Metricom, Inc.

John Bettendorff

Robert L Packer

Brett D Galloway

George H Flammer

Milton Y Xu

Michael W Ritter

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.

Hybrid multiple access protocol for wireless frequency hopping

In a packet communication system, loose source routing is employed to permit communication over networks of disparate types, including geographic and path-unaware types. No information resides on a wired access point (WAP). All of the intelligence of the system resides in Name Servers, which provide opaque addresses that end nodes (radios) in a wireless cloud can use to send packets to other end nodes (radios) in other wireless clouds. (A cloud is the set of radios serviced by a particular WAP.) According to the invention, the method employs an ordered list called a path and the network address of a packet consists of such an ordered list of addresses with a 'marker' that flags the current destination of the packet and a 'direction bit' that tells which direction on the list the next destination is. Each address in the path is type-length-value (TLV) encoded. The address has preferably a 4 bit 'type' field, followed by a 4 bit 'length' field (indicating length in words) of the value, and then the actual 'value' of the address. Each address describes a 'place' that the packet must 'visit.' These 'places' may be areas which a packet must traverse, and not necessarily actual node addresses.

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San Jose, CA, United States of America

John Bettendorff