . The system according to claim 23, wherein the identification of the information comprises information identifying a switch of the telephony radio network. . A system for receiving relative position data by indicating a position within a predetermined subdivision of the macrocosm and deriving the absolute position data by identifying the position within the macrocosm, wherein the system comprises: receiving means for receiving a transmission of the position data relative and identification of information sufficient to identify the predetermined subdivision of the macrocosm; and derivation means for deriving the absolute position data from the relative position data and the identification of the information received by reception means. The system according to claim 25, wherein the absolute position data comprises latitude and longitude data. . The system according to claim 26, wherein the macrocosm is the surface of the Earth. . The system according to claim 27, wherein the predetermined subdivision is defined by a range of latitudes and a range of lengths. . The system according to claim 25, wherein the receiving means comprises means for receiving a transmission made in a telephony radio network. The system according to claim 29, wherein the identification of the information comprises information identifying a switch. of the radio telephone network. . A system for transmitting and receiving absolute position data in compressed form, the absolute position data identifying a position within a macrocosm, wherein the system comprises: conversion means for converting the absolute position data to relative position data, indicating the position relative data the position within a predetermined subdivision of the macrocosm; and transmission means for transmitting the relative position and information identification data sufficient to identify the predetermined subdivision of the macrocosm; receiving means for receiving the relative position data and identification of the information transmitted by the transmission means; and derivation means for deriving, from relative position data and the identification of the information received by the receiving means, the absolute position data. . The system according to claim 31, wherein the absolute position data comprises latitude and longitude data. . The system according to claim 32, wherein the macrocosm is the surface of the Earth. . The system according to claim 33 wherein the predetermined subdivision is defined by a range of latitudes and a range of lengths. 35. The system in accordance with the • claim 31, wherein the transmission means and the receiving means comprise means for communicating with each other in a radio telephone network. 36. The system according to claim 35, wherein the identification of • 10 the information comprises information that identifies a switch of the radio telephone network.