Wireless communication using beam forming and diversity
View Patent ↗A method and apparatus for wirelessly transmitting real-time data streams is described. To ensure continuous data flow, fast diversity and slow diversity can be used. Fast diversity chooses a receive antenna based on received signal parameters, such as signal strength, during the transmission header and prior to information transfer. Slow diversity stores received signal parameters from previous packets, associates the parameters with a selected antenna, and uses the parameter history to denote a “default” antenna. Additionally, receive and/or transmit beam forming can be used to maintain continuous communication between stations. Beam forming, which combines antenna signals to maximize performance, is possible when at least two transmit/receive signal processing chains are available.
1. A beam forming lookup chain in a receiver, the beam forming lookup chain comprising:
a key cache for storing a first plurality of entries, each entry including at least transmit antenna data, receive acknowledgement antenna data, transmitter address data, and a beam forming enable bit;
a coefficient aging table for storing a second plurality of entries, each entry including at least coefficient aging table valid data, key cache index data, and timestamp data; and
a coefficient cache for storing a third plurality of entries, each entry including beam forming coefficients,
wherein a transmitter address of a received packet is compared to transmitter address data in the key cache, wherein a transmitter address match indicates a key cache index, wherein the key cache index is compared to the key cache index data in the coefficient aging table, and wherein a matching, valid, non-expired key cache index in the coefficient aging table indicates a corresponding entry in the coefficient cache.
2. The beam forming lookup chain of claim 1 , wherein the second and third plurality of entries have an identical number of entries.
3. The beam forming lookup chain of claim 1 , wherein a number of the first plurality of entries is significantly more than a number of the second plurality of entries.
4. The beam forming lookup chain of claim 1 , wherein the transmitter address match means a beam forming enable bit associated with the transmitter address data is set, thereby allowing update of beam forming coefficients.