JPS6190544A - Duplex transmission method and device by simplex radio channel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to techniques for achieving duplex transmission on a single radio channel. In particular, the invention relates to a simplex arrangement for realizing duplex operation in which a channel is shared in time between two users and the active user has priority in terms of the average bit rate transmitted.

DESCRIPTION OF THE PRIOR ART Bidirectional wireless communication is realized either by using separate channels for each direction of transmission (duplex) or by using a one-channel, but-to-talk technique (simplex). The problem is that duplex approaches require two radio frequency (RF) channels, and simplex approaches make it virtually impossible to receive while transmitting.

Eastmond on July 19, 1977 (B, C, E
U.S. Pat. No. 4,037,158 to Astmond discloses a bidirectional FM radio system that operates on a single channel and simulates duplex operation. Here, a bidirectional FM transceiver operates on a single channel and automatically samples the channel to detect the presence of a carrier. When the transmitter operates, it activates a timing means that generates a time interval, and at the end of the time interval the sample generator operates for a short time, turning off the transmitter and connecting the antenna to the receiver. A detector detects whether a carrier is present on the channel. When a carrier wave is detected, the detector output signal holds the transmitter off and operates the receiver to regenerate the received radio waves.

Proceedings of NTC78 held in Birmingham, Alabama, December 3-6, 1978, Volume 2, page 21.2.
1 to 21.2.7 Nielsen (P, T, N1el
sen)'s “A Digital Hybrid for Two-Wire Digital Subscriber Loops”
For Two-Wire Digital Subsc
The paper entitled ``Riber Loops'' discloses a digital hybrid that provides single-channel pulse code modulation (PCM) full-duplex transmission through an existing two-wire subscriber loop. The signal propagates in both directions simultaneously;
Occupying the same band, the separation of the two signals is achieved in the transceiver by an adaptive cancellation technique.

A remaining problem in the prior art is to provide a simplex device that achieves duplex operation, is economical to implement, and allows multiplexing of several users on a single channel.

According to the present invention, the aforementioned problems of the prior art are solved by a technique for realizing duplex transmission in a single radio channel.

Specifically, the present invention provides a simplex device for duplex operation where the channel is time-shared between two users and the active user has priority in the transmitted bit frequency.

According to a feature of the invention, duplex operation is performed in such a way that the channel is time-divided between the two users. In practice, a single active user receives most of the separate parts of the burst transmission period in both directions for its packet burst, while an inactive user produces a burst signal with only a section of transceiver control information. , which uses less than half of the burst transmission period in both directions. When both end users are active, each user transmits packets of information during separate halves of the transmission period in both directions, and the quality of the message signal is slightly degraded.

In accordance with one aspect of the invention, a transmitting and receiving transceiver is provided such that the transmitter and receiver communicate bidirectionally with a remote transceiver, each transceiver having a predetermined bidirectional transmission period. Send parsing of information between separate sections of. The transceiver (1): (a) transmits the associated local end user's digitally encoded message signal for transmission following the first section of the transmission period in both directions to the remote transceiver; (b) means for storing digital information in packets of information from each of the local end user and the remote transceiver during a second section of the bidirectional transmission period;

(2) means for detecting receipt of a digitally encoded message from each of the local end user and the remote transceiver and generating appropriate control signals; The frontage-to-cus transmitter transmits information for less than half, half, or more than half of the transmission time in both directions, depending on whether the transmitter is idle, both end users are active at the same time, or the remote end user is idle. and means for transmitting a burst of data.

According to another feature of the invention, during a predetermined bidirectional transmission period, the channel is time-shared between local and remote end users exchanging information, and the active one of the two Simplex apparatus for realizing duplex transmission in a single radio frequency channel such that each of the two users receives priority for the average bit frequency transmitted during separate portions of bidirectional transmission time selectively allocated to each of the two users. More specifically, if only one of two end users is active, that end user receives a greater portion of the two-way transmission time to send his message. If both end users are active at the same time, each receives half of the bidirectional transmission time. Furthermore, the simplex device allows a single radio channel to be time-multiplexed by several users, for example using techniques such as time-assigned audio interpolation (TASI).

Other features of the invention will become apparent during the course of the following description with reference to the drawings.

In the drawings, like numerals represent like components from several views.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the general concept for duplex transmission over a simplex channel in accordance with the present invention. At the transceiver position [A, the transceiver includes a transmit buffer and a receive buffer, which temporarily store samples of digitally encoded message signals to be transmitted and received, respectively, for a particular end user of the communication system. . Controller 12 of transceiver A (a) obtains information about the transmission activity of both the local end user and its associated remote end users; (b) function to provide timing signals for separately transmitting and receiving packet bursts of digital information over the simplex channel at appropriate times; At transceiver location B, transmit buffer 14, receive buffer 13 and controller 15 operate in a manner similar to that described for buffers 10 and 11 and controller 12.

Transmit buffers 10 and 14 are used to temporarily store digitally encoded message signal samples to be transmitted from the associated end users. next,
This information is assembled into packet bursts of information to be transmitted during predetermined portions of bidirectional transmission time to the associated remote transceivers under the control of controllers 12 and 15, respectively. Reception buffers 11 and 13 are (a) controllers 12 and 1, respectively.
5 to receive and temporarily store bursts of information destined for the relevant end user. (b) Associated Operates to read stored digital information from the buffer at a uniform frequency for transmission to a local end user.

For the case where transceiver B is a local transceiver and transceiver A is a remote transceiver when transmitting bursts of information through antennas 16 and 17,
Three transmission sequences are shown at different times, 2 and 3. At time t1, the sequence is shown in which the end user of transceiver A is idle and the end user of transceiver B is active.

Under these conditions, the burst of information from transceiver A to B only provides control information for the transceiver and, as will be explained below, is transmitted in less than half the bidirectional transmission period. In contrast, the transmission from transceiver B to A includes transceiver control information plus digitally encoded message information, which is transmitted over more than half the bidirectional transmission time.
At time t2, assume that the end user to transceiver is active and the end user of transceiver B is free. In such conditions, the opposite occurs at time t1, with the end user of transceiver A receiving more than half of the two-way transmission time to transmit information to transceiver B. At time t3, each of the end users of transceiver A and transceiver B are active at the same time, and in such conditions each end user has a two-way transmission period to transmit control and digitally encoded message information. half is received, but at this time the quality is slightly worse than when the message information is sent by only one end user, such as at times t1 and t.

FIG. 2 is a block diagram of a transceiver according to the invention that can be used as either transceiver A or B of FIG. In FIG. 2, signals from associated end users are received by user 20, which functions to convert analog input message signals from the end users into corresponding digitally encoded output signals. Therefore, the user 20 may, for example, use an analog/digital (A/
D) Can include any possible circuitry, such as a converter. It should be appreciated that if the signal from the associated end user is already in digitally encoded form, user 20 does not need to temporarily buffer the digitally encoded output signal from user 20. 10 and applied to the signal detector 21 at the same time. Signal detector 21 detects all end user activity (presence of digitally encoded signals) and generates an output signal to controller 12 indicating whether the associated local end user is active or idle. do.

Controller 12 determines end user activity at an associated remote transceiver, as described below with reference to the receiver section of FIG. The remote end user's activity then causes the controller 12 to determine the appropriate bit frequency to transmit the digitally encoded sample information stored in the transmit buffer 10 and place such an indication into the transceiver control information generator. . Transceiver control information generator 22 generates a start of message (SO
M) Functions to provide an indication of the primary and other necessary information including the transmission bit frequency of the associated message information to be transmitted towards the remote transceiver at the appropriate time.

The timing of the burst bit transmissions is determined by timing pulses from a clock 23 under control of controller 12.

During the transmission period of a burst of information to a remote transceiver, the clock 23 sends a first spring signal to the transmitting switch means 24 and connects the generator 22 to the transmitter 25, e.g. Immediately thereafter, the blocker 23 operates the transmit switch means 24 to connect it to the output of the bit removal circuit 26, providing transceiver control information including an indication of the transmitted bit frequency;
It operates according to control signals from controller 12 to receive digitally encoded sample messages stored in transmit buffer 10. The bit removal circuit 26 also (a) removes the transceiver control information section when the associated local end user is inactive and no message is stored in the transmit buffer 10, such as during time t1 in FIG. Later, without passing any bits from buffer 10, (b) when the local end user is active and the remote end user is free, as shown at time t2 in FIG. Passes the entire encoded message signal.

(c) Stored encoding to shorten the entire message signal in the transceiver control information section consisting of nine and a half normal bidirectional burst transmission periods when the local and remote end users are each operating simultaneously. Remove some of the lower order bits of the message signal sample. Again, control signals from controller 12 determine which of the above-described functions of bit removal circuit 26 are used during each burst interval to the remote transceiver.

In the receiving section of the transceiver of FIG.
will be received at the appropriate time. As discussed above, a burst may include (a) only transceiver control information and no message signals, (b) a transceiver control information section and an entire message signal, or (c) a transceiver control information section and a message at a reduced bit frequency. or a signal. (In case (c), certain lower order bits have been removed from each digitally encoded message signal sample.) At the beginning of the period of the received burst, the clock 23 is activated by the receiver switch means 31. and provides a transceiver control information section to the transceiver control information detector 32, which
and the bit frequency of the included message.

Controller 12 obtains this information from transceiver control information detector 32 . After receiving the transceiver control information, the clock 23 energizes the receive switch means 31 to
Arbitrary digitally encoded message information is read by the receiving server 11. The receive buffer 11 reads the stored digitally encoded information from the remote end user at a constant frequency during the received burst and provides it to the local end user through the decoder 33.

When a decoder is present, it operates in the opposite way to Korg 20. Even if the received digitally encoded message signal samples have been shortened by removing a predetermined lower order bit, the upper order bits represent the original value of each signal sample before the lower order bits are removed. Because it is a correct approximation of the amplitude, the analog signal samples generated from the received signal at decoder 33 are not slightly degraded in quality. Again, the controller 12 is operative to control the operation of the transmit section of the transceiver according to the transceiver control information received in bursts from the remote transceiver. Decoder 33 is not needed when the local end user can directly use the digitally encoded signal samples received from the remote end user in place of the decoded analog signal.

The operation of the controller 12 and system according to the present invention
A more complete understanding can be gained from the table shown in the figure and the associated sequence of bursts. In FIG. 3, the first four rows of the table show the different received bit frequencies when the local end user is indicated as free by the signal detector. In the first row of the table, the received transceiver control information is the received message bit frequency 11.
071, indicating that the remote end user is free and the received burst contains only transceiver control information. This condition is such that the burst sequence in Figure 3 is in the receiving section, and SOM and 11
The transceiver control information is shown as containing only the bit frequency indicating On. In the first row of the table, the signal detector 21 presents a 1"0" signal to the controller 12, indicating that the local end user is free and the transmit bit frequency is 1"'. This indicates that the digitally encoded signal of the entire message is sent through the bit removal circuit 26 without removing the lower bits.In the burst sequence on the right side of FIG. The frequency display is followed by a complete digitally encoded message sequence with no bits removed. Such received and transmitted sequences are free for the remote end user and free for the local end user. After the burst period, the buffer is just empty and the message bits are still 10.
This occurs most often when there are intermediate conditions where the data is stored and needs to be sent.

During the intermediate period after the last burst, while both end users are free, the controller 12 does not need to send the message bits as in the case shown in the first row of the table. operates to produce the second row of the sequence of tables. In the burst sequence shown on the right side of the second row, the far transceiver and the local transceiver have just finished transmitting the first and second transceiver control information sections, respectively, and each control section is connected to the SOM and I
Contains the bit frequency indicating IOII. In the third row of the table in Figure 3, the received burst has a transceiver control information section containing the SOM and the burst bit frequency of 111 I+, which is followed by a complete message, and the message bits are sent to the far transceiver. Indicates that there is no The sequence of bursts for the far and local transceivers under these conditions is shown on the right side of the third row.

The fourth row of the table and the burst sequence of FIG. transceiver. Under such conditions, the received burst contains a transceiver control information section and a half-frequency digitally encoded message, and the received digitally encoded message signal sample has some of its lower order bits. It is shown that it has been removed by the bit removal circuit 26 of the remote transceiver. As previously mentioned, such signals are presented in a slightly degraded form to local end users. The state shown in line 4 of FIG. 3 is a transient state in which the local and remote end users are active until the last burst transmission, after which the local end user becomes free. Such a state continues for one burst period, and the state shown in the fifth line of FIG. 3 occurs first.

In the fifth row of the table and the burst sequence in Figure 3, the received burst from the far transceiver is
This indicates to the local controller 12 that the remote end user is free and the received burst contains no message bits, but the local end user is active. It is detected that the local controller 12
allows the transmission of the transceiver control information section and the entire message signal during the transmission burst.

This condition is illustrated in the burst sequence on the right side of the fifth line.

The sixth row of the table and burst sequence in FIG. 3 shows a transient burst sequence that does not continue for more than one bust period until the sequence changes to the seventh row of the table and burst sequence in FIG. In line 6, the received burst contains the SOM and a bit frequency indication of "1", the control information section is followed by the reception of the entire message signal, and the local end user is digitally encoded in buffer 1o. It indicates that the message is stored and active and should be sent to the remote transceiver. As shown in the associated burst sequence in line 6 of FIG. 3, the received burst includes transceiver control information and the entire message sequence;
Presumably the local end user is previously idle and no message bits were sent in the previous burst, for example as shown in the third row of the table. but,
From that burst sequence, the local end user becomes active and stores the bits of the message in the local transmit buffer IO for transmission to the distant end user. Therefore, the controller 12 operates the control information generator 22 of the local transceiver to
M and 172 bit frequency representations are transmitted and the stored message bits are transmitted at full speed without extending the burst period. As a result, the local message bits are sent through a bit removal circuit 26 which removes some of the lower order bits and sends out a slightly degraded message.

Line 7 of the table of FIG. 3 and the burst sequence shows the case where both end users are active at the same time. This is probably the condition for the next burst shown in line 6 of the table above. Under such conditions, each received burst and transmitted burst contains a message with the transceiver control section containing a bit frequency indication indicating SOM and 1/2 and some of its lower order bits removed. . This sequence continues until one of the end users becomes free, as shown in the 3rd or 5th row of the table in Figure 3, and an intermediate condition occurs as shown in the 4th row. .

The techniques described above relate to the transmission of bursts of information between two separate transceivers of a communication system for duplex transmission in a simplex device according to the present invention. The technique also uses time-allocated voice interpolation (e.g., between a base station transceiver and multiple distant transceivers) through a simplex channel.
It can be expanded to communicate using TASI technology. TASI is a well-known communication technology.In some devices, a central TASI controller (not shown)
regularly controls the time of transmission of each of the transceivers of the system according to the activity of each end user or pair of end users. In the configuration shown here, the central T
Control of the individual transceivers from the ASI controller is carried out by a central TASI controller informing each of the controllers 12 of each transceiver of its burst time according to a time-shared sequence as representatively shown in FIG. . Similarly, controller 1
2 informs the central TAS I controller about the detected activities of the relevant end users and
Obtain an appropriate schedule from the ASI controller and request burst time allocation from end users that are active at the time.

In FIG. 4, a first transmission period is used to transmit from a mobile station to a base station for an active pair of end users using a single channel. Immediately following the first transmission period is a second transmission period in which a second transmission period is shown from the base station to the mobile station between the same active pair of end users using a single channel. has been done. It is assumed that four active pairs of end users (A-D) use the channel. As shown in FIG. 4, during the first transmission period, the pair of transceivers A-11)
Transmissions from the mobile station to the base station occur sequentially, followed by transmissions from the base station to the mobile station for the same transceiver pair. From the lengths of bidirectional transmissions in Figure 4, (a) the bidirectional transmissions for transceiver pairs A and C reflect the burst sequence in Figure 3 and the conditions shown in the third row of the table; Only the mobile station side is active. (b) The bidirectional transmission of transceiver pair 13 reflects the burst sequence of FIG. 5 and the conditions shown in row 7 of the table, where both end users are active.

(c) Bidirectional transmission for transceiver pairs reflects the table of FIG. 3 and the case of row 5 of the burst sequence, with the base station end user being the only active end user in the D pair.

The bit removal circuit 26 described herein may be any device as long as it achieves this function. For example, when reading each stored message word of an information burst from buffer 10, gating devices including separate AND gates for each message word read from buffer 10 in parallel and provide information from buffer 10 to the output bus.

Each AND gate is responsive to a separate control signal from controller 12 to de-energize or energize the AND gate as a whole, allowing a parallel output signal containing all of a given 'l' or read bit. To serially transmit the parallel bits of , a deserialization device such as a shift register can be used, and such devices are well known to those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the general concept of the invention providing duplex operation on a simplex wireless channel; FIG. 2 is a block diagram of a transceiver according to the invention providing duplex operation on a simplex channel; FIG. For each possible combination of operation on a simplex wireless channel according to the invention of the transceiver of FIG. 2, the various possible end-user activity combinations and the associated bidirectional transmission of packet burst information between two end users. FIG. 4 is a diagram of the timing sequence of a bidirectional burst of information between multiple mobile stations and a fixed station using a TASI-like environment. [Explanation of symbols of main parts] Transmission buffer・・・・・・・・・・・・・・・・・・
...10,14 reception buffer...
・・・・・・・・・・・・11.13 Controller・
・・・・・・・・・・・・・・・・・・・・・12,
15 Transmitter・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・25 Receiver・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・30
Applicant: American Telephone & Telegraph
Campany

Claims (1)

Claims: 1. A receiver that receives a burst of digitally encoded information destined for a local end user from a remote transceiver over a simplex channel during a first predetermined time period; In a transceiver including a transmitter capable of transmitting digitally encoded information from a local end user of the transceiver to a remote transceiver over a simplex channel during a second predetermined period of time, the transceiver includes: (a) information transmitted by the transmitter; (b) detecting the receipt of a digitally encoded message intended for the local end user in a burst of information on a simplex channel; and means for generating a control signal indicative of each such reception; in response to the control signal from the detection and generation means: (a) the control signal from the detection and generation means indicates that the local end user is inactive; operate the transmitter to transmit only the digital control information to the distant transceiver in the next burst of information when the digitally encoded message indicates that it will not be transmitted during the next burst of information. and (b) the control signal from the detection and generation means indicates that during the first period no digitally encoded message is received in the burst of information to the local end user and the digitally encoded message is operate the transmitter to transmit both digital control information and message signals in digitally encoded form from the local end user to the distant transceiver when indicated to be transmitted during bursts of ( c.
) a control signal from the detection and generation means indicates receipt of a digitally encoded message signal from a local end user during a first period; a control signal from a local end user during a second period such that a predetermined lower bit of the digitally encoded message signal is removed therefrom when indicating that it is to be transmitted from a user; and control means for co-transmitting digitally encoded message signals. 2. The transceiver of claim 1, wherein the first and second time periods are consecutive, providing time-shared bidirectional transmission over a simplex channel. 3. A transceiver as claimed in claim 1 or 2, wherein the transceiver further comprises: (b) a digitally encoded message signal received from the receiver in a burst of information from a distant transceiver during a first time period and then to be transmitted to a local end user; means capable of temporarily storing encoded message signals. 4. A transceiver according to claim 1 or 2, wherein the transceiver further comprises means capable of generating digital control information to be included in the transmission burst of information, the control information comprising message start information and bits. the bit frequency information includes: (a) a first code when the burst of information to be transmitted does not include a digitally encoded message signal;
(b) a second code when transmitting intact the digitally encoded message signal received from the local end user during the burst of information; and (c) a second code when transmitting the digitally encoded message signal received from the local end user during the burst of information. 1. A transceiver, wherein the transceiver includes a third code when transmitting a message signal with its lower bits removed. 5. A transceiver as claimed in claim 4, wherein the detection and generation means are responsive to bit frequency information in the control information portion of the received burst of information;
(a) a first control signal when the digitally encoded message signal is not included in the received burst of information; (b) the digitally encoded message signal is received without removing lower order bits therefrom; (c) when the digitally encoded message signal is included in the received burst of information by removing a predetermined lower order bit therefrom; A transceiver, characterized in that the transceiver generates a third control signal when the transceiver is activated. 6. The transceiver according to claim 5, wherein the transceiver further comprises: detecting and generating means for controlling the remote transceiver during the first time period in response to either a second or a third control signal from the detection and generation means; A transceiver comprising decoding means for generating analog signal samples at a uniform predetermined frequency corresponding to digitally encoded signal samples of a digitally encoded message signal in a burst of information from the transceiver. 7. The transceiver of claim 1, wherein the controller means is further responsive to control signals from the central system controller to operate the transceiver to select the associated end in a third period of time. a plurality of X transceivers operative to receive a burst of information destined for the user, the third period being a plurality of X transceivers used for separate first direction communications between the plurality of X transceivers and the base station transceiver transmitting a burst of information destined for a distant transceiver in a selectively assigned fourth period comprising A second end user between a base station transceiver and a plurality of
A transceiver comprising a plurality of X sequential time periods used for communication in the direction of. 8. The transceiver of claim 7, wherein the controller means includes: (a) detection and generation means for transmitting output control signals indicative of associated local and remote end user activity to a central system controller; , (b) a transceiver responsive to control signals from both a central system controller that causes the transceiver to cease transmitting and receiving bursts of information when both associated local and remote end users are inactive. 9. A method for duplex transmission over a simplex wireless channel, the method comprising: (a) receiving at a local transceiver a digitally encoded burst of information from a distant transceiver during a first period; whether a digitally encoded message signal section is present in the burst of information and whether the included digitally encoded message signal is transmitted to the remote end user in a first form as received from the remote end user; a second form in which a predetermined lower order bit is removed from a message word in a digitally encoded message signal transmitted by a transceiver or received from a remote end user; (b) from the control information section in the burst received in step (a) an indication of (1) the presence or absence of a digitally encoded message signal in the burst of information;
2) detecting the manner in which the contained message signals were respectively transmitted from the distant transceiver and generating from this a control signal representative of such detection; and (c) causing a local end user connected to the local transceiver to detecting whether a message signal is being transmitted and generating a control signal indicative of such detection; and (d) in response to the control signals from steps (b) and (c), transmitting a second burst of information. During the period of
(1) control information sections only when the digitally encoded message signal from which the control signals from steps (b) and (c) are received has a first form and the local end user is inactive; ) The control signals from steps (b) and (c) are not present in the control information section when there is no digitally encoded message signal during the received burst of information and indicate that the local end user is active. (3) a digitally encoded message signal in the first form as received from the local end user; and (3) a second form during the burst of information in which the control signals from steps (b) and (c) are received. a second form of digitally encoded message signal with the control information section and predetermined lower bits removed when indicating that the local end user is active; A method for carrying out duplex transmission, characterized in that a burst of information containing a message is sent. 10. The method of claim 9, further comprising: (e) in performing steps (a) and (d), immediately before transmitting the burst of information in step (d), step (a) 1. A method for performing duplex transmission, comprising: receiving a burst of information during a first period of time. 11. The method of claim 9, wherein the local transceiver communicates with a plurality of remote transceivers through a simplex wireless channel, and (e) performing step (c) at the local transceiver and each of the plurality of remote transceivers. (f) when control signals from the local transceiver and the remote transceiver indicate that any associated end user is active; From the central system controller to each local transceiver and multiple remote transceivers (1
) a third period in which each distant transceiver separately transmits a burst of information to the local transceiver during the first discrete period; and (2) a second period of time. (g) transmitting separate control signals indicative of a fourth period during which the local transceiver sends back separate bursts of information to each remote transceiver; performing steps (a) to (d) for bidirectional transmission between the local transceiver and the plurality of far transceivers according to the control signal transmitted in step (f) to the plurality of far transceivers; , a method for performing duplex transmission, comprising the steps of: