Hybrid multiple access protocol for wireless frequency hopping microcells with adaptive backhaul and heartbeat

• US 5,818,828 A
• Filed: 10/04/1996
• Issued: 10/06/1998
• Est. Priority Date: 10/04/1996
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Metricom, Inc.
• Inventors: Bettendorff, John, Xu, Milton Y., Packer, Robert Lawrence
• Primary Examiner(s): TON, DANG T
• Application Number:
  US08/726,463
• Time in Patent Office: 732 Days
• Field of Search: 370/365, 370/366, 370/346, 370/347, 370/348, 370/350, 370/337, 370/321, 370/314, 370/442, 370/443, 370/444, 370/445, 370/447, 370/448, 370/449, 370/455, 370/458, 370/461, 370/462, 340/825.5, 340/825.51, 340/825.52, 340/825.08, 375/356
• US Class Current: 370/346
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/52 based on load
• CPC Class Codes: H04W 74/02 Hybrid access
• CPC Class Codes: H04W 74/06 using polling
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02

Abstract

In a wireless frequency hopping communication system, a protocol, which does not employ carrier sense or collision detect, is provided for allocating bandwidth fairly and efficiently under varying load conditions, wherein a node is permitted random access to the medium bandwidth under light loading conditions and wherein under higher loading conditions a time/bandwidth allocation is made with a portion of the allocation dedicated to inband backhaul tasks by introducing a form of polling, the size of the reserved time/bandwidth allocation being selected based on traffic pattern. Under such heavy load conditions, non-slave traffic is allocated bandwidth in slots as pseudo-slave packets to guarantee a share of the bandwidth. Depending on the activity of the population of packets, including responsiveness and trend of responsiveness, the relative size of the slots is determined. Random access is always permitted for certain classes of packets, namely handshake packets, which are used to establish the master/slave relationships between nodes, no matter how a node is loaded. Once a master/slave relationship is established, a slave is only allowed to use the random access method to inform its master that it has data pending for transmission to the network when the node has a light load. Polling is always employed when the node at least has one active slave. According to one aspect of the invention, the size of the reserved allocation is based on a variable heartbeat of a multicast poll. Further in accordance with the invention, a handshaking between master and slave permits transition between operation in a random access mode and a polled mode.

Claims

1. In a distributed control telecommunication system, a method for transitioning a first node between a first communication protocol and a second communication protocol, said second protocol being a slave mode wherein a second node communicates data with said first node when authorized by said first node according to a polling, said method comprising the steps of:

receiving at said first node a request from said second node as a candidate slave node, communicated in said first communication protocol, to permit communication according to said second communication protocol;

anticipating at said first node a current state of said second node based on prior history of communication;

establishing at said first node a state of attachment with said second node according to said second communication protocol in order to establish a link of said first node and said second node;

polling at said first node for data communication from said second node on mutually agreed upon channels and a first time schedule via said link;

monitoring, at said first node, said link via said mutually agreed upon channels according to said first time schedule for data transmission activity; and

upon sensing a cessation of data transmission activity, polling at said first node for data communication from said second node on mutually agreed upon channels and a second time schedule via said link, said second time schedule being less frequent than said first time schedule.

2. The method according to claim 1, further including allocation time for said second node to establish links and to communicate with any node while remaining in a slave mode and in an attached state with said first node.

3. The method according to claim 2 wherein said second node can communicate and link contemporaneously according to said first communication protocol and said second communication protocol.

4. In a data communication system with distributed control of links between a plurality of nodes, a method for communicating packetized information via a common communication medium, including a plurality of channels according to a frequency hopping spread spectrum arrangement, among said plurality of nodes, said method comprising:

establishing from a first node a first link to a second node according to a first communication protocol, said first communication protocol permitting random transmissions of first addressed packets during a first time period;

establishing from a third node a second link to a fourth node according to a second communication protocol, said second communication protocol permitting transmissions of second addressed packets only according to authorization in response to a poll, said poll being invoked according to a first schedule during a second time period; and

allocating available time alternately between exclusive time for said first time period and said second time period whereby random transmissions and polled transmissions can be made contemporaneously.

5. The method according to claim 4 wherein each said node can establish a plurality of contemporaneous links and wherein said first node is also said third node, said first node being a slave to control of said fourth node via said second link.

6. The method according to claim 4 wherein said poll is addressed less frequently to said third node in the absence of data transmission during a preceding polled transmission.

7. A data communication system with distributed control of links between a plurality of communication nodes for communicating packetized information via a common communication medium via a plurality of channels operative according to a frequency hopping spread spectrum communication arrangement among said plurality of nodes, said system comprising:

means, at least one of said plurality of communication nodes, for linking in a peer mode and contemporaneously for linking in a poll mode as a master and for allocating time of said communication arrangement between said poll mode and said peer mode;

means, at least one other of said plurality of communication nodes, for linking in said peer mode; and

means, at least one other of said plurality of communication nodes, for linking in said poll mode as a slave to a master.