Wireless communication system

• US 6,026,082 A
• Filed: 11/27/1996
• Issued: 02/15/2000
• Est. Priority Date: 11/27/1996
• Status: Expired due to Fees

• Current Assignee: Action Grindelwald LLC (Intellectual Ventures LLC)
• Original Assignee: Telergy, Inc. (Crown Castle International Corporation)
• Inventors: Astrin, Arthur W.
• Primary Examiner(s): VU, HUY DUY
• Application Number:
  US08/758,597
• Time in Patent Office: 1,175 Days
• Field of Search: 370/468, 370/433, 370/465, 370/329, 370/431, 455/452
• US Class Current: 370/336
• CPC Class Codes: H04M 3/56 Arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities video conference systems H04N7/15
• CPC Class Codes: H04M 3/561 by multiplexing
• CPC Class Codes: H04M 3/569 using the instant speaker's algorithm speech detection per se G10L25/78
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365

Abstract

A wireless communications system includes a base station and a plurality of terminal units which can be mobile. The base station establishes connections among sets of two or more of the mobile units so as to permit private, full-duplex conversations to take place within each set of terminal units. A number of such conversations can take place concurrently. The base station allocates packet time slots for each active terminal unit to transmit, and dynamically reduces the allocation per terminal unit only as the number of active terminal units increases. The terminal units are able to transmit the same isochronous information (such as voice) regardless of the number of packet time slots allocated to the terminal unit, by compressing the data by a greater amount when fewer packet slots are allocated, and by a lesser amount when a greater number of packet slots are allocated per unit of time. The system is able to support a range of numbers of concurrent conversations, while dynamically maximizing the quality of such communications at different times.

Claims

1. A method for operating a system having a plurality of terminal units each having an active and an inactive state with respect to a time multiplexed communications medium, said system further including a control unit, comprising the steps of:

allocating, when a number N_A of said terminal units are active, an amount of time T_A,i per unit time for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units, said control unit transmitting, via said communications medium, indications of said amounts of time T_A,i for each of said active units;

said control unit receiving, via said communications medium, requests from at least one of said terminal units for at least k of said inactive terminal units to become active;

said control unit transmitting an approval of said requests via said communications medium; and

allocating, when a number N_B of said terminal units are active, N_B =N_A +k, an amount of time T_B,i per unit time for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units, said control unit transmitting, via said communications medium, indications of said amounts of time T_B,i for each of said active units,

wherein T_B,i <

T_A,i for at least a first one of said active terminal units.

3. A method according to claim 1, wherein said communications medium comprises a wireless communications medium.

4. A method according to claim 1, wherein said first active terminal unit transmits isochronous data both when allocated T_A,1 per unit time and when allocated T_B,1 per unit time.

5. A method according to claim 1, further comprising a step of allocating, when a number N_C of said terminal units are active, an amount of time T_C,i per unit time for transmission via said communications medium by each respective i'"'"'th one of said active terminal units, N_C >

N_B,

wherein T_C,i <

T_B,i for at least one of said active terminal units.

6. A method according to claim 1, wherein said communications medium operates in temporally sequential frames during a subject time period,

wherein said step of allocating an amount of time T_A,i comprises a step of allocating a number S_A,i of time slots in each of said frames for transmission via said communications medium by each respective i'"'"'th one of said active terminal units,

and wherein said step of allocating an amount of time T_B,i comprises a step of allocating a number S_B,i of time slots in each of said frames for transmission via said communications medium by each respective i'"'"'th one of said active terminal units.

7. A method according to claim 6, wherein all of said time slots have equal duration.

8. A method according to claim 6, wherein each of said frames is divided into a plurality of sub-frames, and wherein said step of allocating S_A,i time slots in each of said frames comprises a step of allocating one time slot per sub-frame for a second one of said active terminal units.

9. A method according to claim 8, wherein said step of allocating S_B,i time slots in each of said frames comprises a step of allocating one time slot per two sub-frames for said second active terminal unit.

18. A method according to claim 6, further comprising the step of a second one of said active terminal units transmitting via said communications medium during one of the time slots allocated to said second active terminal unit.

19. A method according to claim 6, wherein said system further includes a control unit, further comprising the step of allocating an outbound portion in each of said frames for transmission via said communications medium by said control unit.

25. A method according to claim 1, wherein one of said terminal units is a repeater.

2. A method for operating a system having a plurality of terminal units each having an active and an inactive state with respect to a time multiplexed communications medium, said system further having a control unit, comprising the steps of:

allocating, when a number N_A of said terminal units are active, an amount of time T_A,i per unit time for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units;

allocating an amount of time T_A,b per unit time for transmissions by said control unit via said communications medium when N_A of said terminal units are active;

allocating, when a number N_B of said terminal units are active, N_B >

N_A, an amount of time T_B,i per unit time for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units, and

allocating an amount of time T_B,b per unit time for transmissions by said control unit via said communications medium when N_B of said terminal units are active,

wherein T_B,i <

T_A,i for at least a first one of said active terminal units, and wherein T_A,b =T_B,b.

10. A method for operating a system having a plurality of terminal units each having an active and an inactive state with respect to a time multiplexed communications medium operating in temporally sequential equal duration frames during a subject time period, comprising the steps of:

allocating, when a number N_A of said terminal units are active, an amount of time T_A,i per unit time for transmission via said communications medium by each respective i'"'"'th one of said active terminal units; and

allocating, when a number N_B of said terminal units are active, N_B >

N_A, an amount of time T_B,i per unit time for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units,

wherein T_B,i <

T_A,i for at least a first one of said terminal units,

wherein said step of allocating an amount of time T_A,i comprises a step of allocating a number S_A,i of time slots in each of said frames for transmission via said communications medium by each respective i'"'"'th one of said active terminal units,

and wherein said step of allocating an amount of time T_B,i comprises a step of allocating a number S_B,i of time slots in each of said frames for transmission via said communications medium by each respective i'"'"'th one of said active terminal units,

wherein each of said time slots has equal duration, said first active terminal unit transmitting via said communications medium at a rate of B bits per time slot, S_A,1 time slots per frame being allocated to said first active terminal unit when N_A terminal units are active, and S_B,1 time slots per frame being allocated to said first terminal unit when N_B terminal units are active, further comprising the steps of said first active terminal unit;

producing first output data at a rate R_A,1 bits per frame in response to first isochronous input data, while S_A,1 time slots per frame are allocated to said first terminal unit, B*S_B,1 <

R_A,1 ≦

B*S_A,1 ;

compressing said first isochronous input data to produce said first output data at a rate R_B,1 bits per frame while S_B,1 time slots per frame are allocated to said first active terminal unit R_B,1 ≦

B*S_B,1 ; and

transmitting said first output data via said communications medium during time slots allocated to said first active terminal unit.

11. A method according to claim 10, wherein R_A,1 =B*S_A,1 and R_B,1 =B*S_B,1.

12. A method according to claim 10, wherein said step of producing first output data at a rate R_A,1 bits per frame comprises a step of compressing said first isochronous input data to produce said first output data at said rate R_A,1.

13. A method according to claim 12, wherein said step of compressing said first isochronous input data to produce said first output data at a rate R_A,1 comprises a step of compressing said first isochronous input data by a first data compression technique, and wherein said step of compressing said first isochronous input data to produce said first output data at a rate R_B,1 comprises a step of compressing said first isochronous input data by a second data compression technique different from said first data compression technique.

14. A method according to claim 13, wherein said second data compression technique is more lossy than said first data compression technique.

15. A method according to claim 10, further comprising the steps of:

allocating S_C,1 time slots in each of said frames for transmission via said communications medium by said first active terminal unit when a number N_C of said terminal units are active, N_C >

N_B and S_C,1 <

S_B,1 ; and

said first terminal unit compressing said first isochronous input data to produce said first output data at a rate R_C,1 bits per frame while S_C,1 time slots per frame are allocated to said first active terminal unit, R_C,1 ≦

B*S_C,1 <

R_B,1,

wherein said step of compressing said first isochronous input data to produce said first output data at a rate R_B,1 comprises a step of compressing said first isochronous input data by a second data compression technique,

and wherein said step of compressing said first isochronous input data to produce said first output data at a rate R_C,1 comprises a step of compressing said first isochronous input data by a third data compression technique which is different from said second data compression technique.

16. A method according to claim 15, wherein both said second and third data compression techniques are lossy.

17. A method according to claim 15, wherein both said second and third data compression techniques are lossy, said third data compression technique being more lossy than said second data compression technique.

20. A method for operating a system having a plurality of terminal units each having an active and an inactive state with respect to a time multiplexed communications medium operating in temporally sequential frames during a subject time period, comprising the steps of:

allocating, when a number N_A of said terminal units are active, an amount of time T_A,i per unit time for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units; and

allocating, when a number N_B of said terminal units are active, N_B >

N_A, an amount of time T_B,i per unit time for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units,

wherein T_B,i <

T_A,i for at least a first one of said active terminal units,

wherein said step of allocating an amount of time T_A,i comprises a step of allocating a number S_A,i of time slots in each of said frames for transmission via said communications medium by each respective i'"'"'th one of said active terminal units,

wherein said step of allocating an amount of time T_B,i comprises a step of allocating a number S_B,i of time slots in each of said frames for transmission via said communications medium by each respective i'"'"'th one of said active terminal units,

and wherein said step of allocating S_B,i time slots in each of said frames comprises a step of allocating one time slot per two sub-frames for said second active terminal unit,

further comprising the steps of;

establishing a logical connection among a first set of at least two of the terminal units in said plurality of terminal units, said terminal units in said first set being active terminal units at least while said logical connection exists;

said control unit re-transmitting to a first one of the terminal units in said first set via said communications medium, first data received by said control unit during time slots allocated to a second one of the terminal units in said first set; and

said control unit re-transmitting to said second terminal unit in said first set via said communications medium, second data received by said control unit during time slots allocated to said first one of the terminal units in said first set.

21. A method according to claim 20, wherein said step of establishing a logical connection comprises the step of said control unit updating a connection table to indicate the terminal units which are subject to said logical connection, in response to a request via said communications medium from at least one of the terminal units in said first set to establish a logical connection.

22. A method according to claim 21, wherein said step of establishing a logical connection further comprises the step of broadcasting said connection table, as updated, via said communications medium.

23. A method according to claim 20, wherein each of said active terminal units has a respective address,

wherein said step of re-transmitting to a first one of said terminal units in said first set includes a step of transmitting said first data via said communications medium during outbound portions of said frames, with an identification of said first one of said terminal units in said first set,

and wherein said step of re-transmitting to a second one of the terminal units in said first set includes a step of transmitting said second data via said communications medium during outbound portions of said frames, with an identification of said second one of the terminal units in said first set.

24. A method according to claim 20, further comprising the steps of:

establishing a second logical connection among a second set of at least two of the terminal units in said plurality of terminal units, said terminal units in said second set being active terminal units at least while said second logical connection exists, said second set being distinct from said first set;

said control unit re-transmitting to a first one of the terminal units in said second set via said communications medium, third data received by said control unit during time slots allocated to a second one of the terminal units in said second set;

said control unit re-transmitting to said second one of the terminal units in said second set via said communications medium, fourth data received by said control unit during time slots allocated to said first one of the terminal units in said second set;

each of the terminal units in said second set receiving and discarding all of said first and second data re-transmitted by said control unit to terminal units in said first set; and

each of the terminal units in said first set receiving and discarding all of said third and fourth data re-transmitted by said control unit to terminal units in said second set.

26. A communications system for conducting communications via a wireless communications medium operating with temporally sequential frames, comprising:

a plurality of terminal units, each having an active and an inactive state and each active one of said terminal units receiving respective input data at a respective input data rate; and

a base unit which allocates for transmissions by each i'"'"'th one of said active terminal units a respective number S_A,i of incoming time slots in each of said frames when the number of said terminal units which are active is between 1 and a first threshold N_A, inclusive, and a number S_B,i of incoming time slots in each of said frames when the number of said terminal units which are active is between N_A +1 and a number N_B, inclusive, N_B >

N_A, all of said incoming time slots having equal duration and S_B,i being different from S_A,i for at least one of said active terminal units,

each given active one of said terminal units including;

a data compression mechanism which, when S_B,i incoming time slots per frame are allocated to the given terminal unit, compresses the input data received by the given terminal unit sufficiently to fit within S_B,i time slots per frame, and which, when S_A,i incoming time slots per frame are allocated to the given terminal unit, compresses the input data received by the given terminal unit sufficiently to fit within S_A,i time slots per frame but insufficiently to fit within S_B,i per frame, each of said data compression mechanisms having a respective data output; and

a transmitter coupled to receive the data output of the data compression mechanism in the given terminal unit and to transmit such data output via said communications medium during the incoming time slots allocated to the given terminal unit.

27. A system according to claim 26, further for conducting conversations among members of respective distinct sets of said terminal units, wherein each of said frames further has allocated therein at least one outgoing time segment for transmissions by said base unit,

wherein said base unit comprises retransmission apparatus which receives the data transmitted by each of said active terminal units and retransmits it via said communications medium in packets during the outgoing time segments, each of said packets being directed to at least a respective particular terminal unit and containing data that is dependent upon the data received by said retransmission apparatus during incoming time slots which were allocated to members of the set of terminal units that includes the particular terminal unit.

28. A system according to claim 27, wherein each frame includes a number of outgoing time slots in said outgoing segments,

wherein the data re-transmitted by said retransmission apparatus and directed to each j'"'"'th one of said active terminal units is re-transmitted within S_j outgoing time slots per frame, S_j being the number of incoming time slots then allocated for transmissions by the j'"'"'th terminal unit,

and wherein each given active one of at least a subset of said terminal units further includes:

a receiver coupled to receive the packets transmitted by said base unit, said receiver having an output and providing thereon only data from received packets which are addressed to at least the given terminal unit; and

a data decompression mechanism coupled to the output of the receiver and which decompresses the data provided by said receiver to the input data rate of the given terminal unit.

29. A system according to claim 28, wherein the data contained in each subject one of said packets is dependent only upon data received by said terminal unit during incoming time slots which are allocated to members of the set of terminal units that includes the terminal unit to which the subject packet is directed.

30. A system according to claim 29, wherein said data decompression mechanism has an output, and wherein each certain terminal unit in one of said sets further includes:

a voice input device providing the input data of the certain terminal unit; and

an audio output device coupled to output the output of the data decompression mechanism of said certain terminal unit.

31. A control unit for use with a plurality of terminal units each having an active and an inactive state with respect to a shared communications medium having a total capacity C for transmissions by said terminal units, said communications medium operating in temporally sequential frames during a subject time period, comprising:

means for allocating, when a number N_A of said terminal units are active, a portion C_A,i of said total capacity C for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units; and

means for allocating, when a number N_B of said terminal units are active, N_B >

N_A, a portion C_B,i of said total capacity C for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units,

wherein C_B,i <

C_A,i for at least a first one of said active terminal units,

wherein said means for allocating a portion C_A,i of said total capacity C comprises means for allocating a number S_A,i of time slots in each of said frames for transmission via said communications medium by each respective i'"'"'th one of said active terminal units,

wherein said means for allocating a portion C_B,i of said total capacity C comprises means for allocating a number S_B,i of time slots in each of said frames for transmission via said communications medium by each respective i'"'"'th one of said active terminal units,

wherein each of said frames is divided into a plurality of sub-frames, and wherein said means for allocating S_A,i time slots in each of said frames comprises means for allocating one time slot per sub-frame for a second one of said active terminal units,

and wherein said step of allocating S_B,i time slots in each of said frames comprises a step of allocating one time slot per two sub-frames for said second active terminal unit.

32. A control unit according to claim 31, wherein each of said means for allocating comprises the means in said control unit for transmitting, via said communications medium, an indication of the portion of said total capacity C allocated for transmissions via said communications medium by each of said active terminal units.

33. A control unit according to claim 31, wherein said total capacity C is measured in time, C defining a total amount of time T which is allocable for transmissions by said terminal units per unit time,

wherein each said portion C_A,i of said total capacity C defines a respective amount of time T_A,i of said total amount of time T,

and wherein each said portion C_B,i of said total capacity C defines a respective amount of time T_B,i of said total amount of time T,

T_B,i being less than T_A,i for at least said first active terminal unit.

34. A control unit according to claim 33, further comprising means for allocating, when a number N_C of said terminal units are active, an amount of time T_C,i per unit time for transmission via said communications medium by each respective i'"'"'th one of said active terminal units, N_C >

N_B,

wherein T_C,i <

T_B,i for at least one of said active terminal units.

35. A control unit for use with a plurality of terminal units each having an active and an inactive state with respect to a shared communications medium having a total capacity C for transmissions by said terminal units, said communications medium operating in temporally sequential frames during a subject time period, comprising:

means for allocating, when a number N_A of said terminal units are active, a portion C_A,i of said total capacity C for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units; and

means for allocating, when a number N_B of said terminal units are active, N_B >

N_A, a portion C_B,i of said total capacity C for transmissions via said communications medium by each respective i'"'"'th one of said active terminal units,

wherein C_B,i <

C_A,i for at least a first one of said active terminal units,

wherein said means for allocating a portion C_A,i of said total capacity C comprises means for allocating a number S_A,i of time slots in each of said frames for transmission via said communications medium by each respective i'"'"'th one of said active terminal units,

wherein said means for allocating a portion C_B,i of said total capacity C comprises means for allocating a number S_B,i of time slots in each of said frames for transmission via said communications medium by each respective i'"'"'th one of said active terminal units,

wherein an outbound portion in each of said frames is allocated for transmission via said communications medium by said control unit, wherein a logical connection exists among a first set of at least two of the terminal units in said plurality of terminal units, said terminal units in said first set being active terminal units at least while said logical connection exists,

said control unit further comprising;

means for re-transmitting to a first one of the terminal units in said first set via said communications medium, first data received by said control unit during time slots allocated to a second one of the terminal units in said first set; and

means for re-transmitting to said second terminal unit in said first set via said communications medium, second data received by said control unit during time slots allocated to said first one of the terminal units in said first set.

36. A control unit according to claim 35, further comprising a memory having stored therein a connection table including an indication of the terminal units which are subject to said logical connection.

37. A control unit according to claim 36, further comprising means for establishing said indication in said connection table, in response to a request via said communications medium from at least one of the terminal units in said first set to establish a logical connection.

38. A control unit according to claim 35, wherein each of said active terminal units has a respective address,

wherein said means for re-transmitting to a first one of said terminal units in said first set includes means for transmitting said first data via said communications medium during outbound portions of said frames, in conjunction with an identification of said first one of said terminal units in said first set,

and wherein said means for re-transmitting to a second one of the terminal units in said first set includes means for transmitting said second data via said communications medium during outbound portions of said frames, in conjunction with an identification of said second one of the terminal units in said first set.