KR950013303B1 - Method of maintaining an established connection in a mobile radio system conprising both analog and digital radio - Google Patents

Abstract

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Description

How to Maintain Connections in Mobile Wireless Systems with Analog and Digital Radio Channels

[Brief Description of Drawings]

1 is an exemplary diagram illustrating a cell wireless mobile system having a cell, a mobile switching center, a base station and a mobile station.

2 is an exemplary diagram illustrating the use of multiple radio channels and radio channels in a frequency band in the cellular mobile system according to FIG.

3 illustrates the use of a wireless channel according to FIG. 2 for a control channel, an analog communication channel and a time division multiplex digital communication channel in a cellular mobile radio system according to FIG.

4 is an illustration of a burst divided by a guide space over a radio channel used as a digital communication channel in the time division multiplex according to FIG. 3 in the Cellular mobile radio system according to FIG.

5 is an exemplary diagram illustrating a base station in a cell-based mobile radio system according to FIG. 3 with a radio channel used in accordance with FIGS. 2-4.

6 is an exemplary diagram illustrating a mobile station in the cellular mobile radio system according to FIG. 1 communicating with a base station according to FIG. 5 in a control and digital communication channel in accordance with FIGS. 2-4.

7 is an exemplary diagram illustrating actual error ratio and error ratio estimation of a digital channel by using an additional channel coder at a receiving side of a base station or a mobile station.

8 illustrates an impulse response of a digital radio link including a method of estimating, transmitting and receiving time dispersion in a digital channel using a synchronization word.

Detailed description of the invention

[Technical Field]

TECHNICAL FIELD The present invention relates to the technical field of mobile radio systems, and more particularly, to automatic radio systems having analog and digital channels. It is an object of the present invention to maintain the connection of digital radio channels by providing an equalizer in the mobile station even if the ejection of the available digital radio channels exceeds the maximum time dispersion. It will also refer to techniques in the field of conversion in mobile radio systems.

[Background of invention]

A mobile radio system transmits information in analog between a base station and a mobile station. That is, information is transmitted between a base station and a mobile station using an analog modulated radio signal in an analog radio channel. Frequency multiplexing enables analog mobile radio systems to have multiple radio channels. For example, the nordic mobile telephone system (NMT) is an analog mobile radio system with many radio channels.

Recently, however, it has been proposed in a mobile wireless system for digitally transmitting information between a base station and a mobile station. That is, digital information is transmitted between mobile stations on the digital radio channel. Of course, more channels can be made using frequency multiplexing in digital mobile radio systems. To create more channels in digital mobile radio systems, digital radio channels must be assigned radio frequencies in time multiplex. GSM (pan european mobile radio system) is a representative of the digital mobile radio system. Digital technology has significant advantages in mobile wireless systems. Therefore, the digital technology will be introduced here. On the other hand, the existing analog mobile radio system will use a frequency band suitable for digital systems. The disadvantage is that if a large piece of equipment is installed in an existing analog system, the existing analog system cannot be immediately converted into a digital system. Therefore, the analog channel of analog system having many analog channels in frequency multiplex can be continuously changed from time multiplex to multiple digital channels. In the United States (USA) it was proposed to change each analog channel from a time multiplex to three multiplexes. Over the years, these mobile radio systems have come to include digital radio channels that digitally transmit information using analog modulated radio signals. Therefore, mobile stations have been able to use analog radio channels and digital radio channels for a long time. Digital mobile radio systems have a problem that time dispersion occurs in digital radio channels due to refraction and multipath propagation unless special measures are taken.

Time variance causes the propagation characteristics to change from one position to another. Even if time dispersion occurs, it is well known that an equalizer must be installed on the receiving side of a mobile radio system in order to transmit information stably. Equalizing can shorten or lengthen time dispersion. One way of describing the equalizer's ability to cope with time dispersion is to describe how the equalizer had the maximum time dispersion per microsecond, and another way is to explain how many symbol time spans the equalizer handled. Equalizers are compounded as the maximum time dispersion per microsecond and the number of symbol lifetimes increase, increasing cost and power consumption.

Therefore, the focus was on the fabrication of a mobile radio system in which parts of the equalizer are no larger than necessary. The GSM mentioned above is designed to allow the equalizer to handle a maximum time variance per 16 microseconds equal to four symbol time intervals. The above mentioned mobile radio channel in the USA with a digital analog radio channel handles the maximum time dispersion per 60 microseconds in the digital radio channel. This is longer than the duration of one symbol and shorter than the duration of two symbols.

Transmitting information analog to the analog radio channel of an existing analog mobile radio system, such as the conventional form of NMT or USA mentioned above, results in less refraction and multiplex propagation in digital radio channels than in digital systems.

Brief description of the invention

Equalizers become more complex and cost and consume more power as the maximum time dispersion per microsecond and the number of symbol lifetimes increase. This is a problem when the mobile radio system needs long time dispersion. This problem is even greater when no parameter can be selected. In other words, the problem is further increased when the analog radio channel cannot be converted into a time multiplex digital radio signal by changing analog technology to digital technology in a mobile wireless system. If the time dispersion of the mobile radio system is processed continuously, it causes a bigger problem if the time dispersion is larger than the symbol time interval of any integer and smaller than the symbol time interval of the next integer. If all time variances are handled with a Viterboiler, the equalizer must be very large. The present invention addresses this problem in mobile wireless systems with analog and digital radio channels. The present invention simply solves the above problem by lowering the sensitivity of the analog radio channel due to the refraction and multiple propagation that causes time dispersion in the digital radio channel.

The present invention also solves the problem by designing a mobile radio system to be lower than the time-distributed maximum time-dispersion in a particular radio channel. Briefly describing the present invention, a digital radio signal channel can be used by installing an equalizer so as to reduce the maximum time dispersion as the integer symbol time interval is reduced, and instantaneous movement from the digital radio channel to the analog radio channel is provided by the equalizer. When this is greater than the maximum time variance. Thus, it is moved to an available analog radio channel. If there are enough digital radio channels available, the digital radio channel is selected. In such a case, the shift of the available analog radio channel is made only when there is no digital radio channel available enough. If there are enough digital radio channels available, the digital radio channel cannot be moved.

The radio propagation characteristics of the digital radio channel used should be investigated to know when the time dispersion occurred in the digital radio channel used. This investigation is done by signal level and preference error frequency. This method is provided by Italtel in a pan-European GSM system and is published in GSM / WP2 doc 17/88, registered as a GSM article. Methods for measuring and transmitting bit error ratio information are described below (see: Italtel Ericussion and US digital cullular standard in a paper forwarded to the TIA Technical Subcommittee, TR-45 Digital Cellular Standars, August 29, 1989). California).

Estimation of the signal level and preference error frequency is preferably performed in a mobile station which reports the estimation to the base station. This corresponds to the GSM standard TIA in digital Cellular mobile radio systems.

Instead of directly estimating time dispersion with a bit error rate and signal level, the time dispersion may be estimated using a synchronizing word and a reception identifier transmitted in a digital radio channel. This direct measurement method is based on the bit synchronization timing of the A. Baier, G. Heinrich U. Wellens, N. Viterbi equalizer for TDMA digital mobile radio systems in Philadelphia, PA, June 15-17, 1988. It is based on the 38th IEEE Vehicle Technology Conference on Sensing.

Continuous estimation of other digital radio signals is currently using the mobile radio system. As a result of estimating the propagation characteristics of the used digital radio channel, if the used digital radio channel is insufficient, the movable digital radio channels have propagation characteristics.

In order to increase the continuous movement in the analog radio channel, propagation characteristics of the intended analog radio channel should be estimated. That is, the signal must be estimated for the expected signal level and the noise ratio of the channel. If this is difficult to estimate at the mobile station, it is estimated at the base station.

Since the digital radio channel is made in a fixed part where the analog radio channel is known, and the time dispersion estimation and radio signal characteristics are also made in the system, the known switching signal procedure of the analog radio channel system is used. The mobile radio system, which acts as a mobile switching procedure, measures or estimates the time variance of the digital radio channel to the analog radio channel.

[Detailed Description of Examples]

1 illustrates ten cells C1 to C10 in a cell wireless mobile system. The method according to the invention is carried out in a cell radio system comprising at least ten cells. However, ten cells are satisfactory for explaining the present invention.

Each cell C1 to C10 exists at each base station B1 to B10. 1 illustrates a base station in the cell center and has an omni-directional antenna. Base stations of adjacent cells are located near each other in the snow boundary and have a conventional directional antenna.

In addition, Fig. 1 illustrates ten mobile stations M1 to M10 in a cell, and the mobile stations move their respective cells. The method according to the invention is carried out in a cell radio system comprising more than ten cells. In particular, the number of mobile stations is ten times the number of base stations. However, only ten mobile stations can fully explain the present invention.

Figure 1 also has a mobile switching center MSC. The mobile switching center illustrated in FIG. 1 is connected to ten base stations by cable. The mobile switching center is cabled to a fixed public switched telephone network with an Integrated Services Digital Network (ISDN) facility. The mobile switching center connects all cables to the base station and to the fixed network (not shown). The illustrated mobile switching center is connected to another mobile switching cabled to another base station in addition to that illustrated in FIG. Instead of cables, other means may be used to connect to the mobile switching center, ie the radio link.

The cellular mobile radio system illustrated in FIG. 1 includes a plurality of radio channels for communication, and sets up digitized voice, which is analog digital information, and digital data, which is pure digital information. When this is used, cell phones connect between the mobile station and another mobile station using a telephone or terminal of a fixed network connected to the mobile radio system, a communication channel in the system or another system.

Thus, this connection invokes two conversations and a data communication channel of computer exchange data.

Figure 2 illustrates a number of very simple and up to RCH1 to RCH2N in the frequency band. The first group of radio channels RCH1 to RCHN is used in cell-based mobile radio systems for transmitting radio signals from a base station to a mobile station. The second group of radio channels RCHN + 1 to RCHN2 is used in cell-based mobile radio systems for transmitting radio signals from mobile stations to base stations.

Some radio channels are used as control channels. Each base station has one or more control channels. In general, rather than transmitting information about the connection of the control channel, it is maintained by the established connection and the switching of the established connection used to detect and control movement when connected. 3 illustrates how much the radio channel RCHf full time is used as the control channel CCHk and how the radio channel RCHg full time is used as the control channel CCHr.

Some wireless channels are used as analog communication channels, and in general analog communication is used for a connection for exchanging analog information, for example, for a telephone call in which two people talk to each other. In general, one analog communication channel is required to make this connection. When the wireless channel is used as an analog communication channel, the connection information is transmitted as an analog modulated radio signal. Connection information is added to the analog communication channel and used as association information. 3 illustrates how the radio channel RCHa was used for the analog communication channel ACHi all the time, and how much the RCHb was used for the analog communication channel ACHv all the time. In general, each base station has at least one radio channel used for an analog communication channel.

Some channels are used as digital communication channels. In general, digital communication channels are used for connections that switch to data or digitalized voice that is digital or digitalized information. The radio channel used as the digital communication channel is divided into timeslots, which are organized into frames. Since timeslots are assigned to digital communication channels, the digital channels are divided in time division multiplexes. 3 illustrates a radio channel RCHc with three timeslots in each frame F. FIG. The first timeslot is assigned to digital communication channel DCH4, the second timeslot is assigned to digital communication channel DCH5, and the third timeslot is assigned to digital communication channel DCH6. Figure 3 also illustrates how radio channel RCHD was used for three digital communication channels DCH7, DCH8 and DCH9.

In FIG. 3, frame F of radio channels RCHc and RCHd has three timeslots. Depending on the required bandwidth of the digital communication channel, the number of slots in the frame can be reduced to two or more. If the digital communication channel is used for the connection to switch the digitalized voice, six slots are degraded in the voice characteristics when the radio bandwidth is 30KHz.

A base station or mobile station on a radio channel used as a digital communication channel transmits a timeslot identifier code with a radio signal in all timeslots used for the connection. On a particular radio channel, RCHc, the timeslot identifier code is specific to each timeslot. Thus, timeslot identifier code TI1 is transmitted in the first timeslot of radio channel RCHc assigned to digital communication channel DCH4. The timeslot identifier code TI2 is transmitted in a second timeslot of the radio channel RCHC assigned to the digital communication channel DCH5. The timeslot identifier code TI3 is then transmitted to a third timeslot assigned to the digital information channel DCH6.

The same timeslot identifier codes are used on more than one radio channel, all possible radio channels. 3 illustrates how much time has been transmitted in the timeslot identifier, the first timeslot of the radio channel RCHd allocated to the digital information channel DCH7 of TI1. The timeslot identifier code TI2 is transmitted in a second timeslot of the radio channel RCHd assigned to the digital information channel DCH8. The timeslot identifier code TI3 is transmitted in the third timeslot of the radio channel RCHd assigned to the digital information channel DCH9. Thus, the timeslot identifier code does not identify the channel, but rather the timeslot of the frame. Since the channel with three slot frames F has one set of timeslot identifiers TI1 through TI3, and the channel with six slot frames F has a set of TI4 through TI9s, the timeslot identifier can also be found in the frame of the radio channel. Multiple slots must be indicated.

Further, a digital voice color code having a radio signal is transmitted in at least respective timeslots used for connection of the mobile station and the base station over the radio channel used as the digital radio channel. The same digital voice color code on a particular radio channel transmits the radio signal according to its time slot. 3 illustrates the transmission of the same digital voice color code VC1 in all timeslots of the radio channel RCHc. In general, the same digital voice color code is used for all radio channels in a particular base station. In other words, the digital voice color code VC1 is used for all radio channels at the base station BS1.

Some adjacent base stations are used for the same digital voice color code. That is, the base stations B2, B6 and B7 are used for the same digital voice color code only for the base station BS1. Different base stations are used for different digital voice color codes. That is, all of the base stations B4, B5 and B10 use the digital voice color code VC4. Another base station uses another digital voice color code. That is, the digital voice color code VC7 of the base stations B3 and B8 is used.

Radio signals of radio channels using digital communication channels in time division multiplex are transmitted in bursts. 4 illustrates a bus in a timeslot separated by a guide space from the end of a preceding burst and the beginning of a trailing burst in an adjacent timeslot.

The transmitted burst includes a timeslot identifier (T1), a digital voice color code (VC), and generally also includes information transmitted from other parts of the channel assistant information for control or sensing.

In the prior art, it is well known that reception synchronization is required in time-distributed multiple access radio switching systems. To achieve this, a form or sync word is sent in each burst, and a special frame sync word is sent from a master or base station to a slave or mobile station. Preferably, the time slot identifier code according to the present invention is installed and used in the transmitter to achieve synchronization of the receiver. In this method, selecting a time slot identifier does not mean that the timeslot identifier code according to the invention must be installed in the bits provided for the timeslot identifier. In principle, there are a number of binary binary bitwords, i.e. 26 bitwords. And this is used for each sync word. In the present invention, one unique timeslot identifier and a sync word are needed for timeslots of frames on the channel. In order to synchronize with timeslot identification, the timeslot identifier codewords must be selected with their respective correlations minus their correlations in phase.

The first timeslot identifier code for matching the first timeslot of the frame and synchronizing the receiver to the transmitter according to the present invention should be arranged in low correlation to the match code outside the phase and high correlation to the match code inside the phase. It must be arranged as. The second timeslot identifier code used to match the second timeslot of the frame and synchronize the receiver to the transmitter should be arranged out of phase with a low correlation to the matching code outside the phase and inside the phase with a high phase relationship to the matching code. Should be. In addition, all timeslots used on the channel should be arranged in low correlation to the coincidence code outside the phase and in high phase relation to the coincidence code inside the phase. Any timeslot identifier code used on a channel must also be arranged in a low correlation to the phase relationship, ie different timeslot identifier codes used on the channel, regardless of the inner phase or the outer phase.

Since timeslot identifier codes are given in the prior art, it is possible to select timeslot identifier codes without creative activity. However, the next eight 26-bit words, not introduced in the art, are given by way of example a possible timeslot identifier code for eight slot frames.

Code in timeslot 1:

(0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1 ,One)

Code in timeslot 2:

(0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1 ,One)

Code in timeslot 3:

(0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1 ,0)

Code in timeslot 4:

(0, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 1 ,0)

Code in timeslot 5:

(0, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1,1 )

Code in timeslot 6:

(0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1 ,0)

Code in timeslot 7:

(1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1 ,One)

Code in timeslot 8:

(1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0 ,0)

If it is smaller than eight timeslots of a frame in a radio channel, then a given codeword is also used which is smaller than eight. However, if there are only three timeslots of a frame, it is advantageous to use a given code.

Of course, it is convenient to use a binary timeslot identifier code (26 bits or more). Longer codewords have some advantages, but they have the disadvantage of taking up more space in the burst.

Advanced Mobile Phone Service System AMPS has a supervisory response tone AST transmitted over an analog communication channel. The reason for transmitting the SAT in the AMPS is that an entity transmitted by a mobile wireless communication network limited to interference with respect to a receiving entity base station (identifying a mobile station or the transmitter does not continuously identify transmission and excludes an entity of a transmitter). For purposes of the present invention, the digital channel code in the Celluler mobile radio system is partly identical to the SAT of the AMPS, and there are three false SATs in the AMPS. There are three or more false digital voice color codes, which signify a discontinuous transmission, so that cells of the same radio channel with the same color code are located at sufficient distance from each other to protect multiple digital color codes. Prevents inter-channel interference, and discontinuous transmission is a noise when used as a disturbing signal of another station. To this end, it seems sufficient for the eleven bit color codes to be normal, but the longer the color code, the longer the connection and switching procedure, considering the possible load on the control channel, eight bits A digital voice code seems to be a good fit A digital voice channel code is a binary word with eight bits, theoretically 256 false voice color codes.

Since each digital voice color code requires space in bursts, the space available for voice or data on the connection must be reduced. However, the performance of the next voice code does not require bits for the digital voice code in bursts over the digital communication channel.

On the transmitting side, the digital voice color code codes the channel and then adds an error detection field to the two bit modules without error correction in the information of the burst portion. The bursts of timeslots on the receiving side are checked. This check is detected by adding two additional bits to a well-known digital voice color code module before protecting the channel and detecting errors on the transmitting side. If no error occurs after adding two pieces of information to the digital voice color mode module, the portion of the burst is transmitted at the expected transmitter and is not interfered.

FIG. 5 illustrates a base station in a mobile channel according to FIGS. 2-4 and a cell flow according to FIG. The base station makes transmission and reception on a plurality of radio channels used for digital communication channels, analog communication channels, and control channels. 5 does not illustrate all base station equipment, only all channels. Generally, a base station includes a channel, in particular an analog communication channel, a device for power supply, etc., but the illustrated equipment can fully understand the present invention.

The base station is connected to the mobile switching center by six trunks. The first input trunk of the digital communication channel is connected to the digital trunk demultiplexer and interface DMU-D, and the second input trunk of the analog communication channel is connected to the analog trunk interface and demultiplexer DMU-A. The third input trunk of the control channel and base station control information is connected to the trunk interface and the control information demultiplexer DMU-C. The first output trunk of the digital communication channel is connected to the digital multiplexer and trunk interface MUX-D, and the second output trunk of the analog communication channel is connected to the analog multiplexer and interface MUX-A. The third output trunk of the control channel and base station information is connected to the control information multiplexer and the trunk interface MUX-C.

For each of the output radio channels used for the digital communication channel, the base station is connected to the digital analog channel coding means DCC and interface DMU-D connected to the digital trunk demultiplexer, two module adding means M2A, burst generating means BG, modulator means M0D and antennas. Each of the connected power amplification means PA and the like. Two such output radio channels allocate two module adding means, digital voice color code means VCS, connected to M2A. Two such output radio channels assign timeslot identifier code means TIS connected to the burst generator BG.

For each of the output radio channels used for the analog communication channel, the base station comprises analog transmission channel processing means ATC and demultiplexer DMU-A connected to the analog trunk interface, modulator means M0D and power amplification means PA connected to the antenna.

For each of the output radio channels used for the control channel, the base station comprises an output control channel processing means CTC and a control information demultiplexer DMU-C connected to the trunk interface, a modulator means M0D and a power amplification means PA connected to the antenna.

For each of the input radio channels used in the digital communication channel, the base station shall be equipped with a radio receiver means REC, radio signal strength or level measurement means SLM, analog / digital conversion means A / D, multiple equalizer and burst synchronization, time Slot recognition and automatic frequency control means EQ-AFC, two module addition means M2A, digital channel decoder means DCD connected to the digital multiplexer and trunk interface MUX-D.

The two input radio channels used for digital communication allocate the digital voice color code means VCS connected to the two module addition means. In addition, two such input radio channels assign a digital channel bit error measuring means BEM connected to the digital channel decoder DCD.

For each of the input radio channels used for the analog communication channel, the base station selects the radio receiver means REC, the radio signal strength or level measurement means SLM connected to the antenna, the input analog channel processing means ARC connected to the analog multiplexer, and the trunk interface MUX-A. Include. For each of the input radio channels used for the control channel, the base station includes a radio receiver means REC coupled to the antenna, a radio signal strength or level measurement means SLM, an input control channel processing means CRC coupled to the control information multiplexer, and a trunk interface MUX-C. do.

All transformer means and radio receiver means are connected to the frequency synthesizer means FS. The frequency synthesizer means is controlled by the central processing unit CP. The CP controls each of the two connected DCC, VCS, BG, EQ-AFC, DCD and one connected BEM, ATC, ARC, CTC, CRC, and MUX-C. Preferably the central processing unit CP is not only a processing unit at the base station, but also a processing unit including ATC, ARC, CTC, CRC and EQ-AFC.

The base station according to FIG. 5 is intended to communicate not only to mobile stations having equipment for analog communication channels but also to control channels. In addition, the base station is intended to communicate not only to the mobile station having the equipment for the digital communication channel but also to the control channel. It is also intended to communicate with base station analog and digital communication channels, as well as with dual-mode mobile stations that wish to communicate on the channel.

Mobile stations designed only as analog communication channels are well described in the art and operate according to the AMPS standard. Moreover, the method according to the invention is to provide a mobile station with means for communication over digital and analog radio channels. Thus, it is not necessary to intervene a mobile station that is designed only with analog radio channels and that is designed solely for operation. Thus, there is no need to describe a dual mode mobile station which is used only for communication for analog radio channels and control channels.

FIG. 6 illustrates the Celluller radio system according to FIG. 1 in communication with the base station according to FIG. 5 for the radio channel according to FIGS. 2-4. Each portion illustrates having communication on a digital radio channel. A dual mode mobile station using analog and digital radio channels, in addition to the means illustrated in FIG. 6, includes a first analog signal processing means connected to a microphone, a radio receiver IF stage and a second analog signal processing means connected to a speaker. The first and second analog signal processing means are represented by one block and controlled by the microprocessor.

The mobile station is connected to digital voice code means for encoding analog and voice or sound into a binary code, preferably having a bandwidth of 7-8 Hz, which is less than 11 kHz. In the voice coding means, the voice coding means is connected to the channel coding means for error protection coding interposed between the digital information in the voice coder. The channel coder is connected to two adders for modules that add digital information to the digital note color code at the channel coder. The two module adding means are connected to a burst generator which gathers the information transmitted in the burst and aligns the information including the timeslot identifier code into the appropriate burst. When a mobile station is used to establish a data transfer or connection for a connection, the burst generator controls the information of the burst without generating data or digitizing the voice. This information is supplied from the keyboard via the microprocessor and channel code or directly from the microprocessor. The modulator is connected to a burst generator that receives digital information and amplifies the power amplifier by modulating the information over a radio frequency in a frequency synthesizer. The power amplifier is connected to the antenna via a duplexer and controlled at the microprocessor.

The mobile station also includes a radio receiver, radio signal or level means and analog / digital conversion means connected to the duplexer. The radio receiver includes filters, RF and IF stages with decoding capabilities. The digital communication channel and the means for equalizing the automatic frequency control and the automatic gain control are connected to the inputs of the radio receiver and the two module adders. The two module adders include two digital voice color modules in the digital information from the equalizer. The outputs of the two module adders are connected to a channel decoder that detects errors and corrects digital information in the two module adders. Means for converting digital information into analog information or voice are connected to a channel decoder and a speaker.

If the mobile station changes the radio channel used for the base station to a control channel, some of the illustrated equipment of the mobile station does not use the channel and the voice decoder. When control and sensing information is transmitted from a base station in a control channel according to the AMPS standard, the microprocessor receives and interprets the signal from the analog / digital converter.

Without time slot identifiers, digital voice color codes, and means for guiding, recognizing, and eliminating the flow of information, the mobile radio signal according to FIG. 6 operates on a time division multiplexer digital communication channel, which is Ericsson Review 1987 No . Similar to digital mobile radio stations covered by 3 or GSM standards.

Therefore, it is not necessary to describe the detailed operation of the various means here. For the timeslot identifier code and the digital color code, the mobile station includes means for storing all possible timeslot identifier codes and digital voice color codes used to communicate with the base station. The microprocessor receives instructions from the base station that encodes for use in a particular connection, reads the code from memory and supplies two module adders and burst generators with appropriate timeslot identifier codes and digital voice color codes.

Synchronization and re-recognition of the timeslot identifier when the radio signal is received at the base station is performed in the equalizer together with the microprocessor. The measurement of bit errors for established connections is performed in the channel decoder along with the microprocessor. Equalizers, synchronization methods and bit error measurements are well known in the art. Therefore, it is not necessary to describe in detail their means and methods of implementation here. However, for those who are not familiar with the art, it will be briefly described in connection with FIGS. 6 and 7.

In this embodiment, the portion of the digital information transmitted in the digital radio channel is protected by the error correction code. For example, two GSM and TIA systems use a 20ms speech block with part of the speech code output bits protected by an error correction code. Error correction is applied when the voice coder activates the block.

Since a difference occurs between the information emitting the channel code of the transmitter and the information received by the receiver decoder, a bit error ratio BER of a radio signal including transmission and reception means occurs at the base station and the mobile station. This is illustrated in the left part of FIG. Estimation of the bit error ratio is made by re-encoding the decoded data at the receiver and compares this bit flow with the output of the channel decoder of the receiver. This is illustrated in the right part of FIG. An additional channel code is used for this purpose and in FIG. 6 the additional channel coder is installed in the receiving portion of the mobile radio station. Additional channel coding means are of course installed in the receiving portion of the base station according to FIG. The base station uses the central processing unit and the mobile station's microprocessor to compare the corresponding digital codes according to FIG.

If received and the channel decoder corrects all bit errors in a block of n bits, the bit comparison of the recoded data and the received data is equal to a number of bit errors in the block of n bits. Therefore, in this case, the estimated number of bit errors is equal to the true value of the bit error. In an n-bit block, the bit error ratio is a number of bit differences divided by n.

If the channel decoder of the receiver cannot reproduce the transmitted n bits, that is, if the channel decoder makes an error, the estimated bit error ratio is not substantially equal to the error ratio. The difference between the estimated cost and the real cost is represented by the measured noise term. The system is intended to operate with radio link characteristics where most blocks are calibrated by the channel decoder. Otherwise, the measurement noise is limited because the speech characteristics cannot be understood. If the radio link characteristic is too low, almost all blocks cannot be corrected by the channel decoder, so the output of the decoder is lower than the random form of low communication of the received block. This occurs immediately if the amount of time dispersion is greater than the equalizer can adjust. Importantly, every second bit comparison will point out a bit error due to the difference between the two blocks with non-communication by allowing the bit air estimation to make a correction decision of very low radio channel characteristics. Therefore, the bit error rate will be estimated at 50%.

In summary, regardless of radio link characteristics, this method will illustrate the characteristics of the radio link at the receiver in the bit error estimation term.

The procedure of the connection in the Celluller mobile radio system according to FIG. 1 having a base station according to FIG. 5 and a mobile station according to FIG. 6 is the same as the corresponding procedure in AMPS when the channel used is an analog communication channel. However, if the channel used for the connection is a digital communication channel according to FIGS. 3 and 4, the base station transmits information to the mobile station not only in the radio channel but also in the digital color code using timeslots. During the procedure, the base station transmits information to the mobile station over a plurality of radio channels with the signal strength measured by the mobile station. In general, a plurality of radio channels are radio channels to be used as channels beside adjacent bases / cells. During the connection according to the mobile station's motion and other conditions a new number of radio channels are selected and corresponding and information is transmitted from the base station to the mobile station. During a connection using a digital communication channel, the mobile station measures a signal of signal strength over a given number of radio channels. This measurement is taken while the timeslot is not used by the digital communication channel. The mobile station also measures the strength of the signal on the digital communication channel used for the established connection and the bit error ratio over the established connection. The mobile station doubles the measurement result to the base station.

In addition to signal strength and bit error ratio, the mobile station estimates time variance over the digital radio channel using the timeslot identifier code and equalizer described above. The mobile station transmits a signal level or bit error ratio measurement result to the base station.

The base station also measures signal strength over the digital communication channel used for the established connection and bit error ratio over the established connection. The base station measures time variance over an input wireless channel and / or used as a digital communication channel. This is measured using a timeslot identifier code and equalizer, which will be explained later. The base station processes and analyzes the results of the measurements made by the support station, time variance estimates and / or mobile station estimates and / or time variance estimates, and compares the criteria for channel switching. According to the results and criteria, if the transmission of another base station is desired, the base station transmits information to the mobile switching center indicating one or more target base stations to communicate with the mobile station.

The mobile switching center measures the strength of the signal to the target base station S on the radio channel of the timeslot used by the mobile station for the established connection. The mobile switching center also transmits information to the target base station S on the digital color code used by the mobile station.

The target base station S tunes the receiver to the radio channel indicated by the mobile switching center and uses the time slot identifier of the time slot for burst synchronization. The target base station checks the appearance of the digital color code indicated by the mobile switching code and measures the signal strength of the burst signal provided to correct the digital color code. The target base station transmits the measurement result of the signal strength to the mobile switching center. The target base station also sends the check results to the mobile switching center for the appearance of the digital color code. In other words, it transmits whether the digital voice color code appears in the burst of the timeslot of the radio channel.

The mobile switching center determines whether the transmission of the target base station accepts the signal strength measurement result of the target base station according to the traffic load.

If the mobile switching code center decides what other base stations and digital radio channels should do, it will base and target information on the new radio channel, new timeslots, new voice color codes used by the mobile station in the post-switch connection, and after the switch. Transmit a new radio signal used by the connected target base station.

The base station sends information around the two new radio channels, new timeslots, and new digital color codes to the mobile station. After receiving this information, the mobile station switches the new radio channel used for connection by the target base station and observes the new timeslot identifier code in the received signal over the radio channel. The mobile station uses a new timeslot identifier code in the received signal for burst synchronization. After switching and synchronizing the transmitters of the new radio channel, the mobile station begins to transmit a burst in a new time slot over the new radio channel.

The target base station switches the receiver to the new channel used to connect next to the mobile station and observes the new timeslot identifier code. The target base station uses the timeslot identifier code for synchronization. The target base station then converts the new digital color code in the signal of the new timeslot of the new channel. If the target base station is equal to the new digital color code in the bursts of the new timeslot of the new radio channel, this is reported in the mobile switching code. The mobile switching center then interprets the channel hand off continuously. After successive switching, the target base station with the base station transmits the information to the particular mobile station over the new multiple radio channels with the signal strength measured by the mobile station.

In the embodiment of the switching method described above, the base station and the mobile station use the same timeslot identifier and the same digital voice color code. However, different timeslot identifiers must be used at base stations and mobile stations of particular access.

In a specific embodiment of the switching method described above, the mobile station measures signaling on the radio channel controlled by the base station. However, especially when there is no radio channel used as a control channel by the base station, the mobile station measures the signal strength over the radio channel used as the digital communication channel by the base station.

If the base station and the target base station are the same, the inter-cell transmission procedure from the digital radio channel to the analog radio channel of the same base station is less complicated than the switching procedure described above. According to the results and regulations, the base station transmits information to the mobile switching center when switching from the digital radio channel to the analog radio channel is desired. After transmitting the information to the mobile switching center, the base station is performed as a general procedure of the system for inter-cell switching in a new radio channel, which includes transmitting information to the mobile station using the new radio channel. In carrying out the present invention, this procedure also utilizes the transition from digital to analog channels due to time variance. Therefore, it is not necessary to describe all such procedures here. It can be seen that there is no need to transmit information on the timeslot identifier code or digital voice color code from the base station to the mobile station instead of transmitting the supervisory sound tone or similar number of information from the base station to the mobile station.

The switching procedure from the digital channel of one base station to the analog channel of another base station is more complicated than the intercell switching procedure since it has more than one base station. However, a new base station switching system and a new analog channel procedure are used, which include values for transmitting information to the new base station and the base station on the new analog channel. This procedure is also used if the invention is carried out in a mobile wireless system with analog channel switching in accordance with the AMPS standard. Such switching procedures are well known in the art if the present invention is carried out in a system having a different procedure switching. Those who are not familiar with the description of the analog channel switching procedure are encouraged to learn the specifications of the system and the specifications of the NMT and AMPS systems that are patented in the supplementary and switching technologies of the present invention.

The mobile cell system according to FIG. 1 is centralized in the mobile station switching sensor while not centralized in the mobile station. In non-centralized systems, the function of the mobile switching station is prepared and executed by the target base station during the transition.

6 and 8 illustrate a method of estimating and determining the time dispersion when it occurs too large.

In Figure 6, the signal from the A / D converter is sampled over J times per unit time. The received signal in the equalizer is correlated with a partially stored timeslot identifier. In this method the channel impulse response of the estimated Y (t) is calculated at the equalizer and processed and equalized at the central processing unit. In Figure 8 the absolute value of Y (t) is expressed as a function of time. The distance between adjacent displayed values of Y (t) represents the symbol (bit) time T divided by j. The process of estimating the impulse response is detailed in bit synchronization and timing sensitivity in adaptive Viterbi Equalizers for narrow-band TDMA mobile radio systems.

The equalizer correlates the received signal with the timeslot identifier TSID for the span wt (hereinafter referred to as the measurement window) illustrated in FIG. The length of the measurement window represents the amount of time dispersion that the equalizer can control. That is, the energy in the measurement window, which plays a positive role in demodulation / bit detection, represents the energy outside the window, which serves as an interference signal. The length of the grinding window is a parameter in the manufacture of the equalizer. Equalizers with long windows can adjust many time variances, but they are more complex and consume more power.

The equalizer moves the grinding window according to the impulse response, calculates the impulse energy and positions the window according to the impulse response where the partial energy c in the window is maximum. In Figure 8, the impulse response of the inner part of the window is indicated by hatching. The maximum energy here means that the impulse energy r outside the measurement window is minimal. This is described in more detail with reference to the description mentioned for the position of the movable window. Estimation of the impulse response is a characteristic of the equalizer. As the equalizer algorithm is used, the impulse response is estimated at each burst as described above and renewed for the duration of the burst. Thus, the central processing unit obtains the amount of useful energy c and interference energy r from the equalizer in every burst at least once in every burst. The processing unit of the receiver can average the respective c and r values for n bursts, thereby reducing the effects of estimation errors and reducing various short times of radio propagation characteristics.

Average amounts of c and r are denoted by C and R, respectively. Since C is expressed as useful energy and R as disturbance energy, the C / R ratio represents the ability to synchronize to reproduce the transmitted data. However, this C / R ratio is similar to the S / N ratio used for telephony.

If the C / R ratio is low, the bit error ratio is high. If the time dispersion is so large that the transmitted voice signal or data cannot be reproduced, it is necessary to make a processing device for comparing the C / R and the threshold value to be used to determine the specification. Thus, if C / R is less than t, the processor determines a very large time division. Of course, the described time variance estimation method on the digital radio channel is done at the base station and the mobile station.

The present invention does not restrict the use of a particular method and the decision to switch to another channel is based on the time variance estimation method.

Claims (11)

A multichannel mobile radio system comprising a base station and a mobile station for transmitting information digitally to a digital radio channel using a digitally modulated radio channel and transmitting information to the analog radio channel using an analog modulated radio signal, the mobile station comprising: 8. An equalizer designed for maximum time dispersion of a digitally modulated radio signal, comprising: estimating the time dispersion of a digital radio channel available to a mobile radio station during connection; Compare the estimated time dispersion to the criteria for channel switching to an available analog radio channel and, when the estimated time dispersion equals the criteria for channel switching, transmit the information of the analog radio channel available to the mobile station and connect to the available analog radio channel. Channel switching; and maintaining a connection in a wireless mobile system having an analog radio channel and a digital radio channel. 2. The method of claim 1, wherein the time dispersion is indirectly estimated on the digital radio channel used by measuring the symbol error ratio and the signal level in the digital radio channel. How to maintain. 2. The digital radio channel according to claim 1, wherein the time dispersion of the digital radio channel is estimated by the base station when information is transmitted from the base station to the mobile station, and the estimate is reported from the mobile station to the base station. To maintain a connection in a wireless mobile system. The method of claim 1, wherein the time-distribution of the digital radio channel is used by the mobile station when transmitting information from the mobile station to the base station, and is estimated by the base station to maintain a connection in a wireless mobile system having an analog radio channel and a digital radio channel. Way. In a multi-channel mobile wireless system including a base station and a mobile station that transmits information using a digitally modulated radio signal on a digital radio channel and analog transmits information using an analog modulated radio signal on an analog radio channel. An equalizer designed for maximum time dispersion of a digitally modulated radio signal, comprising: estimating the time variance of the digital radio channel available to the mobile station during the connection and, if the analog radio channel is used for the mobile station, A method for maintaining connectivity to an analog radio channel and a digital mobile channel with digital radio channels, wherein the acid estimates a very large shift in the analog radio channel of the system that is considered to be sufficiently radioactive. 6. The method of claim 5, wherein the time dispersion of the digital radio channel is estimated to be available to the mobile station during continuous connection over the analog radio channel, wherein the time dispersion of the digital radio channel available at the mobile station is available in the analog radio channel. A method of maintaining a connection in a wireless mobile system having an analog radio channel and a digital radio channel, characterized by estimating a small transition to the channel. In a multi-channel mobile wireless system including a base station for transmitting information using a digitally modulated radio signal over a digital radio channel and transmitting information using an analog modulated radio signal over an analog radio channel, and a mobile station. The mobile station includes an equalizer designed for maximum time dispersion of a digitally modulated radio signal, wherein the mobile station estimates radio propagation characteristics of the first digital radio channel used by the mobile radio station during connection, and estimates the radio frequency characteristics of the first digital radio channel. When estimating that the radio wave characteristics are too weak, the radio station estimates radio wave characteristics of the second possible digital radio channel in the mobile station, and estimates that the radio wave characteristics of the first radio channel have good radio wave characteristics when the analog radio channel is used in the mobile station. When the analog radio channel is too weak to be estimated during operation The radio wave characteristics of the first radio channel are measured very weakly when other digital radio channels are insufficient, and the second digital radio channel is switched when the radio wave characteristics of the second radio channel are strongly estimated. A method of maintaining a connection in a wireless mobile system having an analog radio channel and a digital radio channel. 8. The radio propagation characteristics of one possible digital radio channel are estimated at the mobile station during continuous connection on the analog radio channel, and then the radio propagation characteristics of the digital radio channel available at the mobile station are available at the analog radio channel. A method of maintaining a connection in a wireless mobile system having an analog radio channel and a digital radio channel, comprising estimating a significant amount of switching to an existing digital radio channel. In a multi-channel mobile radio system including a base station and a mobile station that transmits information using a digitally modulated radio signal in a digital radio channel and digitally transmits information using an analog modulated radio signal over an analog radio channel, The mobile station includes an equalizer designed for maximum time dispersion of a digitally modulated radio signal, wherein the continuous connection is performed on the digital radio channel of the rugby to the signal level and symbol of the digital radio channel used by the mobile radio station during the continuous connection. If the mobile station estimates that the symbol error ratio of the possible digital radio channel is too large and the signal level on the available digital radio channel is too low, the radio station characteristic of the second possible digital radio channel is estimated at the mobile station, and the analog radio channel is estimated at the mobile station. Digital radio channel used when used The second digital radio channel when the symbol ratio of the radio channel used in a state where the preference error ratio is insufficient for other available digital radio channels in the mobile station with sufficient radio propagation characteristics is estimated too high and the radio wave characteristics of the second radio channel are also sufficiently estimated. A method for maintaining a connection in a wireless mobile system having an analog radio channel and a digital radio channel, wherein the switching is performed. 10. The radio propagation characteristics of one or more possible digital radio channels are estimated during continuous connection on an analog radio channel after switching, and the radio propagation characteristics of the digital radio channels available to the mobile station are sufficient for the available digital radio channels. A method for maintaining a connection in a wireless mobile system having an analog radio channel and a digital radio channel, characterized by estimating a good conversion. Multi-channel mobility including base station and mobile station for digitally transmitting information using digitally modulated radio signals over multiple digital radio channels and digitally transmitting information using analog modulated radio signals over multiple analog radio channels In a wireless system, the mobile station has an equalizer designed for maximum time variance of the digitally modulated radio signal, wherein the signal of the digital radio channel used by the mobile radio station for continuous connection and one or more other possible digital radio channels of the base station. Estimate the mobile station that has continuous access on the digital radio channel of the level and code error ratio, and estimate the second possible digital radio channel of the mobile station if the symbol error ratio of the used digital radio channel is too high and the signal level is too low on the used digital radio channel. And analog radio channels When used in a mobile station, when the symbol error ratio of the digital radio channel used exceeds the estimated analog radio channel performance switching first value such that the symbol error ratio of the digital radio channel used is sufficient, the higher estimated signal level and the very low estimated symbol error ratio are used. It is estimated that the symbol error ratio of the radio channel used in the absence of digital radio channel exceeded the first value and the other digital radio channel exceeded the second value, and the other symbol error ratio of the other radio channel was lower than the third value. A method of maintaining a connection in a wireless mobile system having an analog radio channel and a digital radio channel, characterized in that switching of different digital radio channels when performed.