KR920003829B1 - Initialization of communication channel between a subscriber station and base station in a subscriber communication system - Google Patents

Abstract

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Description

Communication channel initialization characteristic device between subscriber station and base station

1 is a suitable embodiment of the subscriber communication system of the present invention.

2A and 2B illustrate processing routines for establishing communication between a base station and subscriber stations in a network such as the base station.

3 shows a processing routine for refining the timing of subscriber station signaling to the base station.

4 is a diagram showing a processing routine for transmitting DC signal information through an assigned voice data communication channel.

* Explanation of symbols for main parts of the drawings

13: exchange 14: remote connection processing unit

18: master clock 19: multiplexer unit

20: channel module 23: channel control unit

24: voice codec unit 26: Lee Sun-sik track appearance

28: T1 trunk 41: subscriber station

100: pressurizer control operation 104: base station

106: change demodulator 112: baseband processor

115: handset 116: data processor

BBP: Base Band Processor

CCT: Channel Control Task

CCU: Channel Control Unit

CRC: Cyclic Redundancy Check

EEPROM: Electrically Erasable Programmable Read Only Memory (PROM)

FT: Fractional Timing

MUX: Multiplexer Unit

NID: Network Identification Number

PCM: Pulse Code Modulation

RCC: Radio Control Channel

RELP: Residual-Excited Linear Prediction

RF: Radio Frequency

RPU: Remote-Connection Processing Unit

RUW: Refinement Unique Word

SCT: Subscriber Control Task

SID: Subscriber Indentification Number

SSB: Switch-hook State Buffer

TDM: Time Division Multiplexed

UW: Unique World

VCU: Voice Coder Unit

The present invention relates to subscriber communication devices and, in particular, directly relates to communication channel initialization between a subscriber station and a base station in such a subscriber communication device.

US Pat. No. 4,675,863, entitled "Subscriber RF Telephone Device for Simultaneously Providing Multiple Voice and / or Data Signals on a Single or Multiple RF Channel," published June 23, 1987 It is explained.

The present invention provides a subscriber communication system in which a base station network is included with a plurality of subscriber stations, and control information is communicated between the base station and the subscriber station by a base station at a frequency selected from a plurality of predetermined frequencies. The base station sends a control message via the RCC. The control message contains the network number unique to the base station. Each subscriber station processes the network number in the control message received through the RCC, allowing the subscriber station to process the control message depending on whether the subscriber station is in the same network as the base station.

Each subscriber station is also operable in one search mode, and in such a search mode it searches by successively sending an RCC acquisition message at each predetermined frequency, where each acquisition message contains a unique identification number unique to the subscriber station. The base station processes the subscriber identification number within an acquisition message received through the RCC to determine if the subscriber station is in the same network as the base station, and this processing of the subscriber identification number is performed by the subscriber station in the same network as the base station. Send a receipt notification to the subscriber station from which the RCC was obtained by the subscriber station when indicating that it is present.

The present invention also provides a subscriber communication device in which communication timing transmitted by the subscriber station over a predetermined communication channel between the base station and the subscriber station is refined according to the initial setting of the communication channel.

The base station includes a master clock for providing timing signals of the communication device. The subscriber station includes an internal timing generator, which generates a subscriber station timing signal for timing signals transmitted from the subscriber station through a communication channel established from the subscriber station to the base station, and sets the timing of the internal timing signal. Provide a refinement signal to indicate. According to the initial setting of the communication channel between the base station and the subscriber station, the subscriber station transmits a refinement signal from the subscriber station to the base station through the designated communication channel, and the base station is provided between the timing of the communication device timing signal and the timing of the refinement signal. Process refinement signals received from subscriber stations with respect to communication device timing signals to determine offset magnitudes. The base station delivers the determined offset size to the subscriber station, and the subscriber station processes the offset size delivered from the base station to adjust the subscriber station timing signal to reduce the offset.

The present invention further provides a subscriber communication device, wherein both DC signal information and voice data signal have a line appearance connecting a base station to a central office and a line interface connecting a subscriber station to a subscriber terminal. It is communicated through one assigned channel. The communication device processes the DC signal information for the communication through the assigned channel between the line appearance and the line connection by detecting the DC signal information through the line appearance and / or the line connection, and communicates through the assigned channel instead of the voice data signal. The condition of the detected DC signal information is determined.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, one suitable embodiment of the subscriber communication device of the present invention includes a base station 104 and a plurality of subscriber stations 41. This embodiment is useful with one base station described in the US patent application filed on the same day under the name "wireless digital telephone apparatus", and the same reference number is used in both applications to designate common parts.

The base station 104 includes an exchange 13, a remote connection processing unit (RPU) 14, a master clock 18, a multiplexer unit (MUX) 19 and a channel module 20. The exchanger 13 is connected to the central office by a plurality of two-line track emergences 26. The exchange 13 is connected to the channel module by the T1 trunk 28 and the MUX 19. The MUX 19 multiplexes different communication channels in different timeslots via the T1 trunk 28. The channel module 20 includes a channel control unit (CCU) 23, a voice codec unit (VCU) 24, and a modulator 106. The CCU 23 places the communication channel in different radio frequency (RF) channels. The VCU 24 determines the conditions of the voice communication signal carried over the communication channel. Modulator demodulator 106 enables the transmission and reception of voice and data communication signals over an assigned RF channel. The CCU 23 transfers a communication signal between the allocated RF communication channel and the allocated communication channel in one assigned timeslot in the T1 trunk 28. The RPU 14 monitors the state of the timeslot and the state of the RF channel in the T1 trunk, and assigns the communication channel to the scheduled timeslot and the scheduled RF channel according to the scheduled assignment routing. The CCU 23 exchanges control messages with the subscriber station 41 via a radio control channel (RCC) in a predetermined time slot of a predetermined RF channel.

Each subscriber station 41 includes a modulator 107, a baseband processor 112 and an internal timing generator 113. The baseband processor 112 is connected to one subscriber station such as a telephone and / or data processor 116 by a two-wire connection line 27. The baseband processor 112 includes two program embedded modules, a subscriber control operation (SCT) module 100 and a channel control operation (CCT) module 105. The CCT 105 is responsible for word synchronization and framing, collision detection and resolution, and error detection. The CCU 23 and the mode CCT 105 listening in the RCC must thoroughly check for valid RCC messages in all RCC slots. The CCT 105 does this by closely examining the existence of a UW in a window ± 4 symbol around the nominal unique word (UW) position based on the master system timing. The CCU 23 listening at the RCC closely examines a unique word within a window ± 3 symbol around the nominal UW position. The search algorithm moves the data until it finds a UW pattern or until all possibilities are exhausted. Once a pattern is found, the RCC message is considered valid only when the RCC checksum is correct.

SCT 100 implements the RCC frequency investigation algorithm. The purpose of the RCC investigation is to allow subscriber station 41 to discover the base station 104 of the same network as subscriber station 41 as soon as possible, and to allow subscriber station 41 to attempt to communicate with a known inappropriate network. Each base station 104 has a unique network identification number (NID). Each subscriber station 41 has a unique 24-bit unique subscriber identification number (SID). The SID is stored in one EEPROM in subscriber station 41. All SIDs in one particular network are stored in a network database at base station 104.

RCC surveys can be active or passive. Active RCC lookup is performed only when call orientation is pending. The subscriber station 41 is accepted into a network and determines the network identification number only through an active investigation. When the call orientation is not pending, the unit performs a manual investigation using a known home network identification number (home NID). By reacquiring the correct RCC channel.

If all possible RCC frequencies have been successfully attempted in either irradiation mode, the SCT 100 attempts a hard reset. This may potentially erase system failures that prevent the subscriber station 41 from obtaining synchronization. This hard reset retrains the demodulator. Modulator demodulator training applies the demodulator filter to the current environmental conditions. If the handset is off-hook when all frequency attempts have failed, the SCT 100 outputs the busy RCC to the phone handset 115 as soon as possible.

Each time the SCT 100 forms a reset it reads the SID and NID from the EEPROM. If no NID is present in the EEPROM, it is set to zero by default. When the SCT 100 obtains synchronization on the RCC frequency in one manual survey, the SCT compares the received NID with the initially stored NID and rejects all RCC frequencies with non-matching NIDs.

Active RCC frequency lookup starts only when call orientation is outstanding. At the end of such a call orientation unresolved state, the user hangs up the handset or the unit enters a failed state.

Active investigation then becomes a passive investigation. If the SCT 100 attempts all RCC frequencies but fails, the SCT 100 transitions to one failure state and sends a re-command tone to the handset 115. This clears the call orientation outstanding state and forces the probe mode to transition from active to passive. The SCT 100 determines to join the network, and the investigation ends.

The SCT 100 determines the subscriber station network subscriber NID through a normal call setup procedure. The SCT 100 performs a frequency survey, and when the SCT 100 obtains synchronization for one RCC frequency, the SCT sends a CALL REQUEST RCC message. If the base station 104 recognizes the SID, it either responds with a call connection message if it wants to end the call or with a CLEAR INDICATION message with a clear code if it is too busy to end the call. In either case, the investigation ends and memory retention is stored in the EEPROM by the subscriber station 41 during the NID power interruption in the data field of the RCC message.

If the base station 104 does not recognize the SID, it sends an erase indication message to the subscriber station 41 with an unknown subscriber erase code. Next, the SCT 100 generates the next frequency, and causes the RCC to be examined at the next frequency generated. Without confirmation from the base station, the SCT 100 generates the next frequency for investigation, and a new frequency may be requested by the CCT 105 due to loss of synchronization.

After finding the correct network, whenever the SCT 100 loses RCC synchronization, it performs a manual investigation and transitions from the voice channel to the RCC. If the network number is not verified, a manual investigation is performed, but the call orientation pending state is cleared. If the subscriber station 41 detects an off hook (service request), it starts an active investigation. The next event causes the SCT 100 to generate the next RCC frequency in the manual search mode. (a) New frequency request from CCT 105 due to AM hole detection failure or loss of RCC synchronization; (b) return from the voice channel to the control channel; Or (c) RCC synchronization achieved in the wrong network.

To increase the speed of the manual survey, the SCT 100 stores up to six frequencies that match the home base station 104. When active or passive investigation is required, the frequency generating algorithm alternates between the stored table of RCC frequencies and the frequencies from the incremental frequency counter. This gives priority to the most likely frequencies and accelerates the acquisition of the base station after a brief violation.

Each time the SCT 100 obtains synchronization in the RCC, it checks for a match between the stored NID and the received NID. If no match is found, the SCT 100 has acquired a synchronization in the wrong network, and the SCT 100 attempts to generate a new frequency and obtain a synchronization at that frequency. If the NID matches, the SCT 100 finds the correct network and the investigation ends.

The general routine performed in the active survey mode is summarized in relation to FIG. The SCT 100 at the subscriber station 41 performs the routine 120, where a learned message containing the SID of the subscriber station 41 is being used by the assigned network base station 104 of the subscriber station. It is delivered continuously at each frequency. The RPU 14 at the base station 104 performs a routine 21 to determine if the SID contained in the acquisition message received at the given RCC frequency matches the SID in the list of SIDs stored at the base station. If the SID in the learned message delivered by the subscriber station matches one of the SIDs stored in the base station 104, the base station 104 sends a routine 122 for sending an acknowledgment message to the subscriber station over the determined RCC frequency. To perform. The confirmation message contains the NID of the base station. The subscriber station 41 responds to the confirmation message by performing a routine 124 to store the NID in the subscriber station memory.

If the SID in the acquisition message delivered by the subscriber station does not match any of the SIDs stored in the base station 104, it sends a negative acknowledgment message to the subscriber station over the specified RCC frequency. Upon receipt of the negative process message, subscriber station 104 performs routine 125 to change the fixed RCC frequency, and repeats routine 120 to deliver the learned message to the fixed changed RCC frequency.

A general routine performed in the manual search mode is summarized in relation to FIG. 2B. The subscriber station 41 performs a routine 127 for continuously receiving control messages transmitted on each of the RCC frequencies used in the network to which the subscriber station has been assigned. At the given RCC frequency, base station 104 performs routine 128 to transmit a control message including the NID. For a control message received at a given RCC frequency, subscriber station 41 performs a routine 129 to determine whether the NID in the received control message matches the NID stored in the subscriber station. If the NID matches, the subscriber station 41 performs a routine 130 that allows the subscriber station 41 to process control messages from the base station 104. If the NID does not match, the subscriber station 41 performs a routine 131 to change the fixed RCC frequency (receives control messages), and the routine 129 comparing the NID is repeated.

Timing refinement is performed at the beginning of every voice connection made over the assigned communication channel. The intention is to tune the transmit station timing of the subscriber station so that it is within ± 3% of the master symbol clock of the base station.

In order to achieve ±% tolerance, the type offset magnitude "Δt" of the fragment is collected in multiple frames at the subscriber station. Each transmission burst from the base station provides another data point in the fragment's time offset-size sample list. Periodically, the sample means, " means [Delta] t, ”are calculated to produce an estimate of the actual fragment time offset. This assessment is used to adjust the timing generator inside the subscriber station and to get closer to the desired size. This process continues until the base station detects that the subscriber station timing is within ± 3% of the current symbol timing magnitude.

The base station CCU 23 automatically enters the refining operation when it is assigned a Venus channel. The CCU 23 instructs the demodulator 106 to start the subdivision and continue to transmit subdivision bursts. Each burst contains timing information of power, symbol timing and fragments for the subscriber station.

The base station CCU 23 successfully receives the subscriber subdivision burst if the subdivision unique word (RUW) is found, and the CRC is verified to be correct. If at any time the base station CCT 23 does not succeed in receiving the subscriber burst, the next base station transmission burst contains null for symbol timing. Also, if the base station determines that the link quality of the subscriber burst has fallen below its intended level, the base station notifies the subscriber station of this with a command byte by setting the "ignore FT" bit.

The subscriber station discards the fragment time information contained in the next burst.

The subdivision operation is completed successfully when the base station reads three consecutive fragment time values within ± 3% of the master timing signal from the master clock 18. Successful segmentation is signaled to the subscriber station via the command byte by setting the "StopRef" bit. The subscriber station affirms such termination by clearing the bit in the next reverse channel burst. The subscriber station then enters voice operation. As soon as this positive confirmation is detected, the base station enters voice operation.

If the ± 3% target has not been reached, the subdivision is indicated by the base station after 67 frames (3.0 seconds). This signals the subscriber station via the command byte by setting the "AbortRef" bit. The abandoned subdivision operation is affirmed by the subscriber station in the same manner as the stop subdivision operation. The subscriber station then destroys the voice channel, and as soon as the base station detects an acknowledgment, the base station destroys the voice channel.

If the base station fails to receive the subscriber station's acknowledgment after the first transmission (ie, no RUW is found and the CRC is not good), it transmits the incoming order second. If the base station fails to receive the acknowledgment of the subscriber station even after the second transmission, it automatically enters voice operation when sending the "StopFef" bit or destroys the voice channel when sending the "AbortRef" bit.

Subscriber CCT 105 enters the segmentation task upon receipt of the voice channel assignment. As soon as the base station subdivision burst is received, the subscriber station shall use the contents of the "Pwr" bytes to calibrate the transmit power and the fragment timing bytes to use the symbol timing to correct the symbol timing.

The fragment timing offset magnitude Δt received from the base station is stored as they arrive. Once five valid sizes are collected, the subscriber calculates a sample variance to determine their spreads. If this sample variance is too large, a sample of stock prices will be collected. Once the sample variance is small enough or the effective sample coefficient reaches 16, the sample mean (mean Δt) is calculated and used to adjust the timing signal of the fragments sent to the base station. Following this adjustment, the buffering operation is repeated once again.

If the RUW is found and the CRC proves to be fast, the subscriber station CCT 105 successfully receives the base station subdivision burst. The subscriber station ignores base station bursts that were not successfully received. The subscriber station also ignores the timing size of the fragments when commanded to do so by the base station. There is only one case where the subscriber station ignores the power magnitude in the burst. This is the magnitude of power within the first successfully received burst (i.e., such power regulation produces a "spike" effect on the next reverse channel burst).

The subdivision operation is successfully terminated under command from the base station. Voice operation begins immediately after the subscriber station acknowledges the incoming station's incoming order.

The subdivision operation is stopped after 67 frames (3 seconds) under command from the base station. At this time, the voice channel is immediately destroyed after acknowledging the command from the base station. The subscriber station stops subdivision after receiving 77 frames of poor subdivision (3.5 seconds). This timing skew allows the user to receive an "AbortRef" command before terminating and destroying the subscriber station voice channel.

The sampling variance must fall below one threshold before adjusting the timing of the fragments at the subscriber station 41. Determination of such limit values is somewhat arbitrary, but provides adequate limit sizes from the following analysis.

In the probability process, 75% of all samples are within 2 standard deviations from the mean, so if the calculated double standard deviation is found within the interval (-5%, + 5%), 75% of the samples are 5 It is known to be within%, which gives a great deal of confidence that the surface mean is accurate and can be used for feedback control.

Since the control step size is T / 200 and T is the symbol time, the interval [-5%, + 5%] corresponds to [-10, +10] in the intermediate step. Therefore, the deviation should be within the interval [-5, +5] or the sample variance should be less than 25. Since sample variance is easier to calculate than the standard deviation, sample variance is used in practice. The formula is:

(Δt₁-평균Δt)²}/(n-1)…………………………방정식 1V ₂ = {

(Δt ₁ -average Δt) ² } / (n−1)... … … … … … … … … … Equation 1

"V" is the sample variance, "Δt ₁ " is the i-th calculated fragment time offset size sample, "n" is the sample size, and "average Δt" is the mean Δt calculated for the n sample.

The approach to subdivision operation described herein permits acceleration of operation under good conditions and provides difficult operation under conditions. If the short time evaluation is good, the subdivision will end within 4 frames (180ms). In a less ideal situation, all 16 frames on average need to be calculated, which takes about 19 frames (855 ms). In the worst case, the algorithm can be driven to an acceptable upper limit of 67 frames (3 seconds), but it is not shown that speech operation will be possible even in such extreme situations (it is subdivided when the maximum coefficient is reached). This is the reason for the abandonment) The general routine performed by the base station 104 and the subscriber station 41 to achieve the timing subdivision operation is summarized in relation to FIG. The subscriber station 41 performs a routine 134 to transmit a continuous frame of subdivision signal bursts timed by the internal timing generator 113.

The base station RPU 14 processes each received subdivision burst in relation to the system timing signal from the master clock 18 to determine an offset magnitude Δt for each burst between the timing of the system timing signal and the subdivision signal timing. The routine 135 is performed.

The base station CCU 23 performs a routine 136 to determine whether the predetermined number "n" of the continuously determined offset size Δt is less than or equal to the predetermined size "U". When the base station CCU 23 determines whether the predetermined number "n" of the successive determined offset magnitude Δt is less than or equal to the predetermined size "U", the base station transmits a stop subdivision signal to the subscriber station 41. ). The BBP 112 at the subscriber station performs a routine 138 which terminates the transmission of the subdivisional operation signal returning a positive signal to the base station, and responds to the stop subdivisional operation signal by performing the next routine 138a. The BBP 112 then performs a routine 139 to enable normal communication over the established communication channel with the ground station 104.

The base station CCU 23 responds to the acknowledgment signal by performing a routine 138b in the routine 138 that enables normal communication over the established communication channel with the subscriber station 41.

The base station CCU 23 performs the duration " D " timing routine 141 of the routine 136, where it is determined whether all " n " of the continuous offset size Δt is less than the predetermined size " U ". If such a determination was made within the predetermined duration " S " (i.e., D > S), then the base station CCU 23 performs a routine 142 that sends a disclaimer signal to the subscriber station 41. The BBP 112 at the subscriber station 41 performs a routine 143 which sends a positive signal back to the base station and a routine 144 which destroys the established communication channel at the base station to the abandoned signal. Answer. The base station CCU 23 responds to the positive signal from the subscriber station 41 by performing a routine 145 to destroy the communication channel established at the base station.

The predetermined number "n" of the successively determined offset size Δt is predetermined by the routine 141 for timing the duration D of the routine 136 for determining whether the predetermined number "n" is less than or equal to the predetermined size "U" (i.e., D < S). The base station CCU 23 is scheduled to the subscriber station 41 before the end of the duration S and before determining whether the predetermined number “n” of the continuously determined offset size Δt is less than or equal to the predetermined size “U”. One routine 147 to send the offset size Δt is performed.

The BBP 112 at the subscriber station 41 performs a routine 148 to calculate the average offset size (average Δt) from the last “m” offset size Δt received from the base station (as described above). Similarly, unless otherwise validated by achieving "ignore ET", BBP 112 may also calculate the average offset size (average) for which the predetermined number "P" of the received validation offset size Δt is calculated according to routine 148. The routine 149 is performed as long as it determines whether it is within the predetermined tolerance "R" of Δt).

If BBP 112 determines that the predetermined number " p " of the verification offset size Δt received according to routine 149 is within the predetermined tolerance R of the average offset size (average Δt), then BBP 112 calculates the calculated value. A routine 150 is performed to adjust the timing of the internal timing generator by the average offset size (average Δt).

If BBP 112 determines that the predetermined number "p" of the verification offset size Δt received according to routine 149 is not within the predetermined tolerance of the average offset size (average Δt), then BBP 112 determines A routine 151 is counted that counts the number of negative decisions, and when the predetermined coefficient " Q " corresponding to one predetermined duration is reached, the BBP 112 calculates the internal timing generator by the average offset size (average? T) calculated. Perform the routine 150 to adjust the timing of.

In the subscriber communication system, the two-wire line connection 271 at the subscriber station 41 moves DC signal information between the two-wire line appearances 26 at the central office 25. Information transmitted from subscriber station 41 to base station 104 in the " reverse channel " direction includes a change in supervised state, dial pulse digits, and a switch hook flash. Front channel DC signals include features such as synchronous rings, distinctive rings, and coin box operation.

It is desirable to provide as much simplicity as possible within the limits of the system's TDM characteristics. Signal signal names are refined by quantifying the following performance attributes. In order to optimize the signal path dependence, signal delay and signal resolution, these parameters, the system uses one waveform code to digitally convey DC signal information from the line connection 27 of the subscriber station to the line appearance 26 of the central office. Use technique.

The change in switch hook state is monitored by the baseband processor 112 in the subscriber station 41. Timer interference in the EM band processor occurs every 1.5ms with switch-hook. Or 30 samples per TDM frame. Each sample is stored as a single bit (on hook or off hook) in the switch-hook state buffer (SSB) 114. SSB 114 includes 60 sample bits, but typically only 45 of these bit positions are actively used. The remaining bits are taken into account in the elastic buffer overflow capability. The nominal 45 bits provide 67.5 ms of switch hook state information. The SCT 100 uses the SSB to determine changes in supervisory status such as service requests, responses, and blocking. The SSB is also monitored for DC signal events while the call is active.

DC signal events can only occur during active voice operation. SSB 114 is checked for events once every TDM frame (every 45ms). An event is detected by using a cluster count. Starting at 16 bits, the SSB 114 performs up to the 45th bit, and the number of steps is incremented every on-hook bit and decremented for every off-hook bit. If the coefficient reaches the limit specified by the terminal stage number T _CC , a DC signal event is declared. The step number is not allowed to be negative or not exceed T _CC . The stage count also continues across the frame boundary and the stream of hook switch samples appears to be continuum.

Aggregate technology has the effect of detecting on-hook clusters (clusters) in SSB 114 even when there is a sudden failure. The hit is rejected based on the selection of T _CC .

Once a DC signal event is detected, the subsequent transmission burst is used as one control burst. Voice information in the burst is replaced by DC signal information using the current voice modulation level. The oldest 30 bits of SSB data, representing a 45ms switch-hook state, are encrypted in bursts.

If a continuous DC signal event is detected at SSB 114, control bursts continue to be sent in consecutive frames.

In some cases an additional control burst is required following a series of one or more control bursts, even if no signal event is declared in that frame. The only condition in which additional control bursts are required occurs when leaving the base station 104 in an on-hook state, ending with the preceding control bus one on-hook bit. If additional control burst is required, the baseband processor 112 at base station 104 should ensure that the last switch hook state is set off-hook so that the VCU 24 returns to the off-hook state.

The first six words of each control block contribute to an arbitrary flag pattern. The flag pattern at this time allows the control block to be detected during normal voice operation.

Fourteen words of DC signal data follow this flag pattern. The words are composed of seven sets, each set containing two words of information. The least significant bit of each word contains no information and is arbitrarily set to zero. These bits, however, can and should be used for error detection. The remaining 15 bits of each word in the set collectively contain 30 bits of switch-hook status information. This information is stored chronologically from the first word to the second word in the set and from the most significant data bit to the least significant data in the word. Each set is exclusive ORed with a unique bit pattern to avoid misdetermination because it is repeated except for incorrect patterns.

The receiving VCU 24 at the base station 104 determines the presence of a control block opposite to the voice block by a simple majority vote decision on the flag pattern word at the block head. If the majority voting limit is exceeded, the block is declared to be a control block. If RELP analysis continues during the control block processing, normal RELP data is replaced with RELP silence.

Once a control block is detected, the DC signal state information that the block contains is decoded using a simple majority vote decision. Exclusive-OR conversions should be removed before most vote operations. If the block is removed, no change in switch-hook state occurs.

Once the 30-bit contents of SSB 114 are decoded by VCU 24, it is translated into T1 A / B signal bits. In the case of a two-wire switch-hook state, the 30SSB bits exactly match the required 30 bits of the A-bit signal data.

The T1 A-bit is placed in a first-in, first-out queue for transmission to the base station 104 via the PCM highway. The corresponding MUS 19 provides the VCU 24 processor with an interference just prior to the A-bit T1 signal frame to allow the processor to scan the appropriate signal bits of the correct PCM byte.

The oldest state is infinitely repeated when no control block arrives to refill the A-bit queue. In the case of DC signaling, the SCT 100 ensures that the last state in the SSB 114 is off-hook.

Following one call setup, the CCU 23 at the base station 104 initializes the VCU 24 to the off-hook state. The CCU 23 turns off the VCU 24 immediately before the subdivision operation is finished. In the case of call termination, CCU 23 off-hooks VCU 24 after a response is detected. Control bursts are not used for these supervisory state transitions.

Once response operation is established, control bursts are used to transmit DC signal events to base station 104. If a block is detected at the subscriber station 41, the base station VCU 24 signal state remains on-hook and the call is cleared via the RCC clear request burst.

By properly selecting the DC signal parameters it is possible to adjust the performance of the system. To help detect and correct errors, flag patterns and SSB majority votes are selected in 8-bit segments (aligned in one direction with byte boundaries). Most votes on the flag pattern are taken for 12 bytes before. For SSB 114, there are four independent majority votes, including one for each byte. If any one of the majority votes fails, the entire majority vote is considered failed. The selected parameter size is as follows.

Single cluster factor… … … … … … … … … … … … … … -15

Flag pattern majority vote… … … … … … 6 out of 12 (bytes)

SSB majority vote… … … … … … … … … … 4 out of 7 (bytes)

The selection of the terminal cluster coefficients represents the average between hit rejection and faithful reproduction of the DC signal pulses. The minimum effective on-hook pulse duration is 29 ms on-hook generated by 20 pulses per second operating with 58% brake.

When the terminal cluster clunt is 15, a hit of 22.5 ± 1.5 ms or less is rejected. This rejection limit is well below the required 29ms equivalent to a 18.5 sample multiple.

This limit implies that a control block is sent if at least 50% of the TDM frames are occupied by a handcell that is on-hook. The 45 SSB bits contain 67.5ms of signal state information and provide 22.5ms of foresight data to allow the buffer to make "go / no / go" decisions. Without foresight data, it is not always possible to send a preceding switch-hook-transition bit in time.

Flag pattern limits are most important to avoid false control block detection and lost control blocks. Although undesirable, false control block detection during voice operation is not critical to the system. Error detection only generates some remote hit possibilities with a 45ms silence and a central office preference. The loss of the control block can be much less acceptable, even more so in the case of control bursts because it impedes the subscriber's ability to perform signaling. With this in mind, the flag pattern limit is set to 6 (fixed position) 8 bits (byte boundaries) of 12 possible. The likelihood of such occurrences in random noise (RELP data appear like white noise) is ^2-6 × 8 × (two of 12 choices) or 3.2 × 10 ⁻¹² . With a block transfer period of 22.5ms, this match has a rate that is expected to occur once for 200 consecutive voice interactions. This analysis of control block loss is more difficult than when it is particularly expected that errors will occur in bursts, but such detection techniques provide good practice.

The SSB majority vote threshold allows error correction in the signal data. Because the DC signal bits are stored in the set, the corresponding SSB words are separated by many bit positions. This natural interleaving ensures that one burst error wipes out three full sets and does not pollute the majority of votes yet.

Voice channels that allow for acceptable voice quality will also use this technique to provide very reliable DC signals. In our system, this signal resolution is 1.5ms. The signal delay through this system is approximately 80ms. This delay consists of a 67.5ms SSB window, 6ms transmission time and base station processing time. These schemes make the system DC signal simplicity comparable to existing digital loop carrier systems.

In a similar manner, DC signal information may be transferred from the line appearance 26 at the base station 104 to the line interference 27 at the subscriber station 41.

A general routine performed by base station 104 and subscriber station 41 to detect and transmit DC signal information over a communication channel assigned to a voice channel is summarized with reference to FIG. The generating station 155 referred to in FIG. 4 is either the base station 104 or the subscriber station 41 depending on the origin of the DC signal information, and the receiving station 156 is the other of those two stations.

The generating station 155 performs one routine 158 to monitor the signal at the line appearance / connection, and performs one routine 159 to buffer the monitored signal according to the routine 158, and the routine 159 The routine 160 detects the DC signal information from the buffered signal according to the present invention, and adds the detected DC signal information to the DC signal data to form a control block having a flag pattern to replace the voice data signal. A routine 161 for determining a condition of the detected DC signal information for communication through the allocated channel, and transmitting a control block as a control signal burst to the assigned communication channel in place of the voice information. Do this.

Receiving station 156 performs a routine 166 to determine the presence of a control block in one signal burst received over the assigned communication channel by recognizing the flag pattern in the signal burst. The receiving station 156 then performs a routine 167 to reformat the DC signal information in the control block into a standard DC signal format for transmission to the line appearance / connection.

Finally, the receiving station 156 performs a routine 168 for transmitting the reformatted DC signal information to the line appearance / connection at the receiving station 156.

Claims (17)

A plurality of base stations are included in each of the separated networks, and the base stations in each network are selectively communicated with a plurality of subscriber stations, and through one radio control channel (RCC) at one frequency selected by the base station from a plurality of predetermined frequencies. Means for transmitting control information to the subscriber station, each base station comprising means for sending a control message via the RCC to a subscriber station in the network and for transmitting a unique network number to such base station; Each subscriber station in the system comprises means for receiving a network number from which base station in the system via a respective RCC, allowing the subscriber station to determine if it is in the same network as the particular base station with the particular network number. Subscriber communication system. 2. The apparatus of claim 1, wherein each subscriber station comprises means for examining the RCC frequency by continuously transmitting an RCC acquisition message at each of the predetermined frequencies, each acquisition message comprising a unique identification number unique to the subscriber station, and Means for the base station to process the subscriber identification number in the aforementioned acquisition message received through the RCC to determine whether it is in the same network as the base station, and the aforementioned processing of the subscriber identification number is such that the subscriber station is in the same network as the base station. And means for transmitting an acknowledgment signal to the subscriber station obtained by the subscriber station when indicative of being within. Each base station includes a plurality of base stations, each base station in each network being selectively communicated with a plurality of subscriber stations, through one radio control channel (RCC) from a plurality of predetermined frequencies to one frequency selected by the base station. Means for transmitting control information to the subscriber station, each base station including a master clock for providing system timing signals, and each subscriber station transmitting from each subscriber station to one base station over a predetermined communication channel An internal timing generator for generating one subscriber station timing signal for the timing of the received signal, and means for providing a subdivision signal timingd by the subscriber station timing signal, for each communication channel initialization from the subscriber station to the base station. Available means Means for processing, by the base station, each sub-station signal received from the subscriber station in relation to the system timing signal to determine any off-cell size between the timing of the system timing signal and the sub-operation signal timing. Means further comprising means for sending the determined off-cell size, and coupled to an internal timing generator for processing the off-cell size transmitted from the base station such that the subscriber station adjusts the subscriber station timing signal to reduce the aforementioned off-cell. Subscriber communication system characterized in that it further comprises. 4. The subscriber station processing unit of claim 3, wherein the subscriber station subdivision signal transmitting means transmits a continuous frame of subdivision signal bursts, the base station processing means determines one off-cell size for each received subdivision signal burst, and the subscriber station processing means And a subscriber communication system for processing the predetermined number of consecutively received off-cell sizes to adjust the timing of the subscriber station timing signal. 5. The subscriber communication system according to claim 4, wherein each base station includes means for terminating the communication of the above-mentioned predetermined off-cell size when the base station determines a successively determined off-cell size of the predetermined number. 6. The base station communication means according to claim 5, wherein the base station communication means delivers a stop subdivision actuation signal to the subscriber station when the predetermined number of consecutively determined off-cell sizes is less than the predetermined size, and the subscriber station subdivision actuation signaling means transmits the subdivision actuation signal. And responding to the reception of the stop fine operation signal by stopping the operation. 7. The subscriber communication system according to claim 6, wherein the subscriber station responds to the reception of the stop subdivision signal by enabling normal communication through the communication channel defined at the subscriber station. 5. A subscriber communication system according to claim 4, comprising means for destroying a given communication channel when said determined off-cell size remains above a predetermined size for a predetermined duration. 10. The subscriber station of claim 8, wherein the base station communication means sends an abandon signal to the subscriber station when the determined off-cell size remains above a predetermined size for a predetermined duration, and sends a positive signal to the base station. And the subscriber station responds to the receipt of the abandon signal by destroying the established communication channel in the base station, and the base station responds to the receipt of the positive signal by destroying the established communication channel in the base station. 5. The method of claim 4, wherein the subscriber station processing means calculates an average off-cell size from a predetermined number of processed off-cell sizes, and wherein the predetermined number of processed off-cell sizes is within a predetermined tolerance of the calculated average off-cell size. And a calculated average off-cell size for adjusting the subscriber station internal timing signal generator. 12. The subscriber station processing means of claim 10, wherein subscriber station processing means are calculated to adjust the subscriber station internal timing signal generator after a predetermined duration when the predetermined number of processed off-cell sizes is not within the tolerance of the calculated average off-cell size. A subscriber communication system, characterized by providing an average off-cell size. Each base station includes a plurality of base stations, each base station in each network being selectively communicated with a plurality of subscriber stations, through one Radio Control Channel (RCC) from a plurality of scheduled frequencies to one frequency selected by the base station. Means for transmitting control information to the subscriber station, the voice data signal via an assigned channel between the line appearance connecting the base station to the central office and the line connection connecting the subscriber station to the subscriber terminal at the base station Each base station is connected to the above-described channel line appearance to provide an allocated channel for communicating voice data signals between the line appearance and the subscriber station, and the voice data signal between the line connection and the base station is transmitted. Each subscriber with one line connection to provide one assigned channel by communicating Presentations are connected, and a subscriber communication system characterized in that it comprises a line appearance with the means for processing the DC signal information for communication over the assigned channel between the line connection. 13. The apparatus of claim 12, wherein the processing means means for detecting DC signal information at the line appearance and / or the line connection, and determining the condition of the detected DC signal information for communication over the assigned channel on behalf of the voice data signal. And means for the subscriber communication system. 15. The apparatus of claim 13, wherein the voice data signal is communicated via an assigned channel in the signal burst, and means for detecting DC signal information in the line connection comprises at the subscriber station for monitoring the signal in the line connection; Means in a subscriber station for buffering the monitored signal, and means in a subscriber station for processing the buffered signal for detecting DC signal information, and means for defining conditions of the detected DC signal information, as described above. Means in the subscriber station for transmitting the detected DC signal information via the assigned channel as a control block in a control-signal burst having the same format as in one voice-data-signal burst. Subscriber communication system. 15. The control block of claim 14, wherein the control block includes a flag pattern identifying the block as one control block, and one control block in one signal burst received from the subscriber station over the assigned channel by the base station recognizing the flag pattern. Means for determining if present, means for responding to recognition of a flag pattern for reformatting the DC signal information in the control block in a standard DC signal control information format for delivery to a slower appearance. system. 14. A means according to claim 13, wherein the voice data signal is communicated via an assigned channel in the signal buster, and means for detecting DC signal information at the line outlet is a means in the base station for monitoring the signal at the line outlet. Means in the base station for buffering the decoded signal, and means in the base station for processing the buffered signal in order to detect DC signal information, and means for determining conditions of the detected DC signal information. And means in the base station for transmitting the detected DC signal information to the subscriber station via the assigned channel as a control block in a control signal burst having the same format as in the data-signal burst. 17. The control block of claim 16, wherein the control block includes a flag pattern that identifies the block as one control block, and one control block in one signal burst received from the subscriber station over the assigned channel by the base station recognizing the flag pattern. Means for determining if present, means for responding to recognition of a flag pattern for reformatting DC signal information in a control block in a standard DC signal information format for delivery to a track appearance. .

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