SE511153C2 - Altering transmission parameters in radio transmitter for high security - Google Patents

Abstract

The transmitters send information simultaneously to the receivers over a common radio frequency. Information from a transmitter is distributed over one or more blocks. All blocks for each of the transmitters form a frame. Information in each block is addressable to a specific receiver or group of receivers, a specific part of the blocks being not wholly used by the information. A specific transmitter, upon transmission of test information, is allocated a specific block in a frame for identifying the transmitter for the receivers. Only one transmitter transmits test information in the part of the specific block which is not wholly used for other information.

Description

10 15 20 25 30 35 511,153 of the signal on transmission from the various stations nerna. The signal must be synchronized during transmission. to minimize the synchronization error at the recipients due to the running time differences that exists to a receiver in the system.

The differences in running time are due to the in most cases are at different distances from the various interceptable transmitters. Another problems that may arise under adverse conditions is negative carrier interference between stations, at the signal can be temporarily turned off. This is caused of uncontrolled carrier offset between stations in combination with equal signal strengths between walking transmitter at a receiving location.

DESCRIPTION OF THE INVENTION TECHNICAL PROBLEM In radio communication in areas with a plurality transmitters transmitting simultaneously on the same frequency there is a need to change parameters in transmission stations to optimize reception conditions.

Simultaneous transmission with several transmitters on the same frequency in an area means that reception of digital speech information is made more difficult in those areas where negative interference between the transmitters occurs in some form. If the signals from several stations are equal In terms of strength at a receiver, it is important that the signals arrive at the receiver within certain time interval and with a controlled carrier offset between the transmitters. If this does not happen, it is detected incorrectly signal and reception are eliminated within the current area where the recipient is located. It's in this mode it is desirable to change the stations' transmission parameters to improve reception conditions. The there may be a need to make this change even during 10 U 20 25 30 35 La' 511 153 operation, if the traffic situation and those in the area only the recipients require this. A measuring receiver, which is mobile and has its geographical location determinable. must be able to identify which station is being received.

This receiver must be able to assess the signal characteristics and thus the reception conditions of the the place.

The measurement result must be able to be fed back to the system for automatic change of the station's transmission parameters.

Here, the present invention seeks to solve the above written problems.

SOLUTION A radio communication network, with several transmitters within an area has been arranged. The same nominal transmission frequency is used by base stations within a common area. In order for the information, which consists of digital information, shall be transmitted simultaneously throughout the network accurate synchronization of the stations is required.

The synchronization takes place, for example, via satellite as transmits a global time signal, or with another synchronized sering algorithm, e.g. with the base stations included in synchronization chains in a “master-slave” relationship countries. Information from the respective radio transmitters, sent at predetermined times. The time difference between receiving messages from the various stations in the system was allowed to differ corresponding to a predetermined one part of an information bit in the message sequence.

The receivers receive signals from the stations within whose the coverage area of the recipients is located. Since the signal is transmitted simultaneously from different transmitter stations down when the signal receivers with different delay pa due to time differences. This time difference in unfavorable cases, the detection of the the digital signal cannot be made unambiguously by the 10 U 20 25 30 35 511 155 AN clean despite sufficient signal strength. When measuring in the system with measuring receivers registers these signals characteristics in different places together with statement, this is then transferred to the station nerna. The measuring receivers can be equipped with means for identification of its geographical location, indicating the water of position can be automated.

Information from the transmitters is transmitted in blocks, destinations to predetermined recipients or predetermined group of recipients. A number of such blocks are housed in a frame. Each block contains information section and address information. Since the information section below certain periods are only partially used, finning this. In these vacant gaps were sent out instead test information intended to be received by mobile measuring receivers within the range of the station. For that the measuring receiver must be able to identify the current transmitters and obtain optimal measurement possibilities takes place in this mode only broadcast from a station eat gangs. Each station is assigned a specific one blocks within the framework. The test information contains data indicating which station in the receiving area is transmitting there. In a development of the invention one can use this data to avoid loading the station into one predetermined block. The test information is registered in the measuring receiver and an analysis of the signal characteristics is done. The registered data and signal properties then returned together with a position indication to the radio communication system for any otherwise adjustments. The feedback takes place on its own known method, for example by the measuring receiver being seen with transmitters for retransmission of information or that each measuring receiver returns the information utilization of other technologies, such as data transmission via the telephone network.

In a development of the invention, the measuring receiver uses the test information on which station 10 15 20 25 30 35 511 153 which transmits. With this procedure, the stations are not read to specific blocks. This means that flexibility little is obtained by measuring the reception ratio from the respective stations. You can in this case place the measurements in some or some of the blocks when other blocks due to high traffic load can not be used for test information. In this case the recipients are provided with means for identification of the transmitters.

The test information is placed in the information section final. This means that test information is transmitted bar even if other information is transmitted via the block.

However, the test information cannot be transmitted in the case the regular information fills the block.

The test information is transmitted when from any point of view considered optimal, e.g. when the traffic intensity increases or when the operator of the radio system considers need it. In a fully automated system the initiation of the transmission of test information is controlled tion of higher lying system functions.

The measurement result is used to identify areas where the signal is distorted. In areas with distortions signal, the reception ratio can be improved by, for example: change of transmitted power or memory power direction, change of synchronization offer set or change of the off-road offset at any of the current stations. The consequences of this are that one new area arises where the signals become distorted rade. By an appropriate selection of transmission parameters is it is possible to locate this critical area a geography where the damage is minor or non-existent.

In a future fully automated system, it is possible conventional receivers also function as measuring receivers and that these return the measurement result to the stations, this is probably not the case in a normal paging system with today's technology. 10 15 20 25 30 511 153 In this case, the stations use the test information for adjusting the transmission parameters for the best use of the network in all situations with regard to the traffic situation.

BENEFITS The method involves transmitting signals with larger security can be detected by receivers. Furthermore, opportunity to redistribute good reception conditions from areas with little need for reception, to weak areas in terms of reception but in need of better reception.

Furthermore, continuous follow-up of radio systems is allowed. reception conditions in different geographical areas fishing areas. It is also possible to redistribute radio coverage in different areas with regard to prevailing traffic needs.

The possibility of using mobile hand-portable measuring receiver for recording signal conditions at different geographical locations constitute an additional part, hand portability is in principle impossible without sending test information as it simplifies the measuring receiver construction significantly. The measuring receivers registers signal properties and geographical location parallel during measurement. The station identification is in the previously mentioned test information which broadcast from each radio station. The advantage of a test information that is normally only sent when the traffic intensity so it allows is that the radio system the system is minimally affected in terms of capacity.

DESCRIPTION OF FIGURES Figure 1 shows a frame. 10 15 20 25 30 511 153 Fig. 2 shows a block.

FÖRIHN% ÄGEN'LHUWÖRINCEHWHÜU In the following, the inventive idea is described with reference to to the figures and designations therein.

A system with a number of radio stations and gare considered. The radio stations work on the same nominal carrier frequency. The information that is broadcast from the stations is digital and simultaneous. In the reception the information shall appear simultaneously from the dio stations on the walking distance between the station and the receiver are the same.

In order for the signals from each station to arrive at the same time to recipients who are located at the same walking distance from the stations it is required that stations have been synchronized. When synchronizing, use, for example, global time signals that are transmitted with high precision from satellite, or sink chains.

The internal clock located in the stations is set with an accuracy necessary for the system functionality.

In addition, test information is sent at the selected time with bit patterns that enable the type of measurement man want to perform, it can e.g. in the case of bearing road measurements synchronization measurement, 'man made noise' or signal strength measurement. The test information also includes base station identification. The test information can, and should in a simultaneous type digital radio system, broadcast from one base station at a time. Namely, when other stations in the area audible stations have broadcast subsistence. With this procedure, a single clear measuring receiver design and an optimization of measurement performance. 10 15 20 25 30 35 -n 511 153 Fig. 1 shows a frame in which information is transmitted separately. quentially, comprising a number of blocks, 1-n. Each block contains information addressed to a recipient or a group of recipients. The block includes including an information part of the recipients identifies messages. The information section contains a varying amount of information depending on the the length of the division. This means that the information part contains space that is useful in those cases whole capacity is not used. This part is used, when so allowed, for test information.

When transmitting test information, this is transmitted in for example, the information part of the 1st block. In order to the measuring receiver shall not be disturbed by other transmitters transmission takes place only from one transmitter. The measuring receiver identifies the transmitter by transmitter identification included in the test information. Alternatively, each can transmitters be read to a specific block. The receiver identifies in this case the transmitter by identifying specify which block is received.

By registering the reception conditions with measuring receivers at different locations within the stations coverage areas, it is possible to determine whether their parameters should be adjusted or not. Information regarding the measurement result is then transferred to central units for adjusting the stations' data. The transfer takes place in a manner known per se, for example by the measuring receivers transmitting the results on a radio channel received by a monitor function. Information is in this way conti- registerable with regard to the reception conditions landena. The received information is received and are traded whereby continuous adjustments regarding the the transmission parameters of different stations can be entered. The it is also possible for the measuring receivers to store information in a memory or the like. The information transmitted in the latter case by playback in 10 Ü 20 25 30 35 511 1515 for intended devices at the central functions nerna. It is also possible to transfer information via telecommunications or data networks. In this case, the the information is converted into formats that are transferable in respective networks. The central funds receive information and take the necessary measures In the bitstream transmitted from the base stations ings information to be received by different recipients.

Each recipient identifies their part of the message for decoding. Message sent from a state tion appears to the recipient at time t after broadcast. The same message sent from a station arrives at the receiver at the time ten T after dispatch. The possibility for the recipient to detect transmitted signal correctly is time dependent the point when the respective signal reaches the receiver. If the time difference T-t exceeds the acceptance limit for detection, the risk of incorrect detection is obtained signal, bit error.

To avoid error detection, the stations have chronicled so that the signal, from each station, received within a time interval corresponding to a designated part of an information piece as before.

If T-t exceeds the acceptance limit, there is a possibility to adjust this by synchronizing other ring offset at one of the base stations. Determination of said time interval takes place with regard to met functionality and to the running times that can arise. The recipients also receive varying shooting conditions in different areas. the variations are partly due to geographical circumstances partly on the mutual impact of the stations on drag. Thus, the signal is amplified in certain areas respectively weakened in other areas.

By other parameters such as sanding effect, synchronization offset or carrier offset, may be weak reception areas of others to acceptable reception 10 15 20 10f ' 511 153 areas. However, this happens at the expense of areas that previously had acceptable reception conditions attitudes. By selecting the stations' sand parameters However, it is possible to redistribute the same areas to geographical areas with little electricity laughs no radio traffic.

The measuring receivers go through the covers' areas of the sanders when measuring the system. Information on measuring receiver their geographical location and measurement results are registered.

This data is transmitted to the stations for action. Changing the station's sanding parameters then takes place if the need arises.

In the system existing recipients can in the future possibly act as a measuring receiver for automatic change of the sand parameters with regard to prevailing situation. For example, this allows an optimization of the reception ratio is controllable to the area that is currently relevant.

The invention is not limited to that of the above invention. said the embodiment but can submit modifications within the framework of subsequent patent claims and inventive thinking.

Claims (6)

10 U 20 25 30 35 “511 153 PATENT REQUIREMENTS A method in a radio communication network, comprising a number of independent transmitters and a number of receivers, wherein the transmitters transmit information simultaneously to the receivers over one for which the information from one block, all blocks for each of the transmitters form a frame and to a system common radio frequency transmitter is distributed over one or more of which, where the information in each block is addressable to a particular receiver or group of receivers, a certain part of said block not being fully utilized by said information, characterized in that a particular transmitter is assigned a specific when transmitting test information. block in a frame for identifying the transmitter for the receivers, that said test information is transmitted in said part of a block which is not fully utilized by the information (INFO), block completely transmits in a certain part of the block that only one transmitter tests the information in said which is not utilized for other information; and that the receivers receive the test information and, on the basis of their geographical location, identify the transmitter whose transmitted test information has been received and record the reception conditions of that transmitter and return them to the system for any adjustments. A method in a radio communication network, comprising a number of independent transmitters and a number of receivers, wherein the transmitters transmit information simultaneously to the receivers over one for which the information from a block, the system common radio frequency, transmitter is distributed over one or more of each block for each one of the transmitters forms a frame and blocks are for a specific receiver or group of receivers, a certain one where the information in each addressable part of said block is not fully utilized by said information, P06002 erahale 99-05-21 10 15 20 25 511 153 12, characterized in that said test information is transmitted in said part of a block which is not fully utilized by the information (INFO), that a certain transmitter in transmitting test information in a block also transmits its station identity, that only one transmitter transmits in one block the test information in said part of the block that is not fully used for other information; and that the receivers receive the test information and, on the basis of its geographical location, identify the transmitter whose transmitted test information has been received and record the reception conditions of that transmitter and return them to the system for any adjustments. Method according to Claim 1 or 2, characterized in that the radio communication network preferably consists of a paging system. A method according to claim 1 or 2, characterized in that each block contains information about which transmitter the test information emanates from. A method according to claim 1 or 2, characterized in that the receivers are provided with identification means for determining which transmitter is being received. Method according to claim 1 or 2, characterized in that the test information is preferably stored at the end of the information part of the block. PO6002 c fi hale 99-05-21