US 5,204,855 AGranted

Skywave adaptable network transceiver apparatus

AssigneeRockwell International Corporation

InventorsMelvin G. Bebee, Bill C. Miller, Daniel O. Weddle, W. P. Werth, C. David Young

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Abstract

In a skywave adaptable communications network, the time required to initiate communications between two transceivers can often be an important factor where the propagation characteristics of signals at various frequencies vary drastically with time. The present invention improved upon the prior art by accepting the first frequency that it hears as a communication frequency when two nodes are attempting to communicate from a known list of frequencies to be transmitted at known times. The system then adaptively changes to better quality signals as these better quality signals are received, analyzed and compared with present working frequency signals.

Claims22

Dependent claims

A node in a network of operationally identical nodes where each node can directly communicate with a predetermined number of neighbor nodes on a time multiplexed basis with each neighbor being assigned separate and exclusive transmitting and receiving time slots where the communication carrier frequencies used may be different for transmitting and receiving as well as different for each neighbor, where a set of transmitting and receiving time slots for each neighbor is defined as a cycle and where the time slots comprise probe and traffic portions, comprising in combination:

clock means for maintaining accurate time relative to a common reference of all nodes;
list means for storing a frequency-time related list of probe frequencies to be used for any given time between nodes with the number of cycles required to transmit each of the probe frequencies on said list being defined as an epoch;
transmission means, connected to said clock means, for transmitting a different frequency probe each cycle during a probe preamble portion of the transmitting time slot, in accordance with said frequency-time related list, with no frequency being repeated until an epoch is completed;
reception means for detecting probes transmitted from each of said predetermined neighbor nodes each cycle at a frequency as defined in said frequency-time related list;
means, connected to said list means, said transmission means and said reception means, for at any time calculating the next frequency to be used from said frequency-time related list thereby permitting the joining of the network asynchronously by any already designated neighbor at any time;
measurement means, connected to said transmission and reception means, for adding a frequency used during the successful reception of a probe to a stored set of working frequencies and storing quality measurements associated with that successful reception frequency;
control data means, associated with said transmission means, for using at least some of the transmitting time slot after a probe preamble to transmit control data;
and
information transfer means, connected to said transmission means, for using the other of said first and second portions of the transmitting time slot to carry traffic information subsequent to recognizing link-up with a given neighbor node.

6 more elements

A method by which nodes in a network each link up with, that is, establish traffic communication conditions with, neighbor nodes on a time multiplexed basis, with each neighbor node being assigned separate transmitting and receiving time slots, wherein the communication carrier frequencies used may be different for transmitting and receiving, as well as different for each neighbor, with a set of transmitting and receiving slots for each neighbor being defined as a cycle, and wherein each time slot includes first and second portions, with one of the portions being reserved for probe signals, comprising the steps of:

maintaining an accurate time relative to a common reference used by all the neighbor nodes;
referring to said accurate time and selecting for each cycle a probe frequency from a frequency-time related list of frequencies to be used between nodes at any given time;
transmitting a probe signal of a different one of the list frequencies for each cycle, said probe signal including a preamble and control data in the portion of the transmitting slot reserved for probe signals;
receiving probe signals from neighbor nodes on frequencies in accordance with said list and said accurate time and thereby permitting said neighbor nodes to asynchronously begin the process of linking up with other neighbor nodes;
storing the transmission frequency of successfully received probe signals in a set of working frequencies, along with a quality measure associated with the stored frequency;
announcing, in at least one of said transmission time slots, a successful reception of a signal transmitted by a neighbor node;
recognizing a link up with a particular neighbor node as signals transmitted to and from the particular node are successfully received;
and
transmitting traffic signals in the other of said first and second portions of the transmitting slot, after recognizing a link up.

6 more elements

Dependencies are inferred from the claim text.