Communications: directive radio wave systems and devices (e.g. – Directive – Including directive communication system
Patent
1997-12-30
1999-09-14
Hellner, Mark
Communications: directive radio wave systems and devices (e.g.,
Directive
Including directive communication system
375347, 455133, H04B 700, H01Q 1112
Patent
active
059529636
ABSTRACT:
A system for selecting an antenna from a diversity of antennas in a DECT, PWT, or TDMA-based telecommunication system is disclosed. The system combines multiple criteria to improve antenna diversity selections. The principal selection process is based on preamble diversity comparisons that operate in real-time. A preamble diversity switching circuit measures receive signal strength indicators (RSSI) from a plurality of antennas and selects the antenna that provides the highest RSSI value when the difference between the RSSI values exceeds a predetermined threshold. When the value of the RSSI difference falls below the predetermined threshold, a cyclical redundancy check process (CRC) and a vector detection process (SVD) are employed jointly. The CRC process decodes a CRC value from a signal's content and compares it to a predetermined threshold. If a CRC error is detected a first weighted function is calculated. In a first SVD process, the difference between a reference signal vector and a received signal vector is computed. If an SVD error is detected a second weighted function is calculated. When the sum of the first and second weighted factors is greater than a predetermined threshold antenna selection occurs. When the threshold is not met, diversity selections remain unchanged and control of the antenna selection process returns to the preamble diversity switching process. It should be noted, the SVD process may also be based on the gradient error vector, .gradient.f(E.sub.k,n1), which represents the magnitude of the received signal's rate of change.
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Lenzo Michael
Shen Qun
Ericsson Inc.
Hellner Mark
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