Reduction of access time delay in frequency-hopping radio systems using a direct sequence mode

• US 6,345,066 B1
• Filed: 03/22/1999
• Issued: 02/05/2002
• Est. Priority Date: 05/19/1998
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Haartsen, Jacobus Cornelis
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Ha, Dac V.
• Application Number:
  US09/273,545
• Time in Patent Office: 1,051 Days
• Field of Search: 375/130, 375/131, 375/132, 375/133, 375/134, 375/137, 375/140, 375/141, 375/145, 375/149, 375/354, 370/320, 370/335, 370/342, 370/344, 370/343, 370/503
• US Class Current: 375/130
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 2001/71563 Acquisition
• CPC Class Codes: H04B 7/2621 using frequency division multiple access [FDMA] H04B7/2615 takes precedence

Abstract

In a radio system that employs frequency hopping (FH), access time delay is reduced, without compromising processing gain, by adding direct-sequence (DS) spreading to the system. This results in a hybrid FH/DS system, wherein the use of DS spreading permits a reduction in the number of hop frequencies used during start-up. Once synchronization is achieved, pure FH spreading, rather than the hybrid FH/DS spreading, along with a greater number of hop frequencies are used.

Claims

1. A radio system comprising:

means for employing a hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication during startup of a connection; and

means for employing a pure frequency hopping spread-spectrum transmission mode of communication during a connected mode of the connection.

2. The radio system of claim 1, wherein the means for employing the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication during startup of the connection utilizes a chip rate that is identical to a bit transmission rate used by the pure frequency hopping spread-spectrum transmission mode of communication.

3. The radio system of claim 1, wherein the means for employing the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication during startup of the connection includes means for transmitting a page message that comprises a fixed chip sequence that is unique to a radio unit being paged.

4. The radio system of claim 3, wherein a chip rate of the page message is identical to a bit rate used during the pure frequency hopping spread-spectrum transmission mode of communication.

5. The radio system of claim 1, wherein the means for employing the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication during startup of the connection includes means for transmitting a page message that comprises a fixed chip sequence that is common to all radio units in the radio system.

6. The radio system according claim 5, wherein a chip rate of the page message is identical to a bit rate used during the pure frequency hopping spread-spectrum transmission mode of communication.

7. The radio system of claim 1, further comprising a sliding correlator for despreading a page message that is transmitted during startup of the connection.

8. The radio system of claim 7, wherein the sliding correlator is implemented as a tapped delay line.

9. The radio system of claim 1, wherein a processing gain of the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication equals or exceeds 17 dB.

10. The radio system of claim 1, wherein a hop rate utilized by a paging unit operating in the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication is a multiple of a hop rate utilized by the pure frequency hopping spread-spectrum transmission mode of communication.

11. The radio system of claim 1, wherein a hop sequence for use by the pure frequency hopping spread-spectrum transmission mode of communication comprises at least 75 hop frequencies.

12. The radio system of claim 1, wherein a first hop sequence for use by the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication consists of fewer hop frequencies than are defined by a second hop sequence for use by the pure frequency hopping spread-spectrum transmission mode of communication.

13. The radio system of claim 12, wherein the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication has a processing gain that equals or just exceeds 17 dB.

14. An apparatus comprising:

means for employing a hybrid frequency hopping/direct sequence spread-spectrum mode of communication during a first mode of operation on a connection; and

means for employing a pure frequency hopping spread-spectrum mode of communication during a second mode of operation of the connection,

wherein a first hop sequence for use by the hybrid frequency hopping/direct sequence spread-spectrum mode of communication consists of fewer hop frequencies than are defined by a second hop sequence for use by the pure frequency hopping spread-spectrum mode of communication.

15. A method of operating a transceiver in a radio system, comprising the steps of:

employing a hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication during startup of a connection; and

employing a pure frequency hopping spread-spectrum transmission mode of communication during a connected mode of the connection.

16. The method of claim 15, wherein the step of employing the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication during startup of the connection comprises utilizing a chip rate that is identical to a bit transmission rate used by the pure frequency hopping spread-spectrum transmission mode of communication.

17. The method of claim 15, wherein the step of employing the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication during startup of the connection includes transmitting a page message that comprises a fixed chip sequence that is unique to a radio unit being paged.

18. The method of claim 17, wherein a chip rate of the page message is identical to a bit rate used during the pure frequency hopping spread-spectrum transmission mode of communication.

19. The method of claim 15, wherein the step of employing the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication during startup of the connection includes transmitting a page message that comprises a fixed chip sequence that is common to all radio units in the radio system.

20. The method of claim 19, wherein a chip rate of the page message is identical to a bit rate used during the pure frequency hopping spread-spectrum transmission mode of communication.

21. The method of claim 15, further comprising the step of using a sliding correlator to despread a page message that is transmitted during startup of the connection.

22. The method of claim 21, wherein the sliding correlator is implemented as a tapped delay line.

23. The method of claim 15, wherein a processing gain of the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication equals or exceeds 17 dB.

24. The method of claim 15, wherein:

the step of employing the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication during startup of the connection utilizes a first hop rate;

the step of employing the pure frequency hopping spread-spectrum transmission mode of communication during a connected mode of the connection uses a second hop rate; and

the first hop rate is a multiple of the second hop rate.

25. The method of claim 15, wherein the step of employing the pure frequency hopping spread-spectrum transmission mode of communication during a connected mode of the connection uses a hop sequence that comprises at least 75 hop frequencies.

26. The method of claim 15, wherein:

the step of employing the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication during startup of the connection utilizes a first hop sequence;

the step of employing the pure frequency hopping spread-spectrum transmission mode of communication during a connected mode of the connection uses a second hop sequence; and

the first hop sequence consists of fewer hop frequencies than are defined by the second hop sequence.

27. The method of claim 26, wherein the hybrid frequency hopping/direct sequence spread-spectrum transmission mode of communication has a processing gain that equals or just exceeds 17 dB.

28. A method of operating a transceiver in a radio system, comprising the steps of:

employing a hybrid frequency hopping/direct sequence spread-spectrum mode of communication during a first mode of operation on a connection; and

employing a pure frequency hopping spread-spectrum mode of communication during a second mode of operation of the connection,

wherein a first hop sequence for use by the hybrid frequency hopping/direct sequence spread-spectrum mode of communication consists of fewer hop frequencies than are defined by a second hop sequence for use by the pure frequency hopping spread-spectrum mode of communication.