JPH04320120A - Accessing method from moving apparatus to ground station system of mobile radio - Google Patents

Abstract

PURPOSE: To allow a mobile equipment to access a radio base station by using one or more time slots in a frame of the TDMA method. CONSTITUTION: A reservation field to send control information is provided for any one of among time slots 1-6, and in the case that the time slot is a digital control channel, the control information is not used for up-link and down-link communication. In order that a mobile equipment MS1 uses a reserved field for recognizing a sequential number of the time slot and to enable completion of transmission of an access message, the mobile equipment MS1 sends the control information to represent a time slot number for which the radio base station should make a reservation to the radio base station.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has a digital voice/traffic function, and a digital control channel has a voice/traffic function.
The present invention relates to a small zone mobile radiotelephone system capable of occupying time slots of the same radio channel as a traffic channel. More precisely, the invention relates to a method and a system for performing access functions on one digital control channel.

0002

BACKGROUND OF THE INVENTION The first public small zone mobile radio systems were generally analog based for the transmission of telephone calls or other analog information. These systems consisted of multiple radio channels for transmitting analog information between base radio stations and mobile devices by transmitting analog modulated radio signals. Recently, small zone digital mobile radio systems have been designed for public use.

0003

[Problems to be Solved by the Invention] A small zone type digital mobile radio system transmits digital information or digitized analog information between a base radio station and a mobile device by transmitting digitally modulated radio signals. It consists of digital channels. Small zone digital mobile radio systems have fundamental advantages over small zone analog radio systems.

One digital mobile radio system planned for use as a common system in many European countries is the GSM system. In European countries that already have small zone analog mobile radio systems,
The new digital GSM system is planned to be introduced as a new system that does not depend on any of the existing analog systems. GSM base radio stations and mobile devices are not designed to be compatible with existing systems, but they are designed for optimal performance from various aspects within and within the system itself. . Therefore, when designing the GSM system, there was a relatively large degree of freedom in selecting technical issues.

In areas where there is an existing small zone analog mobile radio system, it is preferable to cooperate with the existing small zone analog mobile radio system rather than introducing a new, unique small zone digital mobile radio system, such as the GSM system. It has been proposed to introduce a small zone digital mobile radio system designed to operate. In order to obtain a digital channel within the frequency band allocated to a small zone type mobile radio system, a large number of radio channels allocated to the current analog mobile radio system are recovered and converted into a small zone type digital mobile radio system. There have been proposals to use it for According to this design proposal for a digital mobile radio system, by using time division multiplexing, the same frequency band as one analog radio channel can be divided into three channels.
Or perhaps 6 digital channels could be occupied. Therefore, replacing some analog channels with time division multiplexed digital channels will increase the total number of channels.

The plan is to gradually introduce digital systems by increasing the number of digital traffic channels while decreasing the number of analog traffic channels in coexisting small zone systems. Traditionally used analog mobile stations can continue to use the remaining analog traffic channels. On the other hand, new digital mobiles can use new digital traffic channels. A dual-mode mobile station can use both the remaining analog traffic channel and the new digital traffic channel.

[0007] In conjunction with adding new digital traffic channels, a need will arise for new digital control channels. Most conventional dual-mode systems utilize existing dedicated frequency analog channels as control channels.

However, new all-digital systems will use digital control channels that occupy the same type of TDMA time slots as used for digital traffic channels.

[0009] This digital control channel has been used since early on in the European GSM system. In the GSM system, access is always performed in a single burst to minimize the occupation of channels dedicated to access. confirmation(
authentication) and encryption (cip
Any subsequent operations such as (hering) are performed on the other type of control channel allocated after it is actually accessed. The GSM system thus uses many different types of control channels, suggesting that it will be a fairly complex system. For this reason, as well as for good compatibility with existing North American dual-mode systems, it is desirable to use only one type of uplink control channel for all digital systems in the United States. The upshot of this is that in the United States, the control channel used for access must be able to handle verification or even other functions such as encryption that require one or more bursts within a single message. Became. The present invention solves a special problem that arises in connection with multi-burst access messages.

0010

SUMMARY OF THE INVENTION One of the objects of the present invention is to provide a procedure that can be used by a mobile station to access a ground station system via a digital control channel, but which Existing EIA/TI for digital traffic channels
The A-54 format must be used for digital control channels with only minor modifications. It performs the function of establishing access from the mobile device to the ground station system, so it uses the CDV of the traffic channel.
This is achieved by using the same format for both the traffic channel and the control channel, except that the CC and SACCH fields are used on the control channel.

Another object of the invention is to minimize the probability of collisions between access messages by providing a procedure for reserving for any burst following the first burst of an access message. That's true. This is achieved by including the following information in the uplink access burst: That is, either another time slot is to be reserved at a predefined time to continue the access message, or this burst will be the last burst in said message. Include information that indicates

Another object of the present invention is to enable multi-bursts while minimizing the access time for one burst access. This is achieved by having the mobile include in the first access burst whether this is the last burst or whether other bursts will follow. In the latter case, bursts are reserved after a predetermined interval, but many bursts are free for any other mobile that wants to access the ground station system.

Another object of the invention is to provide an access procedure that allows the access channel to a base radio station to be a full-rate channel or a half-rate channel, depending on the traffic capacity required on the control channel. It is to be. This is achieved by reserving uplink time slots at intervals greater than one frame for multibursts. As a result, the capacity of one full-rate access channel (the number of accesses per second) is twice the capacity of one half-rate channel, but the time required for an access message depends on whether the access channel is full-rate or half-rate. It doesn't matter what it is.

Another object of the present invention is to provide an access method in which the probability of multiple access is low. That is, it provides an access method that prevents one or more base radio stations from thinking that they are being accessed. This applies to DVCC if you encode/decode the cyclic redundancy check CRC in the same way as for the traffic channel.
(Digital Verification C
This is achieved by using a color code (digital matching color code). In other words, “clear” (e
xplicit) DVCC (message CDVC)
This "implicit" DVCC is still used, whereas the C field) is used for access procedures.

The two fields CDVCC and S
Each ACCH has 12 bits and both have 24 bits for uplink. The 24 bits are used in the digital access channel to carry one of two possible patterns for the uplink and one of two possible patterns for the downlink. This accomplishes two things. That is, first, in addition to the standardized 28-bit synchronization word, CDVCC and SACCH
Using two patterns of 24 bits of fields as synchronization words improves synchronization on the uplink and facilitates distinguishing control channels from traffic channels on the downlink. (other"(
2**24)-2'' pattern violates the rules. ) Second, if it is ``free'' or ``reserved'' (r
eserved) messages on the downlink;
By conveying a "reserve" or "do not reserve" message on the uplink as one of the two 24-bit patterns, it can be substantially misinterpreted.
Interpretation) is excluded.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows ten sub-zones C1 to C10 in one sub-zone mobile radio system. In practice, the methods and means according to the invention are implemented for small zone mobile radio systems comprised of much more than ten small zones. However, ten sub-zones are considered sufficient for purposes of explaining the invention. For each of the sub-zones C1 to C10, the same number of radio base stations B1 to B10 as the sub-zones.
There is. FIG. 1 shows a radio base station located near the center of a small zone and having an omnidirectional antenna. However, as is well known to engineers with ordinary knowledge of this technology,
The wireless base stations of adjacent small zones are located near the small zone boundaries and have directional antennas.

FIG. 1 also shows ten mobile stations M1 to M10 that can move within one sub-zone and from one sub-zone to another. In practice, the methods and means according to the invention are implemented for small zone mobile radio systems comprised of much more than ten mobile stations. In particular, the number of mobile devices is typically much greater than the number of wireless base stations. However, for purposes of explaining the invention, ten mobiles are considered sufficient. The system in Figure 1 also includes one mobile switching center (Mobile Switching Center).
nter:MSC). The mobile switching center is connected to all ten radio base stations shown by cables. The mobile switching center is also connected by cable to the fixed public telephone network or a similar fixed network with ISDN equipment. Cables from the mobile switching center to the radio base station and to the fixed network are not shown.

In addition to the illustrated mobile switching center, FIG.
There may also be other mobile switching centers connected by cables to other radio base stations than those shown. Instead of cables, other means can be used for communication from the radio base station to the mobile switching center, such as fixed radio links. The small zone mobile radio system shown in FIG. 1 is composed of a plurality of radio channels for communication. The system is designed for use with both analog information such as telephone calls, digitized analog information, digitized telephone calls, as well as pure digital information. According to this system, the word connection is used for a mobile device on a communication channel within the same system or another system, or a fixed telephone or terminal in the fixed network that is connected to this small zone mobile radio system. be done. Thus, a connection can be defined not only as a call that two people can speak to each other, but also as a data communication channel through which computers exchange data.

Referring to FIG. 2, an embodiment of a mobile station for use in a small zone mobile telephone system operative in accordance with the present invention is shown. Speechi Koda
chCoder (voice coder) 101 converts the analog signal generated by the handset into a bit data stream. This bit data stream is divided into data packages according to the TDMA principle. Fast Associated Con
trol CHannel) (FACCH) Generator 1
02 generates control and supervisory signal messages between the system and the mobile and messages between the mobile and the system. Each time a FACCH message is transmitted,
Exchange user frames (calls/data). Slow Associated C
(SACCH) generator 103 provides a continuous channel for exchanging signaling messages between the radio base station and the mobile device and between the mobile device and the radio base station. SA for each time slot in the message sequence
A fixed number of bits, for example 12 bits, are allocated to the CCH. Channel coder:
Channel encoder 104 is connected to speech coder 101, FACCH generator 102 and SACCH generator 103, respectively, for processing the input data for error detection and error correction purposes. Channel coder 1
The technique used in 04 is convolutional coding (co
cyclic redundancy check (CRC). Convolutional encoding protects the important data bits in the speech code and also
In RC, the perceptually significant bits in the frame of the speech coder, for example 12 bits, are used to compute the 7-bit test.

The selector 105 selects the speech coder 10
1 and a channel coder 104 associated with FACCH generator 102, respectively. Selector 105
is controlled by microprocessor controller 130 to alternate user information on a particular speech channel with system supervisory messages on FACCH at appropriate times. A two-burst interleaver 106 is coupled to the output of selector 105. The data sent by the mobile is interleaved into two separate time slots. The 260 data bits constituting one transmission word are divided into two equal parts and assigned to two consecutive time slots. The effects of Rayleigh fading will be reduced in this way. 2
The output of the burst interleaver 106 is modulo 2.
The data transmitted as input to the adder 107 is encrypted bit by bit using modulo 2 addition logic of the pseudo-random number bit stream.

The output of the channel coder 104 associated with the SACCH generator 103 is connected to a 22-burst interleaver 108 . The 22 burst interleaver 108 has 1 burst interleaver 108 in each of the 22 time slots.
Data to be transmitted is interleaved on the SACCH, which is composed of 2 bits of information. The 22 bursts
The interleaver 108 uses the diagonal reasoning principle (diagonal reasoning principle).
al principle), two SACCH messages are sent in parallel, so
The second message is moved 11 bursts from the first message. Additionally, the mobile station includes a sync word/DVCC generator 109 and a DVCC for the particular connection to provide the appropriate synchronization word and DVCC for the particular connection. The synchronization word is a 28-bit word used for time slot synchronization and identification. DVCC is an 8-bit code that is sent from the radio base station to the mobile station and from the mobile station to the radio base station to ensure that the correct channel is being decoded.

Burst generator 110 generates message bursts to be transmitted from the mobile station. burst generator 1
10 is a modulo-2 adder 107, a 22-burst interleaver 108, a synchronization word/DVCC generator 109, an equalizer 114, and a control channel message generator 13 that generates a channel-encoded control message.
Connected to the output of 2. Message burst is 260
bit data, 12 bits SACCH, 28 bits sync word, encoded 12 bits DVCC and 1
A total of 324 bits are integrated according to the timeslot format defined by standard EIA/TIA IS-54.

Under the control of microprocessor 130,
Two different types of message bursts are generated by burst generator 110: voice/traffic message bursts and control channel message bursts from control channel message generator 132. Control channel messages are sent to microprocessor 1
30 and sent on a digital control channel that has the same burst format as the traffic channel, but similar to speech data, if the SACCH is successfully generated within a voice/traffic burst, Messages are alternated with control information.

The transmission of a burst equivalent to one time slot is synchronized with the transmission of two other time slots and is adjusted by the timing provided by equalizer 114. Due to the time differences in the signals, adaptive equalization methods are employed to improve the signal quality. For more information on adaptive equalization methods, see February 2, 1989.
Serial number No. 7 was filed and assigned to the same assignee. 3
15,561 U.S. Patent Application No. 15,561. A correlator adapts to the timing of the received bitstream. Regarding frame timing, the wireless base station is the master and the mobile device is the slave. Equalizer 114 detects input timing and synchronizes burst generator 110. Equalizer 114 also examines the sync word and DVCC for identification purposes.

A 20 millisecond (ms) frame counter 111 and equalizer 114 are coupled to burst generator 110. The frame counter 111 is set to 2 by the mobile device.
Ciphering code used every 0ms
code) is updated once for each transmitted frame. It will be appreciated that according to this particular example, three time slots make up a frame. Encryption unit 112 is provided for generating encryption codes used in the mobile device. Pseudo-random number algorithms are preferably utilized. The encryption unit 112 is
Controlled by a unique key for each subscriber. The encryption unit 112 includes a sequencer that updates the encryption code.

The burst to be transmitted is transmitted by the burst generator 11.
0 and sent to an RF (radio frequency) modulator 122. The RF modulator 122 uses π/4-DQPSK (π/4
shifted, Differentially e
coded quadrature aphas
e Shift Keying: Modulate the carrier frequency by π/4 shift differential coding quadrature phase modulation). Using this modulation method indicates that the information is differentially encoded. That is, a 2-bit symbol is transmitted as four possible phase changes: ±π/4 and ±3π/4. The transmitter carrier frequency provided to RF modulator 122 is generated by transmitter frequency synthesizer 124 according to the selected transmission channel. The modulated carrier wave is amplified by a power amplifier 123 and then transmitted from an antenna. The carrier frequency RF power emission level is selected by command of microprocessor controller 130. The amplified signal passes through time switch 134 and reaches the antenna. This timing is synchronized with the transmission order by microprocessor controller 130. The amplified signal is passed to a time switch 134 and then reaches the antenna. The time switches are synchronized with the transmission order by microprocessor controller 130.

A receiver carrier frequency is generated by receiver frequency synthesizer 125 according to the selected receive channel. The input radio frequency signal is sent to receiver 126
and its strength is measured by a signal level meter 129. The received signal strength value is sent to microprocessor controller 130. An RF demodulator 127, which receives either the receive frequency signal from the receiver 126 or the receiver carrier frequency, demodulates the radio frequency carrier signal to generate an intermediate frequency. The intermediate frequency signal is demodulated by the IF demodulator 128 and restored to π/4-DQPSK modulated original digital information.

The digital information recovered by IF demodulator 128 is provided to equalizer 114. symbol detector 1
15 converts the 2-bit symbol format digital data received from equalizer 114 into a single-bit data stream. Symbol detector 115 sequentially produces three different types of output. Once the control channel message is sent to control channel message detector 133, the decoded channel and detected control channel information is provided to microprocessor controller 130. All speech data/FACCH data is provided to modulo-2 adder 107 and two-burst deinterleaver 116. Speech data/FACC
H data is reconstructed by these units by assembling and rearranging information from two consecutive frames of received data. Symbol detector 115 provides SACCH data to 22 burst deinterleaver 117. The 22-burst deinterleaver 117 reassembles and rearranges the SACCH data and spreads it over 22 consecutive frames.

Two-burst deinterleaver 116 has two channel decoders.
oder: channel decoder) 118 to provide speech data/FACCH data. Convolutionally encoded data is decoded using the inverse of the encoding principle described above. The received cyclic redundancy check (CRC) bits are examined to determine the presence of errors. Further F
The channel decoder for ACCH detects differences between the speech channel and FACCH information and directs decoding accordingly. speech decoder
h_decoder 119 processes the received speech data from channel decoder 118 according to a speech decoder algorithm (VSELP) and generates a received speech signal. The analog signal is finally refined to high quality using filtering techniques. Messages on the high speed control channel are detected by FACCH detector 120 and the information is transferred to microprocessor controller 130.

A 22-burst deinterleaver 117 is provided for another channel decoder 118. Messages on the slow control channel are detected by SACCH detector 121 and the information is forwarded to microprocessor controller 130. A microprocessor controller 130 controls mobile motion and radio base station communications, and also processes terminal keyboard input and display output 131. Decisions by microprocessor controller 130 are made based on received messages and measurements. A keyboard and display unit 131 allows information exchange between the user and the radio base station.

FIG. 3 shows an embodiment of a radio base station that can be used in a small zone mobile telephone system operating in accordance with the present invention. A wireless base station includes many components,
The structure and function of these components are substantially the same as for the components of the mobile device shown and described in FIG. Such identical components are labeled with the same reference numerals in FIG. 3 as used in the above drawings and description, but are distinguished by a prime sign "'".

However, there are slight differences between mobile devices and wireless base stations. For example, a wireless base station has two receiving antennas. For each of these antennas, one receiver 126', an RF demodulator 127' and an IF demodulator 1
There is 28'. Additionally, the radio base station does not include a user keyboard and display unit 131, such as those used in mobile devices. Another difference is that wireless base stations handle communications with multiple mobile devices. This results in three channel handlers each handling one of the three time slots of one frequency.
This can be understood from the fact that there are branches to (1), (2), and (3).

[0033] When power is applied to the mobile device, microprocessor controller 130 performs an initialization procedure. Initially, the service system parameters are retrieved to indicate that the desired system, eg wireline (B) or non-wireline (A), has been selected. The selection initiates scanning for dedicated control channels belonging to the desired system.

Receiver frequency synthesizer 125 is commanded by microprocessor controller 130 to generate a frequency corresponding to the first dedicated control channel. Once the frequency is stable, signal level meter 129 measures the signal strength and later microprocessor controller 130 stores the signal strength value. The same procedure is performed for the frequencies corresponding to the remaining dedicated control channels, which are ranked by microprocessor controller 130 based on their respective signal strengths. The receiver frequency synthesizer 125 is then commanded to tune to the frequency of the strongest signal strength level so that the mobile can attempt to synchronize to that channel.

[0035] The radio signal is captured by receiver 126;
It is demodulated by RF demodulator 127 and then by IF demodulator 128 according to the selected carrier frequency. The synchronization operation and primary analysis of the digital information of the radio signal is performed in equalizer 114. If the equalizer 114 can detect the synchronization word generator 109, the equalizer 114 locks to the time slot associated with the synchronization word. The mobile device is
It waits for system parameter overhead messages that are decoded by control channel message detector 133 and forwarded to microprocessor controller 130. This message includes system identification,
Information regarding protocol capabilities, the number of available paging channels (PCs), and their specific frequency allocations is included.

Under conditions where equalizer 114 is unable to confirm the synchronization word within a specified time, receiver frequency synthesizer 125 is commanded by microprocessor controller 130 to tune to the next strongest signal. Ru. If the mobile is unable to synchronize on the second selection, microprocessor controller 130 commands the desired system change from A to B, or vice versa. From now on, scanning of the dedicated control channel of the new desired system will begin.

When the mobile has completed receiving the system parameter overhead message, it can initiate a call in a manner similar to a dedicated control channel, ie, by measuring signal strength and selecting the frequency of the strongest signal. Channels are scanned. Synchronization for the paging channel then takes place.

[0038] Upon successful paging channel synchronization, the mobile station leaves the initialization procedure and enters idle mode. Idle mode is characterized by four states. These four states are controlled by the microprocessor controller 13.
0 and loops unless the system is accessed. It should be noted here that to ensure that the mobile is listening to the paging channel with the strongest signal strength, the paging channel must be scanned whenever the bit error rate on the current paging channel increases above a certain level. This means that this will be carried out.

The first state of idle mode is to continuously update the state of the mobile, eg, the number and location of existing access channels (ACs). This information is sent to the mobile in a System Parameter Overhead Message on the paging channel and forward digital control channel (Digital FORWARD).
Control Channel: DFOCC). This message is decoded within control channel message detector 133 and sent to microprocessor controller 130. Certain messages sent from the radio base station, among system parameter overhead messages, require corresponding action from the mobile station. For example, the rescan message is
The controller 130 is commanded to perform an initial setting procedure. To give another example, a registered mobile device confirmation message (registration ident) from a wireless base station
itymessage) allows the mobile to access the system and register according to the system access mode described below.

[0040] The second state of idle mode relates to a state in which the mobile attempts to adjust to paging messages sent by the radio base station. These mobile control messages sent on the DFOCC are decoded within the control channel message detector 133 and analyzed by the microprocessor controller 130. If the decoded number matches the mobile identification number, a connection to the radio base station is prepared in system access mode. The third state of idle mode involves listening to commands sent by the DFOCC from the radio base station. Therefore, the decoded commands, such as abbreviated alerts, are processed by the mobile device. The fourth state of idle mode involves the microprocessor controller 130 monitoring input from the keyboard 131 for user actions, such as initiating a call. Upon placing a call, the mobile leaves idle mode and enters system access mode.

One of the primary tasks in the mobile system access mode is for the mobile to generate access messages. The digital access channel (D
AC) is examined in a similar manner to measuring dedicated control channels, as described above. Each signal strength is ranked and the channel with the strongest signal is selected. Therefore, the transmitter frequency synthesizer 124
and the receiver frequency synthesizer 125 will be tuned to inform the radio base station about the type of access, e.g., call origination, call response, registration request or confirmation of registration command, so that a service request message is sent. Sent on the selected channel. After the transmission of this message is complete, the mobile station's amplifier 123 is powered down and the mobile station waits for a subsequent control message on the DFOCC. According to the type of access, the mobile receives appropriate messages from the radio base station.

If the access is an outgoing or paging, the mobile station is assigned a free traffic channel by the radio base station, and the mobile station switches to the traffic channel and leaves the system access mode. The mobile station then tunes transmitter frequency synthesizer 124 and receiver frequency synthesizer 125 to the selected traffic channel. Equalizer 114 then begins synchronization. A time alignment procedure is controlled by the radio base station based on delay time measurements of received signals performed at the radio base station. From this moment on, the exchange of messages between the radio base station and the mobile is carried out over the fast control channel FACC.
H and the slow control channel SACCH.

Microprocessor controller 130
Messages from FACCH generator 102 or S
Generated by an ACCH generator 103, the data is encoded into an error-proof code by a channel encoder 102. The FACCH data is time division multiplexed with the speech data in multiplexer 105 and interleaved over two bursts by two-burst interleaver 106. The data is then encrypted in unit 1.
It is encrypted in a modulo 2 adder 107 controlled by an encryption algorithm generated by 12. SACCH data is 22 burst interleaver 1
08 over 22 bursts and then fed to a burst generator 110 where S
The ACCH data is mixed with speech data, FACCH data, appropriate synchronization words, and DVCC from DVCC generator 109. RF modulator 122 is π/4-D
Modulate the bit pattern using QPSK. During the time to transmit a time slot, power amplifier 123 is activated and its power level is set to
Adjusted by 30.

[0044] Also, from the radio base station to the microprocessor
Control messages to controller 130 are also transferred via FACCH and SACCH. Speech decoder 119, FACCH detector 120 or SACCH
The symbol pattern of the bit data stream sent to detector 121 depends on the form of data used. Speech data and FACCH data are modulo 2.
Adder 107 and two-burst deinterleaver 11
It is decoded by 6. Channel decoder 118 detects bit errors and
Contact 30. SACCH data consists of 22 bursts.
After being deinterleaved over 22 bursts by the deinterleaver 117, the channel decoder 11
Error detection is performed at step 8.

Messages sent from the radio base station to the mobile typically include alarm instructions, requests to measure channel quality, call recovery, and busy channel switching instructions. Messages sent in the opposite direction are initiated by the mobile user. For example, a recovery command. The final recovery command means that the user ends the call and the mobile leaves control of the traffic channel and returns to its default operating mode.

FIGS. 4A, 4B and 4D are EIA/TIA
1 shows the structure of a digital channel defined in standard IS-54. FIG. 4A is a diagram illustrating the frame structure of a wireless channel. According to this example, one radio channel frame typically has a total of 1,944 bits or 972 bits.
It consists of six time slots containing six symbols. The frame length is 40 ms, and the data transmission rate is 25 frames per second. Each time slot is typically numbered from 1 to 6 and, as defined, each includes a 28-bit synchronization word.

FIGS. 4B and 4D illustrate the timeslot formats for mobile to ground station and ground station to mobile transmissions, respectively. Timeslot format is 260 bits reserved for data transmission, 12 bits of digital collation color code DVCC, slow control channel SACC
12 bits of H and synchronization and adjustment data (tr
28 bits of aining data (SYNC) are commonly included. The mobile to ground station timeslot format includes two 6-bit blocks for guard time (G) and ramp time (R) information. The earth station to mobile timeslot format includes blocks of 12 bits that are reserved for future use.

In half-rate format, each half-rate voice/traffic channel uses one time slot of each frame. This is 1, 2, 3, 4 in a row
1 with time slots numbered , 5, 6
It shows that the frame is composed of six half-rate traffic channels. In the full-rate format, each full-rate traffic channel uses two equally spaced time slots of the frame, eg, time slots 1 and 4, 2 and 5, or 3 and 6. In full rate format, the time slots are numbered 1, 2, 3, so the composition of a frame is 1, 2, 3, 1, 2, 3. For clarity of explanation, the present invention uses the full rate format in the examples shown below.

In order to carry out the method of the invention of accessing a ground station via a digital control channel, the format of the radio channel according to FIGS. 4B and 4D is changed to the format shown in FIGS. 4C and 4E. FIG. 4C shows the format of the time slots of the radio channel from the mobile device to the ground station when the channel is a digital control channel. In this case, if the radio channel is a traffic channel, the slow control channel SACCH and the digital matching color code DVC
There is no need for C. Instead, a reserved field R of 12+12=24 bits is used to transmit information for the ground station, as explained in detail with respect to FIGS. 6A and 6B.
ES is generated.

FIG. 4E shows the timeslot format of a radio channel from a ground station to a mobile device when the channel is a digital control channel. As mentioned above, there is no need for the slow control channel SACCH and the digital matching color code DVCC. 6A and 6B, the 12-bit SACCH becomes a first 12-bit reserved field RES1 and the DVCC becomes a second 12-bit reserved field RES2 for transmitting information to the mobile station.

FIG. 5 shows a standardized frame made up of control channels and traffic channels. In this example, when the system is in full rate mode, timeslots 1 and 4 are used as control channels and timeslots 2, 3, 5, and 6 are used as traffic channels. In the half-rate mode of transmission described with respect to FIG. 6B, only timeslot 1 of each frame is used as a control channel, and timeslots 2 through 6 are used as traffic channels. The multi-burst access method of the present invention for a mobile station in full rate mode will be described in detail with respect to FIG. 6A.

The first row a) of FIG. 6A shows a number of frames F1, F2, F2, each having time slots 1 to 6.
...indicates... Since this is full rate transmission, time slots 1 and 4 of each frame are control channels, and control messages such as access messages and confirmation messages can be freely exchanged. The frame structure in row a) includes a forward digital control channel DFOCC and a reverse digital control channel (DFOCC).
Digital Reverse Control
Channel: DRECC) and indicates the time slots of the frame for these channels of a particular carrier frequency. Line b) of FIG. 6A shows the time slot position of the reverse digital control channel DRECC, and line c) shows the time slot position of the forward digital control channel DFOCC. The position of the time slot for DRECC is a reference position, and the frame structure of row a) and the time slot coincide in time. The DRECC time slot is used for uplink transmission (mobile station MS → radio base station BS), and the DF
The OCC time slot is used for downlink transmission (radio base station BS→mobile station MS). The time slots used for transmitting calls are not shown. The DFOCC time slot is used for DR for a specified period of time for signal strength measurement, reversal time from transmit mode to receive mode, etc.
Separated from ECC time slots.

Initially, the mobile is in idle mode and the DFOC marked "F" in FIG. 6A, line c)
We are looking for control data (information) bursts in the C time slots. However, the method of the invention is not only limited to the above modes of operation, but also, as mentioned earlier,
It can also be used when the mobile performs tasks in subsequent access modes. In this way, the wireless base station can provide DF for one mobile device or all mobile devices.
OCC timeslot “F” and RES1 and/or
Alternatively, these mobiles transmit control messages in RES2, but these mobiles transmit messages on a particular DFOCC frequency channel, i.e., if time slot #1 of this frequency (or other frequencies f2, f3, etc.) is free. I am reading a DFOCC message indicating that Assume that a certain mobile station (MS1) captures the above message that time slot #1 is vacant (arrow A1). If the mobile station (MS1) wants to transmit to the radio base station, this free time slot is reserved for the mobile station (MS1) in the DRECC channel, and the reserved time slot is mark can be added.

When the mobile station (MS1) communicates in a reserved time slot (arrow A2), the mobile station (MS1) also requests that the next time slot #1 is always reserved. The radio base station sends a control message to the mobile with only a symbolic indication that this timeslot #1 must be reserved (arrow A3). Like this (F
7) Time slot R is reserved for the mobile station. Another mobile station (MS2) sends a frame (F
2), the empty time slot message F was captured, but
Time slot #1 of frame (F4) to the base station
The signal strength may be weak for communication. In this case, the mobile station with stronger signal strength (MS1
) wins and time slot #1 of frame (F7) is reserved for the mobile station (MS1).

[0055] In this way, the radio base station
), and the mobile station (MS1) receives the reserved time slot. In this example, the mobile station (MS1) is trying to transmit its own control message using three time slots, so the mobile station (MS1) is transmitting the frame (F
4), (F7) receives reserved time slot #1. After receiving the control message (arrow A5) from the radio base station, if the mobile station (MS1) uses the reserved time slot #1 of the frame (F10), the mobile station (MS1) sends the control message. Since three time slots are used including the last time slot, the mobile station (MS1) uses this reserved time slot as the final time slot. To this end, the mobile station (MS1) responds by sending a message indicating that the used time slot #1 is now free;
The last control message (arrow A6) is sent in the reservation field RES shown in FIG. 4C.

Further, FIG. 6A shows that shortly after the mobile station (MS1) accesses on the same carrier frequency f1, another mobile station (M
A case in which S2) accesses the system via a wireless base station is shown. While time slot #1 was assigned to the mobile station (MS1), time slot #1 of the same frame
4 is assigned to the mobile station (MS2). Assume that this mobile device is performing two-burst access to a wireless base station. Same procedure as mobile device (MS1), arrow (B1)
, (B2), is started, but the wireless base station is connected to the mobile device (M
S2), the mobile station (MS2) responds (in addition to its control information) that time slot #4 is no longer needed. As a result, the mobile station (MS2) transmits a message indicating that time slot #4 is vacant, arrow B4, to the wireless base station.

As can be seen from FIG. 6A, every third frame time slot #1 is used by the mobile station (MS1), and every third frame time slot #4 is used by the mobile station (MS1).
2) is used. Thus, time slots #1 and #4 of the intermediate frame are vacant. These time slots are accessed by a number of different mobiles. It can also be said that the mobile itself requires more time slots for access, or that subsequent time slots are marked free by the radio base station. . This means that the probability of collision between access messages from the mobile device to the radio base station, ie to the system, is minimized.

The access procedure according to the invention can also be used for half-rate channels as access channels. Figure 6B shows this case, where only one time slot of each frame is used for multi-burst access. In FIG. 6B, the mobile station (MS1) discovers the message in the downlink timeslot of the second frame and a reservation of the mobile station (MS1), arrow A1, is made in this timeslot by the radio base station. The subsequent procedures according to arrows A2 to A6 are the same as those for the mobile station (MS1) in the full rate mode described in FIG. 6A, and the procedures for the mobile station (MS2) and the mobile station (MS3) are also the same. It is.

FIG. 7 is a flowchart illustrating the various steps taken in a mobile device and a radio base station to implement the method according to the invention. Within block 701, one of the plurality of mobiles is in an idle state and transmits data messages over the air on the forward digital control channel DFOCC in time slots each having the format shown in FIG. 4E. Received from the system via the base station. These messages are directed to individual mobiles or to all mobiles that can read this particular DFOCC. Message to all mobile devices,
That is, the broadcast message contains information about the system and information controlling the actions taken by the mobile device during system access.

At block 702, a request for system access is generated within the mobile device. The motive may be in response to a call or a change in system information such as registration control data, or the mobile subscriber desires call access. At block 703, the mobile device reads the reservation field RES1 or RES2 in the burst on the DFOCC from the radio base station and begins access. (Arrow A1 in Figure 6A) Block 7
At step 04, the value of this field is detected and checked in the mobile device to see if it is a value indicating that it is reserved or is vacant by the radio base station. If the values of the reservation fields RES1, RES2 indicate that the time slot is reserved for another mobile, processing is transferred to block 705 within the mobile. On the contrary, reserved fields RES1, (RE
If the value of S2) is that the time slot is not reserved and is "vacant", processing moves to block 706.

At block 705, reserved time slots are discovered by the mobile. The number N that determines the above branching behavior (so as not to enter block 706) is
considered to be the maximum number. If the maximum number N is exceeded (“YES” in block 705), processing is interrupted and block 701
be returned to. On the other hand, if the maximum number N is not exceeded ("NO" in block 705), the process returns to block 703 with a random delay. block 70
At 6, the mobile activates its transmitter and sends the first burst in an access message (arrow A2 in FIG. 6A) to capture the free time slot indicated by the radio base station.

At block 706A, more bursts and reservation fields RE are sent to the radio base station.
The mobile device checks whether S is included in the access message, and processing moves to block 707. Conversely, if this was the last burst in the access message, the transmitted burst is only read by the radio base station, the reservation field (RES) is set to empty, and processing returns to block 701. Meanwhile, the mobile device is waiting for the system to respond.

At block 707, the wireless base station of the system detects the burst transmitted from the mobile (arrow A2 in FIG. 6A).
)I Read. The system validates the data words contained within the burst and detects the contents of the Reservation Reservation Field (RES). If the data word is found to be valid (if the checksum is correct) and if the reserved field indicates that it is reserved, then the system sets the corresponding reserved field RES1, (RES2) on the DFOCC as "reserved". ”.

At block 708, the mobile device registers the reservation fields RES1, RES1, and RES1 set by the system.
2 is received and read (arrow A3). At block 709,
Messages received from wireless base stations are examined. If the mobile detects in block 709 that the reservation fields RES1, RES2 are set to reserved, the mobile can continue accessing and processing returns to block 706 to transmit the next burst. . Conversely, if an empty indication is detected, processing continues at block 710.
will be moved to At block 710, a fault is detected. The number indicating the number of failure occurrences is the maximum number. If the maximum number is exceeded, processing is interrupted and returns to block 701.

Microprocessor controller 130 activated by a signal from control channel message detector 133' to read reservation field RES.
' causes blocks 706B and 707 to be executed at the radio base station. The microprocessor controller 130' then activates the control channel message generator 132' to send control messages to the mobile station (MS1) during the reserved time slot. The microprocessor controller 130' also controls time slot #.
1 is either set as a reserved time slot (block 707) or set as an empty time slot (block 706B).

The other functional blocks in FIG. 7 are executed within the mobile station (MS1) by the microprocessor controller 130 shown in FIG. The microprocessor controller 130 is activated by the control channel message detector 133 to read the control message and reservation fields RES1, RES2 and to activate the control channel message generator 132 to transmit the control message to the radio base station. Ru.

[Brief explanation of the drawing]

FIG. 1 shows a small zone mobile radio system with a small zone, a mobile switching center, a radio base station, and a mobile station.

FIG. 2 is a block diagram of a mobile device utilizing the present invention.

FIG. 3 is a block diagram of a wireless base station utilizing the present invention.

FIG. 4A is a diagram showing a frame structure of a wireless channel utilizing the present invention. B is a diagram showing a time slot format for transmission from a mobile device to a wireless base station or a ground station. C is a time slot for transmission from a mobile device to a radio base station or a ground station, and is a diagram showing a time slot format with a reservation field according to the present invention. D is the time slot for transmission from the wireless base station or ground station to the mobile device.
Diagram showing the format. E is a time slot for transmission from a mobile device to a radio base station or from a ground station to a mobile device, and is a diagram showing two reservation fields according to the present invention.

FIG. 5 is a diagram showing an example of a radio channel frame having six time slots in which a control channel and a traffic channel are mixed.

FIG. 6A shows a multi-burst access method according to the present invention for full rate mode. B. Similar diagram for half-rate mode.

FIG. 7 is a diagram showing a flowchart illustrating an access method according to the present invention.

[Explanation of symbols]

B1-B10 Radio base station C1-C10 Small zone M1-M10 Mobile station MSC Mobile station switching center 101 Speech coder 102 FACCH generator 103 SACCH generator 104 Channel coder 105 Selector 106 2-burst interleaver 107 Modulo 2 addition unit 108 22 burst interleaver 109 sync word/DVCC generator 110 burst generator 111 20 millisecond (ms) frame counter 112 encryption unit 113 key 114 equalizer 115 symbol detector 116 2 burst deinterleaver 117 2
2 burst deinterleaver 118 channels
Decoder 119 Speech decoder 120 FACCG detector 121 SACCH detector 122 RF modulator 123 Power amplifier 124 Transmitter frequency synthesizer 125 Receiver frequency synthesizer 126 Receiver 127 RF demodulator 128 IF demodulator 129 Signal level meter 130 Microprocessor controller 131
Keyboard display 132 Control channel message generator 133
Control channel message detector 134 Time switch 101' Speech coder/data 102' F
ACCH generator 103' SACCH generator 104' Channel coder 105' Selector 106' 2-burst interleaver 107'
Modulo 2 adder 108' 22 burst interleaver 109'
Synchronization word/DVCC generator 110' Burst generator 111' 20 millisecond (ms) frame counter 112' Encryption unit 113' Key 114' Equalizer 115' Symbol detector 116' Two-burst deinterleaver 117'
22 burst deinterleaver 118' channel decoder 119' speech decoder/data 120'
FACCH detector 121' SACCH detector 122' RF modulator 123' Power amplifier 124' Transmitter frequency synthesizer 125'
Receiver frequency synthesizer 126' Receiver 127' RF demodulator 128' IF demodulator 129' Signal level meter 130' Microprocessor controller 132
'Control channel message generator 133' Control channel message detector 1 Channel handler 1 2 Channel handler 2 3 Channel handler 3

Claims (10)

[Claims] 1. From one of a number of mobile stations (MS1) communicating with a mobile radio ground station, accessing the mobile radio ground station system in a time slot of a TDMA frame and transmitting an access message on a digital control channel. A method for accessing a radio base station in a system by a mobile station (MS1) in order for the mobile station (MS1) to complete an access message in a reserved time slot on said digital control channel. , frames (
F4, F7, F10) has a predetermined position (#1),
A reservation field (
A method characterized in that a mobile station (MS1) continues to access a radio base station (BS) in the system by transmitting a radio base station (BS) to the radio base station. Claim 2: The total number of time slots in a frame (
1 to 6) less than one frame (F1, F2
,...), when the radio base station sends a control data message to different mobile stations (MS1, MS2,...) in the system, The mobile station (MS1) listens to the control data message, and the specific time slot (#1) in the frame (F4) used to transmit the control data message from the radio base station to the mobile station Method according to claim 1, characterized in that the control data message is to be transmitted to the radio base station together with the information that it is reserved for the next control data message sent from the radio base station to the radio base station. 3. When the mobile station (MS1) that was trying to access the radio base station succeeds in the access, a certain time slot (1, F4: time slot #1 of frame F4) is used by the mobile station (MS1). and the radio base station sends the control message to the mobile station (MS1), and after this mobile station (MS1) receives this control message, the reserved time slot (1, F7) Claim 2, wherein the control message from the mobile device is sent to a wireless base station (BS).
The method described in. 4. The mobile station for which the time slot was reserved is sending the last data control message occupying the time slot (#1), and at the same time the mobile station for which the time slot (#1) was reserved is , wireless base station (BS
4. Method according to claim 2, characterized in that sending a message that it can be made available at ). 5. The data control message (D) sent from the radio base station (BS) via a digital control channel (CC) is vacant when it is used as a control channel rather than a traffic channel. , a certain time slot (#1 or #4)
The method according to claim 1, characterized in that it occupies reserved fields (RES1, RES2) in . 6. The reserved fields (RES1, RE
S2) is composed of two field parts (RES1, RES2) in a time slot used as a digital control channel (CC), and these two field parts are used as a low-speed control channel in a traffic channel (TC). 6. The method according to claim 5, characterized in that it corresponds to (SACCH) and Digital Verification Color Code (DVCC). 7. The mobile device (MS1, MS2, . . .
) to the radio base station (BS) via a digital control channel (CC).
) is characterized in that it occupies a reserved field (RES) in the traffic channel (TC) corresponding to the fields occupied by the slow control channel (SACCH) and the digital matching color code (DVCC),
The method according to claim 1. [Claim 8] A certain frame (F4) reserved for a specific mobile station (MS1) in a radio base station (BS).
A specific time slot (#1) of the first reserved frame (F4) is followed by a predetermined frame interval (F5-F6), and then the time slot (#1) of the frame (F7) is Claim 1 characterized in that the same time slot (#1) is reserved, thereby leaving a number of frames with free time slots for access from another mobile station (MS2, MS3). The method described in. 9. When the system is operating in full rate mode, two different time slots (#1, #4) of each frame (F1, F2, . . . 5. A method according to claims 1 to 4, characterized in that the method is accessed and reserved by: ). 10. When the system is operating in half-rate mode, only one time slot (#1) of each frame (F1, F2,...) is processed by only one mobile station (MS1). 5. A method according to claims 1 to 4, characterized in that the access is accessed and reserved.