Communication system and a central processing unit as well as a communication station in the communication system

• US 5,239,543 A
• Filed: 11/04/1991
• Issued: 08/24/1993
• Est. Priority Date: 11/05/1990
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Janssens, Abraham
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US07/788,107
• Time in Patent Office: 659 Days
• Field of Search: 381/77, 381/80, 381/81, 370/77, 370/79, 370/80, 370/82, 370/95.1, 370/99, 370/105.1
• US Class Current: 370/458
• CPC Class Codes: H04M 9/025 Time division multiplex systems, e.g. loop systems

Abstract

A communication system comprises a central processing unit (1) and a plurality of N communication stations (2.1, 2.2, . . . , 2N), in which the central processing unit and the communication stations are coupled over an uplink signal line (3) and a downlink signal line (4). The downlink signal (FIG. 3) on the downlink signal line has the form of successive frames, each frame comprising M signal blocks (SB_m), the first signal block in a frame comprising a synchronizing word (sync word) (22), the signal blocks all having space for storing audio information in the form of p audio words (21), the M-1 signal blocks not comprising a sync word further having space for storing control information, the control information in a signal block belonging to a communication station containing downlink assign information (a.dl+m) denoting which audio words in the signal blocks in a frame are destined for said communication station. The uplink signal (FIG. 4) has the form of successive frames having a time duration equal to the time duration of the frames in the downlink signal. Each frame has space for first signal blocks (30) each comprising two or more audio words, and second signal blocks (31) comprising control information. The control information in the downlink signal and destined for a station further includes uplink assign information (audio chan. upl+m) denoting what first signal blocks in a frame in the uplink signal originate from a station. Furthermore, there are gaps (36A) between the uplink signal blocks originating from different stations.

Claims

1. A method for communicating in a communication system which includes a central processing unit and a number, N, of communication stations, where N≧

2, the method including the steps of

a) transmitting a downlink signal from the central processing unit to the communication stations on a downlink channel, the downlink signal having the form of successive frames, each frame having space for accommodating M signal blocks, the signal blocks each having space for accommodating audio information in the form of p respective audio words per signal block, the signal blocks including

i) a first signal block including a synchronizing (sync) word, and

ii) M-1 signal blocks, not including a the synchronizing word, having space for accommodating control information, the control information corresponding to a respective one of the communication stations, the control information being accommodated in a signal block comprising

A) downlink assign information denoting which audio words, of the p audio words in each signal block in a frame, are destined for the respective one of the communication stations; and

B) uplink assign information denoting which first signal block or blocks in a frame in an uplink signal are coming from the respective one of the communication stations

b) transmitting the uplink signal from the communication stations to the central processing unit on an uplink channel which is separate from the downlink channel, the uplink signal having the form of successive frames, each frame having a time duration substantially equal to the time duration of the frames in the downlink signal, each frame having space for accommodating

i) the first signal blocks, each first signal block having space for accommodating a number of audio words greater than one, and

ii) second signal blocks, each second signal block having space for accommodating control information, signal blocks in the uplink signal coming from different communication stations being separated by gaps not containing any information.

2. Method as claimed in claim 1, characterized in that

the signal blocks in the downlink signal each have space for accommodating r data words,

the downlink assign information further denotes which data words of the r data words in the signal blocks in a frame are destined for the respective one of the communication stations,

each frame in the uplink signal has space for accommodating third signal blocks, each third signal block having space for accommodating a number of data words greater than one, and

the uplink assign information further contains information denoting which third signal block or blocks in a frame in the uplink signal are coming from the respective one of the communication stations.

3. Method as claimed in claim 1, characterized in that each frame in the uplink signal comprises a time slot for communication station'"'"'s initialize signal during an initializing phase of the communication station to be initialized, the time duration of the time slot exceeding that of the initialize signal.

4. Method as claimed in claim 3, characterized in that the first signal block in a frame in the downlink signal in said initializing phase has space for time equalization information and address information, the address information being intended for the communication station to be initialized and denoting the communication station for which the time equalization information is destined.

5. Method as claimed in claim 4, wherein the time slot is the same as the space for accommodating control information.

6. Method as claimed in claim 5, characterized in that the control information in a signal block in the downlink signal belonging to a communication station may comprise time shift information for this communication station, which time shift information is intended for correcting the time equalization information.

7. Method as claimed in claim 3, wherein the time slot is the same as the space for accommodating control information.

8. Method as claimed in claim 4, characterized in that the address information applied during the initializing phase to a communication station to be initialized, denotes which second signal block in a frame in the uplink signal comes from said communication station.

9. A method for operating a central processing unit in a communication system which includes a number, N, of communication stations, where N≧

2, the method including the steps of

a) transmitting a downlink signal to the communication stations on a downlink channel, the downlink signal having the form of successive frames, each frame having space for accommodating M signal blocks, the signal blocks each having space for accommodating audio information in the form of p respective audio words per signal block, the signal blocks including

i) a first signal block including a synchronizing (sync) word, and

ii) M-1 signal blocks, not including a the synchronizing word, having space for accommodating control information, the control information corresponding to a respective one of the communication stations, the control information being accommodated in a signal block comprising

A) downlink assign information denoting which audio words, of the p audio words in each signal block in a frame, are destined for the respective one of the communication stations; and

B) uplink assign information denoting which first signal block or blocks in a frame in an uplink signal are coming from the respective one of the communication stations

b) receiving the uplink signal from the communication stations on an uplink channel which is separate from the downlink channel, the uplink signal having the form of successive frames, each frame having a time duration substantially equal to the time duration of the frames in the downlink signal, each frame having space for accommodating

i) the first signal blocks, each first signal block having space for accommodating a number of audio words greater than one, and

ii) second signal blocks, each second signal block having space for accommodating control information;

signal blocks in the uplink signal coming from different communication stations being separated by gaps not containing any information;

c) extracting the first signal blocks in a frame coming from a first communication station from at least one first substantially fixed position in the successive frames in the uplink signal, said first fixed position or positions being related to the uplink assign information belonging to the first communication station; and

d) the transmitting step including applying the audio words of the first signal blocks coming from the first communication station to a second communication station, said applying including inserting a successive audio word in at least one second fixed position in the successive blocks of a frame in the downlink signal, said second fixed position or positions being related to the downlink assign information for the second communication station.

10. Method as claimed in claim 9, wherein

the signal blocks in the downlink signal each have space for accommodating r data words,

the downlink assign information further denotes which data words of the r data words in the signal blocks in a frame are destined for the respective one of the communication station,

each frame in the uplink signal has space for accommodating third signal blocks, each third signal block having space for accommodating a number of data words greater than one,

the uplink assign information further contains information denoting which third signal block or blocks in a frame in the uplink signal are coming from the respective one of the communication stations,

the method further comprising the steps of:

for the supply of data words from the central processing unit to the second communication station, inserting a successive data word at least at one fixed position in in a frame in the downlink signal, and

generating downlink assign information denoting which data words in the signal blocks of the frame are destined for the second communication station, the fixed position(s) of a (the) data word(s) in a signal block being related to said downlink assign information for the second communication station.

11. Method as claimed in claim 10, further comprising the steps of:

for causing transmission of data words from the first communication station to the central processing unit, generating uplink assign information belonging to said first communication station, which assign information further denotes which third signal block, containing a number of data words greater than one, in a frame in the uplink signal is coming from this first communication station, and

extracting the third signal block coming from said first communication station from a frame in the uplink signal in correspondence with the uplink assign information.

12. Method as claimed in claim 9, wherein each frame in the uplink signal comprises a time slot for a communication station'"'"'s initialize signal during an initializing phase of the communication station to be initialized, the time duration of the time slot exceeding that of the initialize signal, the method further comprising the steps of:

for initializing a communication station, generating and supplying to the downlink signal an initialize start signal for subsequently detecting an initialize signal in the time slot of a frame in the uplink signal, and for detecting a second instant at which the initialize signal is received relative to a first instant at which the initialize start signal is transmitted,

for calculating, from second instant, time equalization information, which time equalization information is related to the distance of the uplink signal transmission path between the central processing unit and said communication station, and

supplying an assign signal, address information and said time equalization information in a first signal block in a frame in the downlink signal.

13. Method as claimed in claim 12, further comprising the step of extracting one of the second signal blocks in the uplink signal, which one of the second signal blocks is coming from the first communication station and is located at a third substantially fixed position in the frame, said third fixed position being related to the address information applied to the first communication station during the initializing phase of this communication station.

14. The method of claim 12 further comprising the steps of generating a control signal as a function of a difference between the second instant and a desired receive instant of the initialize signal;

transmitting the control signal as time shift information in one of the second signal blocks of the downlink signal, which one second signal block corresponds to the communication signal to be initialized.

15. A method for operating a communication station in a communication system which includes a central processing unit and a number, N, of communication stations, where N≧

2, the method including the steps of

a) receiving a downlink signal from the central processing unit on a downlink channel, the downlink signal having the form of successive frames, each frame having space for accommodating M signal blocks, the signal blocks each having space for accommodating audio information in the form of p respective audio words per signal block, the signal blocks including

i) a first signal block including a synchronizing (sync) word, and

ii) M-1 signal blocks, not including a the synchronizing word, having space for accommodating control information, the control information in at least one of the M-1 signal blocks corresponding to the communication station and comprising

A) downlink assign information denoting which audio words, of the p audio words in that signal block or blocks, are destined for the communication station; and

B) uplink assign information denoting which first signal block or blocks in a frame in an uplink signal are to come from the communication station;

b) extracting control information belonging to the communication station from the downlink signal;

c) extracting from the control information the downlink assign information and the uplink assign information for the communication station;

d) extracting an audio word from at least one fixed frame position in the downlink signal based on the downlink assign information;

e) transmitting portions of the uplink signal to the central processing unit on an uplink channel which is separate from the downlink channel, the uplink signal having the form of successive frames, each frame having a time duration substantially equal to the time duration of the frames in the downlink signal, each frame having space for accommodating

i) the first signal blocks, each first signal block having space for accommodating a number of audio words greater than one, and

ii) second signal blocks, each second signal block having space for accommodating control information, signal blocks in the uplink signal coming from different communication stations being separated by gaps not containing any information, the transmitting step including supplying at least one first signal block containing audio words and a second signal block containing control information at least one substantially fixed second frame position the in the uplink signal, the second frame position resulting from the uplink assign information.

16. Method as claimed in claim 15, in wherein

the signal blocks in the downlink signal each have space for accommodating r data words,

the downlink assign information further denotes which data words of the r data words in the signal blocks in a frame are destined for said communication station,

each frame in the uplink signal has space for accommodating third signal blocks, each third signal block having space for accommodating a number of data words greater than one,

the uplink assign information further contains information denoting which third signal block or blocks in a frame in the uplink signal are coming from said communication station,

the method further comprising the step of, for sending data words from the communication station to the central processing unit supplying the third signal block containing data words in the uplink signal at a frame position related to the uplink assign information for said communication station.

17. Method as claimed in claim 16, further comprising for receiving data words from the central processing unit, extracting a successive data word from at least one fixed frame position related to said downlink information for said communication station.

18. The method of claim 16, wherein the first signal block in a frame in the downlink signal in an initialization phase has space for equalization and address information intended for the communication station;

and further comprising the steps of,

during the initialization phase, supplying an initialization signal in the space for accommodating control information in one of the second signal blocks of the uplink signal, if the control information of the communication station has not changed during one or more previous frames;

detecting time shift information in the control information belonging to the communication station in a signal block in the downlink signal;

advancing or just delaying the instant at which the first, second, and third signal blocks are supplied to the uplink signal in response to the time shift information.

19. Method as claimed in claim 15, wherein each frame in the uplink signal comprises a time slot for a communication station'"'"'s initialize signal during an initializing phase of the communication station, the time duration of the time slot exceeding that of the initialize signal, the method further comprising

for initializing the communication station, detecting an initialize start signal in the downlink signal,

subsequently generating an initialize signal and supplying the initialize signal in the uplink signal at an instant so that the initialize signal is located in the time slot of a frame in the uplink signal,

detecting an assign signal, address information and time equalization information in the first signal block in a frame in the downlink signal.

20. Method as claimed in claim 19, further comprising supplying the first and second signal blocks in the uplink signal in response to the time equalization information at an instant so that the first and second signal blocks of the uplink signal supplied to the uplink signal by the communication station are separated from uplink signal blocks supplied by different communication stations by gaps not containing any information.

21. Method as claimed in claim 20, further comprising supplying the third signal blocks to the uplink signal in response to the time equalization information at an instant so that the third signal blocks in the uplink signal supplied to the uplink signal by the communication station are separated from uplink signal blocks supplied by different communication stations by gaps not containing any information.

22. The method of claim 15

wherein the first signal block in a frame in the downlink signal in an initialization phase has space for equalization and address information intended for the communication station;

further comprising the step of, during the initialization phase, supplying an initialization signal in the space for accommodating control information in one of the second signal blocks of the uplink signal, if the control information of the communication station has not changed during one or more previous frames.

23. Method as claimed in claim 22, further comprising the steps of:

detecting time shift information in the control information belonging to the communication station in a signal block in the downlink signal, and

advancing or just delaying the instant at which the first and second signal blocks are supplied to the uplink signal in response to the time shift information.

24. Method as claimed in claim 22 wherein said second frame position is related to the address information.

25. A method for operating a communication station in a communication system which includes a central processing unit and a number, N, of communication stations, where N≧

2, the method including the steps of

a) receiving a downlink signal from the central processing unit on a downlink channel, the downlink signal having the form of successive frames, each frame having space for accommodating M signal blocks, the signal blocks each having space for accommodating audio information in the form of p respective audio words per signal block, the signal blocks including

i) a first signal block including a synchronizing (sync) word, and

ii) M-l signal blocks, not including a the synchronizing word, having space for accommodating control information, the control information in at least one of the M-1 signal blocks corresponding to the communication station and comprising

A) downlink assign information denoting which audio words, of the p audio words in that signal block or blocks, are destined for the communication station; and

B) uplink assign information denoting which first signal block or blocks in a frame in an uplink signal are to come from the communication station;

b) extracting control information belonging to the communication station from the downlink signal;

c) extracting from the control information the downlink assign information for the communication station;

d) extracting an audio word from at least one fixed frame position in the downlink signal based on the downlink assign information;

e) transmitting portions of the uplink signal to the central processing unit on an uplink channel which is separate from the downlink channel, the uplink signal having the form of successive frames, each frame having a time duration substantially equal to the time duration of the frames in the downlink signal, each frame having space for accommodating

i) the first signal blocks, each first signal block having space for accommodating a number of audio words greater than one, and

ii) second signal blocks, each second signal block having space for accommodating control information, signal blocks in the uplink signal coming from different communication stations being separated by gaps not containing any information.