Surveillance system and network system

• US 6,501,377 B2
• Filed: 09/06/2001
• Issued: 12/31/2002
• Est. Priority Date: 08/31/1998
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Koizumi, Minoru, Sasaki, Toshiichiro, Ebata, Tomoichi, Adachi, Yoshiaki, Kitahara, Chiho
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US09/946,525
• Publication Number:
  US 20020067254A1
• Time in Patent Office: 481 Days
• Field of Search: 340/506, 340/505, 340/572.1, 340/3.1, 370/235, 370/253, 455/518, 455/519, 455/522, 455/524, 348/143, 348/9, 348/17, 348/21
• US Class Current: 340/506
• CPC Class Codes: G08B 13/19656 Network used to communicate with a camera, e.g. WAN, LAN, Internet
• CPC Class Codes: G08B 13/19693 using multiple video sources viewed on a single or compound screen
• CPC Class Codes: G08B 13/19697 Arrangements wherein non-video detectors generate an alarm themselves
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources

Abstract

In order to allow efficient use of bandwidth in communication paths in a surveillance system, the surveillance system has an operation unit which assigns fixed bandwidths to each of the communications taking place between camera nodes, which transfer image data at a uniform rate, and monitor nodes. A fixed bandwidth is assigned to, all communications taking place between the operation unit and sensor nodes, which generate alarm information at a non-uniform rate. If there is an increase in network traffic, bandwidth allocations, for communication between the camera nodes and the monitor nodes are reassigned so that bandwidth for these communications is reduced. The camera nodes use the bandwidth assigned to the camera nodes to transfer image data. The sensor nodes transfer alarm information using any bandwidth.

Claims

1. A method of controlling quality of communication among a plurality of client nodes and a control node over a network, said communication including a first type of communication and a second type of communication, said method comprising the steps of:

monitoring a state of said network caused by said first type of communication;

assessing a quality of communication over said network at said control node based on said state;

issuing an instruction based on the assessment from said control node for enabling said second type of communication with a predetermined quality; and

controlling said first type of communication under said instruction.

2. A method of controlling quality of communication according to claim 1, wherein said first type of communication is performed between at least two of said client nodes, and

wherein said step of controlling is performed by a client node that received said instruction.

3. A method of controlling quality of communication according to claim 2, wherein said monitoring step comprises the steps of:

reporting said state for assessment at said client node to said control node; and

receiving the report about said state from said client node at said control node.

4. A method of controlling quality of communication according to claim 2, wherein said step of reporting said state comprises the step of:

measuring data delay of said first type of communication.

5. A method of controlling quality of communication according to claim 2, wherein said step of controlling said first type of communication comprises the step of:

controlling bandwidth usage by said client node for said first type of communication.

6. A method of controlling quality of communication according to claim 5, wherein said instruction is indicative of reducing said bandwidth usage of said first type of communication to a predetermined bandwidth, and

wherein said step of controlling bandwidth usage at said client node comprises the step of:

reducing bandwidth usage of said first type of communication according to said instruction.

7. A method of controlling quality of communication according to claim 5, wherein said instruction is indicative of increasing said bandwidth usage of said first type of communication to a predetermined bandwidth, and

wherein said step of controlling bandwidth usage at said client node comprises the step of:

increasing bandwidth usage of said first type of communication according to said instruction.

8. A method of controlling quality of communication according to claim 2, wherein said control node is one of said client nodes concurrently, and

wherein said step of assessing is executed based on said state being monitored at said control node.

9. A method of controlling quality of communication according to claim 2, wherein said first type of communication transfers data uniformly over time and said second type of communication transfers data non-uniformly over time.

10. A method of controlling quality of communication according to claim 2, wherein said step of issuing said instruction comprises the step of:

broadcasting said instruction from said control node over said network.

11. A method of controlling quality of communication according to claim 10, wherein said communication is performed under CSMA/CD protocol.