Method for spectrum sensing in cognitive radio networks with open wireless architecture

• US 8,666,421 B2
• Filed: 08/25/2011
• Issued: 03/04/2014
• Est. Priority Date: 05/13/2011
• Status: Active Grant

• Current Assignee: Palo Alto Research, Inc.
• Original Assignee: Jenny Hu, Limei Xu
• Inventors: Xu, Limei, Hu, Jenny
• Primary Examiner(s): PATEL, MAHENDRA R
• Application Number:
  US13/217,743
• Publication Number:
  US 20120289236A1
• Time in Patent Office: 922 Days
• Field of Search: 455450-454, 455/574, 455/343.2, 370/338, 370/278, 370/319, 370/280, 370/281
• US Class Current: 455/446
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition

Abstract

This invention relates to a method for controlling location distribution of sensing nodes, selection of sensing nodes, control of sensing implementation and process of performing spectrum sensing in cognitive radio networks of open wireless architecture (OWA) systems. Specifically, the invention relates to an efficient and reliable method minimizing time overhead consumed during spectrum sensing with open wireless architecture (OWA).

Claims

1. An Open Wireless Architecture (OWA) spectrum sensing method for secondary user of spectrum in cognitive radio networks, said method comprising selection of sensing node, configuration for location of each said sensing node, sensing frame for control of sensing process, and division of sensing region, wherein configuration of said sensing node is based on node selection and node location in different divided small sensing areas, and implementation of said sensing process is based on both sensing scheduling and spectrum signal sensing, and

wherein priority for said selection of sensing node is divided into fourth levels, each denoted by two bits, f2 and f3 in said sensing frame, and for each said secondary user, active or idle condition is represented by letting f2 be 1 or 0 respectively, and delay-sensitive or non-delay-sensitive service is denoted by making f3 be 1 or 0 respectively, so that each said secondary user can be in one of four conditions, 00, 01, 10 and 11 that are first, second, third and fourth priority level respectively, wherein said selection of sensing node is completed based on joint consideration of current user condition (active or idle) and type of service (delay-sensitive or non-delay-sensitive) to select each said sensing node before sensing task is started.

2. The method as recited in claim 1, wherein said control of sensing process comprises decision on final sensing result for said secondary user and utilization condition of sensed frequency band of primary user, implemented in a decision center in base-station (BS) within a cell, comprising three factors of configuration process of sensing node, process of sensing implementation and condition of signal, denoted by f4, f5 and f6 respectively.

3. The method as recited in claim 2, wherein said decision center further manages control for location distribution of said sensing node and said selection of sensing node of sensing scheduling based on said sensing frame at medium access control layer and spectrum signal sensing at physical layer which is a cross-layer cooperation process.

4. The method as recited in claim 2, wherein said primary user refers to licensed user of spectrum, and said secondary user refers to unlicensed user of spectrum.

5. The method as recited in claim 1, wherein said sensing frame comprises region indication, said user condition, said type of service, said configuration process of sensing node, said process of sensing implementation and said condition of signal in sensed frequency band, wherein said region indication is represented by sector index when applied to wireless cellular networks, and said region indications are obtained by said BS by using dedicated channel.

6. The method as recited in claim 1, wherein said sensing process of each said sensing node is controlled by said decision center in said BS that organizes all said sensing nodes within said cell to implement synchronization process for sensing the same frequency band, as a result, increasing probability of obtaining correct sensing result of said sensing node collected by said decision center in said BS.

7. The method as recited in claim 1, wherein said spectrum sensing can be combined with traffic statistics determined by application layer of said secondary user system to form joint sensing scheme of physical layer for spectrum signal sensing, medium access control layer for sensing scheduling with said sensing frame and said application layer for user traffic control.

8. The method as recited in claim 3, wherein said cell is divided into three small areas called three sectors, and in each said sector, some said sensing nodes need to be placed in order to take advantage of radio signal space diversity for reliable fusion and decision of sensing results when said primary user network is a wireless cellular network, wherein said sector index of each user in said cell is indicated by using two bits, f0 and f1.

9. The method as recited in claim 8, wherein additional said sensing nodes are placed in most neighboring area based on the minimum distance rule when there is no user'"'"'s said sensing node in a said sector.

10. The method as recited in claim 8, wherein, when there is no user'"'"'s said sensing node in large region where it is hard to select said sensing node, joint sensing of multiple cells is used so that a final decision on sensing result is based on fusion of multiple said sensing results from multiple said decision centers located in different said cells.

11. The method as recited in claim 2, wherein said BS can be any wireless network equipment including gateway, switching system, router and other networking system connecting both backbone networks and wireless mobile terminals or devices.

12. The method as recited in claim 2, wherein said decision center is also a control center of spectrum sensing which can be located in said BS, a switching center, a network gateway, a network router, a virtual mobile server, a virtual networking system or a mobile cloud server.

13. The method as recited in claim 2, wherein said primary user networks and said secondary user networks can be wireless cellular networks, wireless local area networks (WLAN), wireless personal access networks (WPAN), broadband wireless access systems and networks (BWA), wireless metropolitan area networks (WMAN) and converged wireless networks of multiple different wireless standards.

14. The method as recited in claim 2, wherein said sensing process implemented in said decision center further comprises:

a) Estimation and prediction of traffic condition based on comparison between average queuing delay of users and average waiting time in a cell for users,

b) Configuration of said sensing nodes based on four parameters of said f0, said f1, said f2 and said f3 including said priority level and said sector index,

c) Implementation of said spectrum sensing, including starting said sensing process, reconfiguring said sensing nodes, implementing said spectrum sensing and completing said sensing process based on medium access control layer process and physical layer process, and

d) Fusion of sensing results and final decision on sensed spectrum.

15. The method as recited in claim 14, wherein said configuration of sensing node is started when said average waiting time in said cell in certain time slot is bigger than specified threshold of said average queuing delay for said sensing node.

16. The method as recited in claim 14, wherein said traffic condition in terms of said average queuing delay of said secondary users is estimated in said decision center by using time window with low pass property.

17. The method as recited in claim 16, wherein said time window of the shorter length is used to decrease time overhead in said spectrum sensing when each said sensing node adopts the same detection and sensing method, and said time window length should be increased in order to guarantee the reliability of said sensing process if different said sensing nodes use different detection and sensing methods, wherein said time window length is updated for the reliable synchronous said sensing process and the shorter said time window length is more efficient for the identification of said sensed spectrum.

18. An Open Wireless Architecture (OWA) spectrum sensing method for secondary user of spectrum in cognitive radio networks, said method comprising selection of sensing node, configuration for location of each said sensing node, sensing frame for control of sensing process, and division of sensing region, wherein configuration of said sensing node is based on node selection and node location in different divided small sensing areas, and implementation of said sensing process is based on both sensing scheduling and spectrum signal sensing, and

wherein said method further comprising a process as to which frequency band is sensed by which said sensing node that is a cooperative sensing mechanism by using multiple selected said sensing nodes, wherein each said secondary user of spectrum is selected as one of said sensing nodes depending on its current service condition (active or idle) and if one said secondary user is idle, then it may be selected as one said sensing node to fulfill local spectrum utilization sensing with a local sensing result collected by a decision center of said spectrum sensing, otherwise it is not selected to complete sensing task,

wherein priority for said selection of sensing node is divided into fourth levels, each denoted by two bits, f2 and f3 in said sensing frame for said control of sensing process, and for each said secondary user, active or idle condition is represented by letting f2 be 1 or 0 respectively, and delay-sensitive or non-delay-sensitive service is denoted by making f3 be 1 or 0 respectively, so that each said secondary user can be in one of four conditions, 00 01, 10 and 11 that are first, second, third and fourth priority level respectively, wherein said selection of sensing node is completed based on joint consideration of current user condition (active or idle) and type of service (delay-sensitive or non-delay-sensitive) to select each said sensing node before sensing task is started.