Flexible two-way telecommunication system

• US 6,407,993 B1
• Filed: 04/30/1998
• Issued: 06/18/2002
• Est. Priority Date: 05/08/1997
• Status: Expired due to Term

• Current Assignee: Uniloc 2017 LLC (SoftBank Group Corp.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Moulsley, Timothy J.
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US09/070,216
• Time in Patent Office: 1,510 Days
• Field of Search: 370/277, 370/280, 370/294, 370/311, 370/320, 370/321, 370/329, 370/331, 370/332, 370/333, 370/335, 370/337, 370/342, 370/347, 370/349, 370/389, 370/441, 370/442, 370/465, 370/466, 455/432, 455/436, 455/450, 455/451, 455/452, 455/509, 455/517, 455/522, 375/131
• US Class Current: 370/347
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0018 based on latency requirement
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0079 Formats for control data H04L1/16 takes precedence; training sequences H04L25/00 and H04L27/00
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A flexible two-way telecommunications system is disclosed having geographically distributed primary stations whose coverage areas define contiguous cells. Secondary stations are capable of roaming between and within the coverage areas of the primary stations. Downlink communications from the primary stations use TDMA transmission and uplink transmissions from the secondary stations use CDMA/TDMA transmissions. Data packets transmitted on the downlink are modulated to suit the quality of the link between the primary station and the addressed secondary station. A header applied to the downlink transmission includes information about the location of the respective data packets relative to a reference point and the modulation scheme applied to each data packet.

Claims

1. A method for transmitting and receiving signals between a primary station and a plurality of secondary stations in a single downlink frame, said method comprising the steps of:

a) receiving first signals at said primary station from said secondary stations on an uplink;

b) estimating the quality of each of said received uplink signals at said primary station;

c) individually selecting modulation and coding schemes at said primary station in accordance with said estimated signals received on said uplinks for each of said secondary stations;

d) modulating second signals according to selected modulation and coding schemes for each of said secondary stations; and

e) transmitting said selectively modulated and coded second signals to each of said secondary stations on a single downlink frame, said downlink frame including a frame structure having a header for said frame and a data burst for each modulated second signal for each secondary station, said header providing information enabling each secondary station to locate its respective data burst within the frame structure.

2. A method as claimed in claim 1, wherein said estimating step includes selecting said modulation and coding schemes on the basis of at least one of the following:

received signal strength indication;

bit rate;

bit error rate; and

end-to-end delay.

3. A method as claimed in claim 1, wherein said transmitting step includes downlink transmissions that comprise time frames, where each time frame includes a header having indicia indicating the transmission characteristics and timing of each data burst in the time frame.

4. A method as claimed in claim 1, wherein said transmitting step includes downlink transmissions that are TDMA.

5. A method as claimed in claim 1, wherein said receiving step includes uplink transmissions that are CDMA and/or TDMA.

6. A two-way telecommunication system including a primary station and at least one secondary station, each station capable of receiving and transmitting signals, said system comprising:

a) means at said primary station for receiving first signals one or more secondary stations on an uplink;

b) means for estimating the quality of each of said received first signals at said primary station;

c) means for individually selecting modulation and coding schemes at said primary station in accordance with said estimated first signals received on said uplink for each of said secondary stations;

d) means for modulating second signals according to selected modulation and coding schemes for each of said secondary stations; and

e) means at said primary station for transmitting said selectively modulated and coded second signals to each of said secondary stations on a single downlink frame, said downlink frame including a frame structure having a header for said frame and a data burst for each modulated second signal for each secondary station, said header providing information enabling each secondary station to locate its respective data burst within the frame structure.

7. A system as claimed in claim 6, characterized in that the primary station transmits downlink signals in accordance with a TDMA format comprising a succession of time frame structures, each including said frame header.

8. A system as claimed in claim 7, characterized in that the frame header includes indicia indicating the location of data bursts intended for one or more of the secondary stations.

9. A system as claimed in claim 8, characterized in that the frame header includes indicia indicating the format and timing of each data burst.

10. A system as claimed in claim 8, characterized in that training sequences are embedded in data bursts.

11. A system as claimed in claim 7, characterized in that at least one secondary station effects power saving by adopting a sleep mode whenever the secondary station determined that data bursts are directed to other secondary stations.

12. A system as claimed in claim 7, characterized in that the time frames are of a substantially fixed duration.

13. A system as claimed in claim 6, characterized in that the modulating means applies a high order modulation scheme to signals to be transmitted to secondary stations relatively close to the primary station and low bit rate orthogonal codes when transmitting signals to relatively distant secondary stations.

14. A system as claimed in claim 6, characterized in that traffic data is transmitted on the downlink with a modulation scheme and power level determined to ensure reliable receipt by a secondary station.

15. A system as claimed in claim 6, characterized in that uplink signals are transmitted as CDMA signals.

16. A system as claimed in claim 6, characterized in that uplink signals are transmitted in accordance with a TDMA format.

17. A system as claimed in claim 16, characterized in that TDMA uplink signals comprise at least two data bursts and in that a guard space is provided between adjacent data bursts.

18. A system as claimed in claim 16, characterized in that TDMA uplink signals comprise at least two data bursts, and that each data burst comprises at least one training sequence.

19. A system as claimed in claim 16, characterized in that TDMA uplink signals comprise data packets, and in that the bit rates of at least two of the data packets are different.

20. A system as claimed in claim 6, characterized in that timing for uplink signals is derived from the downlink signals.

21. A system as claimed in claim 6, characterized in that the system is a cellular system comprising a plurality of cells, each cell having a primary station definition a respective coverage area.

22. A system as claimed in claim 21, characterized in that primary stations have means for handing over a secondary station participating in a call from one cell to another cell.