Real-time CSMA method having the capability to adaptively vary cell sizes and a wireless network for implementing the same

• US 5,946,631 A
• Filed: 10/17/1996
• Issued: 08/31/1999
• Est. Priority Date: 10/17/1996
• Status: Expired due to Term

• Current Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Original Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Inventors: Melnik, George A.
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/733,306
• Time in Patent Office: 1,048 Days
• Field of Search: 455/68, 455/421, 455/450, 455/453, 455/454, 455/522, 455/525, 455/69, 370/445, 370/338
• US Class Current: 455/522
• CPC Class Codes: H04B 17/318 Received signal strength

Abstract

A method in which incoming RF signals to a given node of a wireless network are detected in real-time by using a comparison circuit for comparing a signal which is indicative of the strength of an incoming RF signal with a prescribed threshold level. The output of the comparison circuit is coupled to an input of the digital signal processor (e.g., microprocessor) of the node. The microprocessor is preferably programmed to check this input prior to attempting to transmit data, thus minimizing the chances of a collision occuring due to overlapping data transmitting and receiving operations. Preferably, the prescribed threshold level utilized in the comparison circuit of a given node can be selectively varied in order to thereby selectively vary the size of the cell in which the given node resides. In this connection, the neighborhood or cell sizes in which the individual nodes in the network reside are preferably adaptively varied in such a manner as to maximize the data throughput of the entire network. Also disclosed is an individual network node for a wireless network and a wireless network which have the capability of implementing the above-described method.

Claims

1. In a wireless, packet-hopping network, a method for increasing throughput, the network including at least one network control node and a plurality of transceiver nodes, none of the nodes having a transmission strength sufficient to reach the entire network, information being transmitted through the network by packet hopping between nodes, the method comprising,

I. in at least one individual network node from amongst the transceiver nodes:

a. producing a strength indication signal indicative of the signal strength of an incoming signal;

b. comparing the strength indication signal with a threshold compare signal to produce a comparison output signal; and

c. implementing a cell size adjustment for the individual network node based on the comparison output signal; and

II. maintaining multiple parallel communication pathways throughout the network based on the cell size adjustment.

2. The method as set forth in claim 1, wherein:

the individual network node includes an RF receiver; and

,

the strength indication signal comprises an RSSI signal produced by the RF receiver.

3. The method as set forth in claim 1, wherein:

the individual network node includes a digital signal processing device; and

,

the comparison output signal is applied to a first input of the digital signal processing device.

4. The method as set forth in claim 3, wherein the first input of the digital signal processing device comprises an interrupt pin.

5. The method as set forth in claim 4, wherein the comparison output signal is also applied to a second input of the digital signal processing device.

6. The method as set forth in claim 5, Wherein the second input of the digital signal processing device comprises an RF channel status sensing pin.

7. The method as set forth in claim 3, wherein the first input of the digital signal processing device comprises an RF channel status sensing pin.

8. The method as set forth in claim 4, wherein the digital signal processing device comprises a microprocessor.

9. The method as set forth in claim 6, wherein the digital signal processing device comprises a microprocessor.

10. The method as set forth in claim 1, further comprising the step of selectively varying the voltage level of the threshold compare signal in order to thereby selectively vary the size of a cell in which the individual network node resides.

11. The method as set forth in claim 10, wherein:

the individual network node includes a digital signal processor; and

,

the step of selectively varying is automatically performed by the digital signal processor in accordance with a software program stored in the digital signal processor.

12. The method as set forth in claim 10, wherein the step of selectively varying is performed in response to network commands issued by the network control node.

13. The method as set forth in claim 10, wherein the step of selectively varying is performed in such a manner as to maximize data throughput of the network.

14. The method of claim 1 further comprising the step of invoking a delay in response to a particular value of the comparison output signal.

15. The method of claim 14 wherein the delay is a random delay prescribed by a CSMA protocol.