Method and apparatus for synchronizing radio ports in a commnuication system

• US 5,530,704 A
• Filed: 02/16/1995
• Issued: 06/25/1996
• Est. Priority Date: 02/16/1995
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Gibbons, David B., Maxwell, Robert L., Kilp, David P.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): BLUM, RUSSELL
• Application Number:
  US08/390,206
• Time in Patent Office: 495 Days
• Field of Search: 370/94.2, 370/100.1, 370/101, 370/105.1, 370/105, 370/4, 370/106, 370/108, 370/110.1, 370/95.3, 375/356, 455/33.1, 455/33.2, 455/51.1, 379/58-60, 379/63, 340/825.2, 340/825.21
• US Class Current: 370/510
• CPC Class Codes: H04J 3/0602 Systems characterised by the synchronising information used
• CPC Class Codes: H04J 3/0685 Clock or time synchronisation in a node; Intranode synchronisation

Abstract

A communication system (100) provides simultaneous synchronization between a network controller (106) and numerous radio ports (102) using a single signaling channel. The network controller (106) includes a multiframe synchronization generator (208) which generates a multiframe synchronization packet (302) in response to a series of counters (212) and a timing reference (202). Each radio port (102) includes a multiframe synchronization detector (410) which verifies that the multiframe synchronization packet (302) is error free.

Claims

1. A method of synchronizing a radio port to a network controller within a communication system, comprising the steps of:

establishing a timing reference at the network controller;

generating a multiframe number based on the timing reference;

generating a check byte in response to the multiframe number;

transmitting the multiframe number and check byte over a predetermined channel to the radio port;

receiving the multiframe number and check byte at the radio port;

providing the multiframe number to a state machine within the radio port;

validating the check byte to determine if the received multiframe number is error free; and

synchronizing the radio port to the network controller when the received multiframe number is error free.

2. A communication system, comprising:

a network controller for transmitting a multiframe synchronization event over a single communication channel;

a radio port for receiving the multiframe synchronization event, said radio port including means of determining if the multiframe synchronization event is error free; and

said radio port synchronizing to the network controller when the multiframe synchronization event is error free.

3. A communication system as described in claim 2, wherein the communication system is a digital European cordless telephone (DECT) system.

4. A method of synchronizing a radio port to a network controller in a communication system, comprising the steps of:

at the network controller;

establishing a timing reference;

determining a multiframe number, check byte, and synchronization event based on the timing reference;

generating digital signaling information including the multiframe number, check byte, and synchronization event;

transferring the digital signaling information to the radio port using a single communication channel; and

at the radio port;

receiving the digital signaling information;

determining if the digital signaling information is error free based on the check byte; and

synchronizing to the network controller when the digital signaling information is error free.

5. A method as described in claim 4, wherein a cyclic redundancy check (CRC) calculation is done to determine if the signaling information is error free.

6. A method as described in claim 4, wherein the step of receiving includes the step of using a state machine to receive the digital signaling information transmitted by the network controller;

and

the step of synchronizing includes the step of controlling the synchronization of the radio port to the network controller using the state machine.

7. A method as described in claim 4, wherein the step of receiving includes the step of using a universal asynchronous receiver/transmitter to receive the digital signaling information transmitted by the network controller;

and

the step of synchronizing includes the step of controlling the synchronization of the radio port to the network controller using the universal asynchronous receiver/transmitter.

8. A method of providing synchronization between a radio port and a network controller, comprising the steps of:

providing a synchronization packet over a predetermined time frame, including;

providing a multiframe number within the synchronization packet;

performing a predetermined cyclic redundancy check calculation on the multiframe number;

generating a cyclic redundancy check result; and

appending the multiframe number with the cyclic redundancy check result within the synchronization packet;

transmitting the synchronization packet over a predetermined communication channel;

detecting the synchronization packet at the radio port; and

synchronizing the radio port to the network controller in response to the synchronization packet.

9. A method of providing synchronization between a radio port and a network controller as described in claim 8, wherein the step of synchronizing includes the steps of:

disassembling the detected synchronization packet;

performing a second cyclic redundancy check calculation on the multiframe number; and

determining if the synchronization packet is error free based on the second cyclic redundancy check calculation.

10. A method of synchronizing a plurality of radio ports to a network controller in a communication system operating with a predetermined communication protocol, comprising the steps of:

generating a time reference related to the communication protocol;

generating a multiframe number based on the time reference;

performing a predetermined cyclic redundancy check calculation on the multiframe number to produce a check byte; and

broadcasting the multiframe number and the check byte to the plurality of radio ports simultaneously.

11. A method of synchronizing a plurality of radio ports to a network controller as described in claim 10, wherein the step of broadcasting includes the step of using a single predetermined communication channel to broadcast the multiframe number from the network controller to the plurality of radio ports.

12. A method of synchronizing a plurality of radio ports to a network controller as described in claim 10, further comprising the steps of:

providing a chain of counters within the network controller;

sourcing the chain of counters with the time reference; and

generating the multiframe number from the chain of counters in accordance with the predetermined communication protocol.

13. A method of synchronizing a plurality of radio ports to a network controller as described in claim 12, wherein the step of generating a multiframe number includes the steps of:

incrementing a pulse code modulated (PCM) frame count after a predetermined amount of time has elapsed based on the time reference;

comparing the PCM frame count to a predetermined PCM limit;

incrementing a second frame count when the PCM frame count reaches its predetermined PCM limit;

comparing the second frame count to a predetermined frame limit;

incrementing a multiframe count when the second frame count reaches its predetermined frame limit;

comparing the multiframe count to a predetermined multiframe limit; and

initiating a multiframe event when the multiframe count reaches its predetermined multiframe limit.

14. A method of synchronizing a plurality of radio ports to a network controller as described in claim 13, wherein the step of initiating a multiframe event includes the steps of:

generating a synchronization word;

appending the result of the performed CRC calculation onto the multiframe number; and

transmitting the synchronization word, the multiframe number, and the appended CRC result onto the single predetermined communication channel as a synchronization packet to the plurality of radio ports.

15. A method of synchronizing a plurality of radio ports to a network controller as described in claim 14, further comprising the steps of:

receiving the simultaneous broadcast at the radio ports;

disassembling the synchronization packet;

performing a predetermined CRC calculation on the synchronization packet;

validating the performed CRC calculation; and

determining if the synchronization packet is error free based on the step of validating the performed CRC calculation.

16. A method of synchronizing a plurality of radio ports to a network controller as described in claim 15, further comprising the steps of:

detecting the synchronization word at the plurality of radio ports;

starting a delay timer in response to the synchronization word;

determining when the delay timer expires; and

loading a multiframe counter with the multiframe number and resetting a series of bit, slot, and frame counters to zero when the delay timer expires and the synchronization packet is error free.

17. A communication system, comprising:

a network controller for transmitting a synchronization packet, said network controller including;

a reference timer;

a multiframe synchronization generator comprising;

a series of counters clocked by the reference timer and generating a multiframe number, said multiframe number being incremented in response to the series of counters;

a network controller state machine monitoring the series of counters and generating a synchronization word when the multiframe number is incremented;

a network controller cyclic redundancy checker for generating a check byte in response to the multiframe number;

said network controller state machine transmitting the synchronization word, multiframe number, and check byte as the synchronization packet; and

a radio port for receiving the synchronization packet, said radio port including;

a multiframe synchronization detector including;

a packet disassembler for reformatting the synchronization packet;

a synchronization word detector for detecting the synchronization word;

a radio port cyclic redundancy checker generating a check byte based on the received synchronization packet, said check byte determining if the receive synchronization packet is error free;

a radio port state machine for monitoring the status of the radio port cyclic redundancy checker; and

a series of counters responsive to the radio port state machine, a portion of said counters being updated with the multiframe number when the synchronization packet is error free while the remainder of said series of counters are reset; and

said network controller and said radio port being synchronized when the series of counters are updated with the multiframe number and the remainder of the series of counters are reset to zero.

18. A communication system as described in claim 17, wherein the radio port further comprises:

a programmable delay portion responsive to the radio port state machine and providing a predetermined delay time when the synchronization packet is error free, said series of counters being updated when the predetermined delay time has expired.

19. A communication system, comprising:

a network controller for transmitting a synchronization event including a synchronization packet and break character, said network controller including;

a reference timer;

a multiframe synchronization generator comprising;

a series of counters clocked by the reference timer and generating a multiframe number, said multiframe number being incremented in response to the series of counters;

a state machine monitoring the series of counters and generating the break character and a flag when the multiframe number is incremented;

a cyclic redundancy checker for generating a check byte in response to the multiframe number;

said state machine transmitting the flag, multiframe number, and check byte as the synchronization packet and also transmitting the break character; and

a radio port for receiving the synchronization event, said radio port including a universal asynchronous receiver and transmitter (UART) for sampling the synchronization packet using a universal asynchronous receiver and transmitter protocol; and

said universal asynchronous receiver and transmitter generating a synchronization pulse in response to the break character; and

said state machine of the network controller providing signaling substantially similar to the universal asynchronous receiver and transmitter protocol.