Polling system for a duplex asymmetrical communications link

• US 6,721,285 B1
• Filed: 03/22/2000
• Issued: 04/13/2004
• Est. Priority Date: 03/30/1999
• Status: Expired due to Fees

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Carro, Fernando Incertis
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Boakye, Alexander O.
• Application Number:
  US09/532,224
• Time in Patent Office: 1,483 Days
• Field of Search: 370/449, 370/346, 370/277, 370/242, 370/458, 370/464, 370/465, 370/447, 370/450, 370/457, 455/463, 455/464, 455/465, 455/507, 455/508, 455/509, 710/109
• US Class Current: 370/277
• CPC Class Codes: H04W 74/06 using polling

Abstract

In a duplex communications system a master station transmits to and receives from a multiplicity of remote terminals over a shared broadcast communications channel. A polling method and system is disclosed which takes advantage of the asymmetrical reliability of the channel preferably broadcasting from the master station thus, forwarding polling commands carrying a status towards the remote terminals due to deliver responses including only the changes in order to use much more efficiently the channel. Also, the scheme allows to carry out most of the error recovery process in each remote terminal thus completely freeing the in master for its chief task, i.e., the management of the network of remote terminals.

Claims

1. In a duplex communications system comprising a master station which controls access by a multiplicity of remote terminals to a broadcasting channel, said channel being for transmitting and receiving signals to and from said controlled remote terminals, a method of polling from said master station all said remote terminals, comprising the steps of:

broadcasting from a master station a polling command destined to a particular remote terminal, the polling command including a unique identifier and a status of the particular remote terminal which is stored in the master station;

receiving in all the remote terminals the polling command which is decoded so that only one of the remote terminals, recognizing its identifier, performs a self selection;

comparing, in the self selecting remote terminal, the status read in the polling command versus the actual current status of the self selecting remote terminal;

if no difference is observed between the current status of the terminal and the status in the polling command, forwarding to the master station, from the self selecting remote terminal, a response to the polling command including a report that no difference is observed between the current status of the terminal and said status of said polling command;

if a difference is observed between the current status of the terminal and the status in the polling command, forwarding to the master station, from the self selecting remote terminal, a response to the polling command including a report of the differences observed between the current status of the terminal and the status of the polling command; and

,

updating in the master station the stored status of the answering terminal with the status corresponding to the reporting received in the response from the terminal.

2. The method of claim 1 further comprising the steps of continuously repeating the steps of claim 1 for all the remote terminals controlled by the master station while it is up and operating.

3. The method of claim 2 wherein each broadcasting step includes a step of selecting, as the status in the polling command, a subset of a whole status of the remote terminal stored in the master station, the subset being self-sufficient to control the particular remote terminal, said method further comprising the step of adapting selecting of subset according to the context.

4. The method of claim 1 wherein the step of response forwarding, if a difference is observed between the current status of the terminal and the status in the polling command, comprises the step of including in the response to the polling command sent from the terminal, any outstanding remote terminal generated change which affects the status.

8. The method of claim 1 wherein the steps of broadcasting the status and forwarding a response comprise the step of respectively preparing as the status and the response, a list of variables and associated variable attached checkfields respectively stored in the master station and in the remote terminal along with the variable values which are not transmitted and only stored in the remote terminal, the variable attached checkfields being used as signatures of the variables.

9. The method of claim 8 wherein the step of preparing the response first comprises a step of applying a priority order in the list of variables and their associated checkfields.

5. In a duplex communications system comprising a master station which controls access by a multiplicity of remote terminals to a broadcasting channel, said channel being for transmitting and receiving signals to and from said controlled remote terminals, a method of polling from said master station all said remote terminals, comprising the steps of:

broadcasting from a master station a polling command destined to a particular remote terminal, the polling command including a unique identifier and a status of the particular remote terminal which is stored in the master station;

receiving in all the remote terminals the polling command which is decoded so that only one of the remote terminals, recognizing its identifier, performs a self selection;

comparing, in the self selecting remote terminal, the status read in the polling command versus the actual current status of the self selecting remote terminal;

if no difference is observed between the current status of the terminal and the status in the polling command, forwarding to the master station, from the self selecting remote terminal, a response to the polling command including a report that no difference is observed between the current status of the terminal and said the status of said polling command;

if a difference is observed between the current status of the terminal and the status in the polling command, forwarding to the master station, from the self selecting remote terminal, a response to the polling command including a report of the differences observed between the current status of the terminal and the status of the polling command; and

,

updating in the master station the stored status of the answering terminal with the status corresponding to the reporting received in the response from the terminal, wherein the steps of broadcasting the status and forwarding a response comprise the step of preparing respectively as the status and the response, a list of variables and associated variable values respectively stored in the master station and in the remote terminal.

6. The method of claim 5 wherein the steps of preparing the status and the response further comprises a step of adding a global check field.

7. The method of claim 5 wherein the step of preparing the status and the response further comprises a step of adding to each variable and variable value a variable attached checkfield also respectively stored in the master station and in the remote terminal, the variable attached checkfields being used as signatures of the variables.

10. The method of claim 5 wherein the step of preparing the response first comprises a step of applying a priority order in the list of variables and their associated values.

11. A wireless terminal connected to a wireless network comprising:

a receiver for receiving downlink information from the master station;

a storage unit storing the current status of the terminal;

a processor analyzing a polling command received from a master station including one wireless terminal identification and its corresponding status and, if recognizing its terminal identification, comparing the status read in the polling command with the current status read in its storage;

a transmitter for transmitting uplink information to the master station in the form of a response to the polling command and including a reporting that no difference is observed between the current status of the terminal and said status of said polling command if it is the case or a reporting of the differences which are observed between the current status of the terminal and said status of said polling command.

12. A duplex communications system for communicating over a wireless network, said system comprising:

at least one master station including;

a transmitter for transmitting downlink information to the wireless network;

a storage unit, storing a table comprising wireless terminal identification and its status;

a processor computing a polling command which is then broadcasted on the wireless network and including one wireless terminal identification and its corresponding status;

a receiver receiving uplink information from the wireless network and particularly responses from the polled wireless terminals which are then processed by the processor and used to update the status of that polled terminals in the storage unit;

at least one wireless terminal including

a receiver for receiving downlink information from the master station;

a storage unit storing the current status of the terminal;

a processor analyzing the polling command received from the master station and, if recognizing its terminal identification, comparing the status read in the polling command with the current status read in its storage unit;

a transmitter for transmitting uplink information to the master station in the form of a response to the polling command and including a reporting that no difference is observed between the current status of the terminal and said status of said polling command if it is the case or a reporting of the differences which are observed between the current status of the terminal and said status of said polling command.