Radio network and method of establishing time synchronization among a plurality of buses

• US 6,502,155 B1
• Filed: 11/26/1999
• Issued: 12/31/2002
• Est. Priority Date: 11/30/1998
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kondo, Keitaro, Ueno, Masatoshi
• Primary Examiner(s): Ray, Gopal C.
• Application Number:
  US09/449,977
• Time in Patent Office: 1,131 Days
• Field of Search: 710/105, 710/305, 709/400, 709/248, 709/253, 370/464, 370/400, 455/403, 707/104.1, 713/500
• US Class Current: 710/305
• CPC Class Codes: G06F 1/14 Time supervision arrangements, e.g. real time clock
• CPC Class Codes: H04J 3/0655 using timestamps
• CPC Class Codes: H04L 12/40052 High-speed IEEE 1394 serial bus bus transfer protocol on a daisy chain bus using an embedded synchronisation G06F13/426
• CPC Class Codes: H04L 12/40058 Isochronous transmission

Abstract

WN nodes (2 to 5) set the number of clocks in low-order 12 bits of cycle time data from cycle masters (20-50) to a bus counter (102A) and an internal counter (102B). When a control block is transmitted to the WN nodes (3 to 5), the WN node (2) stores a counted value of the counter (102B) in a cycle sync area. The WN nodes (3 to 5) which receive the control block extract the counted value from the cycle sync area, generate control information for correcting a difference so as to maintain an initial value by comparing the extracted counted value and the counted value of the above-mentioned counter (102A), and transmits such control information to the cycle masters (30 to 50). Thus, the number of clocks in the low-order 12 bits of the cycle time data in the cycle masters (30 to 50) is corrected, and a time synchronization among respective buses is established. Therefore, a time synchronization among a plurality of buses may be established satisfactorily.

Claims

1. A radio network comprising a plurality of buses each having data transfer rate time information and being mutually connected over radio waves, said radio network comprising:

means for extracting the time information of one bus of said plurality of buses;

means for adjusting a time of other buses of said plurality of buses by using said extracted time information of said one bus; and

a radio communication unit for effecting radio communication among said plurality of buses, wherein said radio communication unit comprises one control node and more than one controlled nodes controlled by said control node and said control node is connected to said one bus and one of said controlled nodes is connected to one of said other buses.

2. The radio network as claimed in claim 1, wherein said plurality of buses have connected thereto a time management node for managing a time thereof, said control node includes time information transmission means for transmitting time information supplied thereto from the time management node on the bus connected thereto and to said one controlled node, and said controlled node includes time information reception means for receiving said time information transmitted from said control node, control information generation means for generating control information for said time adjustment by using said time information and time information from the time management node on the bus connected thereto, and control information transmission means for transmitting said control information to the time management node on the bus connected thereto.

3. The radio network as claimed in claim 2, wherein said time information is data indicative of a number of clock pulses, said control node includes a first counter for counting pulses in a clock signal in an ascending order, means for setting a counted value of said counter to become equal to the number of clock pulses determined by said data indicative of the number of clock pulses from the time management node on the bus connected thereto, and means for transmitting the counted value of said counter to said controlled node at a predetermined cycle, and said controlled node includes a second counter for counting pulses in a clock signal in an ascending order, means for setting the counted value of said counter to become equal to the number of clock pulses determined by said data indicative of the number of clock pulses from the time management node on the bus connected thereto, means for generating control information for said time adjustment by comparing the counted value of said first counter transmitted from said control node with the counted value of said second counter, and means for transmitting said control information to the time management node on the bus connected thereto.

4. A method of establishing a time synchronization among a plurality of buses in a radio network in which a control node is connected to one bus of said plurality of buses and a controlled node is connected to an other bus of said plurality of buses and radio communication is effected among said plurality of buses by said control node and said controlled node, comprising:

a step in which said control node transmits to said controlled mode time information extracted from a time management node on the bus connected to said control node; and

a step in which said controlled node generates control information using said time information transmitted from said control node for adjusting a time management node on a bus of said plurality of buses connected to said controlled node, whereby the time information at said control node and the time information at said controlled node are the same.

5. A method of establishing a time synchronization among a plurality of buses in a radio network in which a control node is connected to one bus of said plurality of buses and a controlled node is connected to an other bus of said plurality of buses and a radio communication is effected among said plurality of buses by said control node and said controlled node, comprising:

a step in which said control node transmits to said controlled node time information extracted from a time management node on said one bus of said plurality of buses connected to said control node;

a step in which a second controlled node connected to a second bus other than said one bus generates control information for a time adjustment by using time information transmitted from said control node and time information from a time management node on a bus of said plurality of buses connected thereto;

a step in which said controlled node connected to said one bus generates control information for a time adjustment by using said time information transmitted from said control node and time information from a time management node on a bus connected thereto and transmits said control information to said control node; and

a step in which said control node receives control information transmitted from said controlled node connected to said second bus, updates time information thereof by using said control information, generates control information for time adjustment by using said time information thereof and time information from a time management node on said one bus connected thereto, and transmits said control information thus generated to a time management node on the bus connected thereto, whereby the time information at said control node, at said controlled node, and at said second controlled node are the same.

6. A wireless network comprising:

a plurality of wireless network nodes, each having a data bus for data transfer based on respective bus timing information, wherein one of said plurality of wireless network nodes is designated a root node for providing control and remaining ones of said plurality of wireless network nodes are designated leaf nodes for being controlled,

said root node including a cycle master unit for extracting the timing information of the data bus connected to the root node, a root control unit, first and second counters for counting pulses based on the timing information from the cycle master unit, and a wireless transmit and receive unit,

said remaining ones of said plurality of wireless network nodes each including a cycle master unit for extracting the timing information from a respective data bus connected to the leaf node, a leaf control unit, a counter for counting pulses based on the timing information from the respective cycle master unit, and a wireless transmit and receive unit, wherein the count of the second counter of the root node is transmitted to each leaf node and each respective counter is controlled by the respective leaf control unit to the same count as said second counter, so that each data bus is synchronized with the data bus in the root node.