CHANNEL PROBING SIGNAL FOR A BROADBAND COMMUNICATION SYSTEM

• US 20200313948A1
• Filed: 06/16/2020
• Published: 10/01/2020
• Est. Priority Date: 01/29/2004
• Status: Active Grant

• Current Assignee: Neo Wireless LLC (f/k/a CFIP NCF LLC) (SoftBank Group Corp.)
• Original Assignee: Neo Wireless LLC (f/k/a CFIP NCF LLC) (SoftBank Group Corp.)
• Inventors: Li, Xiaodong, Lo, Titus, Li, Kemin, Huang, Haiming
• Granted Patent: US 10,833,908 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/711 the interference being multi-path interference
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/03834 using pulse shaping
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0028 Variable division signaling therefor H04L5/0092

Abstract

In a broadband wireless communication system, a spread spectrum signal is intentionally overlapped with an OFDM signal, in a time domain, a frequency domain, or both. The OFDM signal, which inherently has a high spectral efficiency, is used for carrying broadband data or control information. The spread spectrum signal, which is designed to have a high spread gain for overcoming severe interference, is used for facilitating system functions such as initial random access, channel probing, or short messaging. Methods and techniques are devised to ensure that the mutual interference between the overlapped signals is minimized to have insignificant impact on either signal and that both signals are detectable with expected performance by a receiver.

Claims

1. A mobile station comprising:

a transmitter configured to;

transmit, to a base station, a first uplink signal within a frequency band, wherein the first uplink signal is an orthogonal frequency division multiplexing (OFDM) signal and utilizes a frame format comprising a plurality of timeslots, each timeslot comprising a plurality of OFDM symbols;

transmit, to the base station, an initial random access signal followed by a guard period in only a portion of the frequency band, wherein the initial random access signal includes a sequence associated with the base station and a time duration of the initial random access signal and the guard period is greater than a time duration of at least one of the plurality of OFDM symbols; and

a receiver configured to receive, from the base station, a response message.

2. The mobile station of claim 1, wherein:

the receiver is configured to determine if the response message identifies the sequence associated with the base station in the initial random access signal; and

on a condition that the response message identifies the sequence associated with the base station in the initial random access signal, the transmitter is configured to transmit a second uplink signal.

3. The mobile station of claim 2, wherein the response message includes power adjustment information and wherein the transmitter is configured to transmit the second uplink signal according to the power adjustment information.

4. The mobile station of claim 1, wherein the portion of the frequency band used for transmission of the initial random access signal does not include control channels.

5. The mobile station of claim 1, wherein the response message includes a mobile station identifier assigned to the mobile station.

6. The mobile station of claim 1, wherein the time duration of the initial random access signal and the guard period is greater than a time duration of at least two of the plurality of OFDM symbols.

7. The mobile station of claim 1, wherein the frequency band includes an outer portion and a center portion, wherein the portion of the frequency band for the initial random access signal is in the center portion and uplink control signals are sent in the outer portion.

8. The mobile station of claim 1, wherein the initial random access signal is a spread spectrum signal.

9. The mobile station of claim 1, wherein:

the receiver is further configured to receive broadcast information from the base station, the broadcast information indicating at least one sequence associated with the base station for use in producing the initial random access signal.

10. The mobile station of claim 1, wherein the transmitter includes an OFDM transmitter signal processing circuit comprising:

a serial to parallel converter, an inverse Fourier transform, and a cyclic prefix addition circuit; and

the OFDM transmitter signal processing circuit outputs the first uplink signal.

11. A method performed by a mobile station, the method comprising:

transmitting, to a base station, a first uplink signal within a frequency band, wherein the first uplink signal is an orthogonal frequency division multiplexing (OFDM) signal and utilizes a frame format comprising a plurality of timeslots, each timeslot comprising a plurality of OFDM symbols;

transmitting, to the base station, an initial random access signal followed by a guard period in only a portion of the frequency band, wherein the initial random access signal includes a sequence associated with the base station and a time duration of the initial random access signal and the guard period is greater than a time duration of at least one of the plurality of OFDM symbols; and

receiving, from the base station, a response message.

12. The method claim 11, further comprising:

determining if the response message identifies the sequence associated with the base station in the initial random access signal; and

on a condition that the response message identifies the sequence associated with the base station in the initial random access signal, transmitting a second uplink signal.

13. The method of claim 12, wherein the response message includes power adjustment information and wherein the second uplink signal is transmitted according to the power adjustment information.

14. The method of claim 11, wherein the portion of the frequency band used for transmission of the initial random access signal does not include control channels.

15. The method of claim 11, wherein the response message includes a mobile station identifier assigned to the mobile station.

16. The method of claim 11, wherein the time duration of the initial random access signal and the guard period is greater than a time duration of at least two of the plurality of OFDM symbols.

17. The method of claim 11, wherein the frequency band includes an outer portion and a center portion, wherein the portion of the frequency band for the initial random access signal is in the center portion and uplink control signals are sent in the outer portion.

18. The method of claim 11, wherein the initial random access signal is a spread spectrum signal.

19. The method of claim 11, further comprising:

receiving broadcast information from the base station, the broadcast information indicating at least one sequence associated with the base station for use in producing the initial random access signal.

20. The method of claim 11, wherein the first uplink signal is provided by an OFDM transmitter signal processing circuit comprising:

a serial to parallel converter, an inverse Fourier transform, and a cyclic prefix addition circuit.

21. A mobile station comprising:

a first type of transmitter signal processing circuit configured to;

generate a first uplink signal, wherein the first uplink signal is an orthogonal frequency division multiplexing (OFDM) signal and utilizes a frame format comprising a plurality of timeslots, each timeslot comprising a plurality of OFDM symbols;

modulate the first uplink signal onto a first set of OFDM subcarriers;

a second type of transmitter signal processing circuit configured to generate an initial random access signal followed by a guard period, wherein the initial random access signal includes a sequence associated with a base station and a time duration of the initial random access signal and the guard period is greater than a time duration of at least one of the plurality of OFDM symbols;

a circuit configured to provide at least the first uplink signal or the initial random access signal to output a digital signal;

a digital-to-analog (D/A) conversion circuit configured to convert the digital signal to an analog signal;

wherein the mobile station is configured to transmit, to the base station, the analog signal in a frequency band, wherein the initial random access signal occupies in a frequency domain only a portion of the frequency band;

wherein the mobile station is further configured to receive, from the base station, a second analog signal; and

wherein the mobile station further comprises;

an analog-to-digital (A/D) conversion circuit configured to convert the second analog signal to a second digital signal; and

a receiver circuit configured to receive, based on the second digital signal, a response message.

22. The mobile station of claim 21, wherein:

the receiver circuit is configured to determine if the response message identifies the sequence associated with the base station in the initial random access signal; and

on a condition that the response message identifies the sequence associated with the base station in the initial random access signal, the first type of transmitter signal processing circuit is configured to transmit a second uplink signal.

23. The mobile station of claim 22, wherein the response message includes power adjustment information and wherein the first type of transmitter signal processing circuit is configured to transmit the second uplink signal according to the power adjustment information.

24. The mobile station of claim 21, wherein the portion of the frequency band used for transmission of the initial random access signal does not include control channels.

25. The mobile station of claim 21, wherein the response message includes a mobile station identifier assigned to the mobile station.

26. The mobile station of claim 21, wherein time duration of the initial random access signal and the guard period is greater than a time duration of at least two of the plurality of OFDM symbols.

27. The mobile station of claim 21, wherein the frequency band includes an outer portion and a center portion, wherein the portion of the frequency band for the initial random access signal is in the center portion and uplink control signals are sent in the outer portion.

28. The mobile station of claim 21, wherein the initial random access signal is a spread spectrum signal.

29. The mobile station of claim 21, wherein:

the receiver circuit is further configured to receive broadcast information from the base station, the broadcast information indicating at least one sequence associated with the base station for use in producing the initial random access signal.

30. The mobile station of claim 21, wherein:

the first type of transmitter signal processing circuit is an OFDM transmitter signal processing circuit comprising;

a serial to parallel converter, an inverse Fourier transform, and a cyclic prefix addition circuit; and

the OFDM transmitter signal processing circuit outputs the first uplink signal.