Signalling method of detecting hidden incumbent system in cognitive radio environment and channel fractioning method used to enable the method

• US 20080014880A1
• Filed: 02/21/2007
• Published: 01/17/2008
• Est. Priority Date: 07/14/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: INHA Industry Partnership Institute, Samsung Electronics Co. Ltd.
• Inventors: Chung, Jae Hak, Yoo, Sang-Jo, Kim, Hyun Ju, Hyon, Tae-In, Kim, Jae Moung
• Granted Patent: US 7,852,821 B2
• Time in Patent Office: Days
• US Class Current: 455/161.1
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A signaling method between a cognitive radio (CR) base station and a CR terminal in a CR environment, and a channel division method used for the signaling method, includes: detecting a channel usage of an incumbent system, which communicates with a CR base station; sensing an outband channel to communicate with the CR base station; receiving an EOS, which is broadcasted from the CR base station via the outband channel according to a predetermined period; and transmitting a sensing report signal with respect to the channel to the CR base station.

Claims

1. A signaling method which is performed by a cognitive radio (CR) base station in a CR environment, the method comprising:

broadcasting an Explicit Outband Signal (EOS) via at least one outband channel according to a predetermined period;

receiving a sensing report signal with respect to an incumbent system, which utilizes a predetermined channel, from a CR terminal which makes a communication via the outbound channel; and

switching the outband channel of the CR terminal to an available outband channel.

2. The method of claim 1, wherein the predetermined period is determined according to a requisite detection time of the incumbent system.

3. The method of claim 1, wherein, in the CR environment, a frame is transmitted and/or received according to an Orthogonal Frequency Division Multiplexing Access (OFDMA) scheme, and

the EOS is transmitted to the CR terminal via a downlink of the frame, and the sensing report signal is transmitted to the CR base station via an uplink of the frame.

4. The method of claim 1, wherein the EOS and the sensing report signal are transmitted and/or received via an EOS frequency band of the outband channel during an outband broadcast signaling transmission time.

5. The method of claim 1, wherein the switching comprises:

stopping the broadcasting of the EOS via the outband channel; and

searching for the available outband channel.

6. The method of claim 1, further comprising:

transmitting an acknowledgement signal with respect to the sensing report signal to the CR terminal.

7. The method of claim 6, wherein, in the CR environment, a frame is transmitted and/or received according to an OFDMA scheme, and

the EOS and the acknowledgement signal are transmitted to the CR terminal via a downlink of the frame, and the sensing report signal is transmitted to the CR base station via an uplink of the frame.

8. The method of claim 7, wherein the acknowledgement signal is transmitted via a k number of frames, which are transmitted within the predetermined period, and k is included in a Superframe Check Header (SCH) of the frame.

9. The method of claim 6, wherein the acknowledgement signal further includes identification information of the CR terminal which transmitted the sensing report signal, and the CR terminal, which did not receive the acknowledgement signal, retransmits the sensing report signal to the CR base station.

10. A signaling method which is performed by a cognitive radio (CR) terminal in a CR environment, the method comprising:

detecting a channel usage of an incumbent system in a predetermined channel, which communicates with a CR base station;

sensing an outband channel to communicate with the CR base station;

receiving an explicit outband signal (EOS), which is broadcasted from the CR base station via the outband channel according to a predetermined period; and

transmitting a sensing report signal with respect to the channel to the CR base station.

11. The method of claim 10, wherein the sensing report signal includes information that the outband channel is unavailable.

12. The method of claim 11, wherein the sensing report signal includes information that the channel is being used by the incumbent, or includes channel information which is measured by the CR terminal.

13. The method of claim 10, wherein the predetermined period is determined according to a requisite detection time of the incumbent.

14. The method of claim 10, wherein, in the CR environment, a frame is transmitted/received according to an OFDMA scheme, and

the EOS is transmitted to the CR terminal via a downlink of the frame, and the sensing report signal is transmitted to the CR base station via an uplink of the frame.

15. The method of claim 10, further comprising:

receiving an acknowledgement signal with respect to the sensing report signal from the CR base station.

16. The method of claim 15, further comprising:

retransmitting the sensing report signal to the CR base station when the acknowledgement signal is not received,

wherein the acknowledgement signal further includes identification information of the CR terminal which transmitted the sensing report signal.

17. A signaling method which is performed between a cognitive radio (CR) base station and at least one CR terminal in a CR environment, the method comprising:

broadcasting an explicit outbound signal (EOS) from the CR base station to the at least one CR terminal via at least one outband channel;

detecting a channel occupation of another system with respect to the at least one outband channel;

determining whether the other system corresponds to an incumbent system; and

stopping the broadcasting of the EOS, searching for an available channel, and changing the outband channel into the located available channel when the other system corresponds to the incumbent system.

18. The method of claim 17, further comprising:

searching for the available channel, then stopping the broadcasting of the EOS via the channel when the other system does not correspond to the incumbent system.

19. The method of claim 17, wherein the broadcasting comprises:

selecting at least one time slot within a predetermined outband signaling period; and

broadcasting the EOS via at least two outband channels using at least two transmitters in the selected time slot.

20. The method of claim 17, wherein the broadcasting comprises:

selecting at least one time slot within a predetermined outband signaling period; and

sequentially broadcasting the EOS via at least two outband channels using a single transmitter in the selected time slot during an outband broadcast signaling transmission time.

21. A signaling method performed between a cognitive radio (CR) base station and at least one CR terminal in a CR environment, the method comprising:

broadcasting an explicit outband signal (EOS) from the CR base station to the at least one CR terminal via a first outband channel;

detecting whether a system is occupying the first outband channel;

determining whether the system occupying the first outband channel is an incumbent system; and

if the system occupying the first outband channel corresponds to the incumbent system, searching for a second outband channel, and if the second outbound channel is available, terminating the broadcasting of the EOS and switching from the first outband channel to the second outband channel.

22. The method of claim 21, wherein the determination of whether the system occupying the first outband channel is an incumbent system is performed via a channel sensing method in a physical layer.

23. The method of claim 21, wherein the channel sensing method includes energy detection method and a fine/feature sensing method.

24. The method of claim 23, wherein the energy detection method includes a received signal strength indicator (RSSI) measurement of a signal transmitted from the system and a multi-resolution spectrum sensing method.

25. The method of claim 23, wherein the fine/feature sensing method includes a fine energy-based detection method, a signal feature detection method and a cycostationary feature detection method.

26. The method of claim 21, wherein, in the CR environment, a frame is transmitted and/or received according to an Orthogonal Frequency Division Multiplexing Access (OFDMA) scheme, and

the EOS is transmitted to the CR terminal via a downlink of the frame, and the sensing report signal is transmitted to the CR base station via an uplink of the frame.

27. The method of claim 26, wherein the OFDMA frame includes a Superframe Control Header (SCH), a Frame Check Header (FCCH), a downlink map (DL-MAP), an uplink map (UL-MAP), a downlink burst (DL-Burst), and an uplink burst (UL-Burst).

28. The method of claim 21, wherein the CR base station receives a sensing report signal from the CR terminal and transmits the EOS only within an outband broadcast signaling transmission time using channel division and the CR base station utilizes a remaining frequency band for data transmission.

29. The method of claim 21, wherein when the CR base station broadcasts the EOS to the CR terminal, an acknowledgment signal that a sensing report signal is successfully received is included in the EOS.