Communications: directive radio wave systems and devices (e.g. – Directive – Including polarized signal communication transmitter or...
Reexamination Certificate
1999-05-07
2001-10-16
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including polarized signal communication transmitter or...
C342S361000, C342S368000, C342S371000, C342S373000, C342S378000
Reexamination Certificate
active
06304214
ABSTRACT:
FIELD OF INVENTION
This invention relates generally to an antenna array system for use in a wireless communications system.
BACKGROUND
Certain conventional antenna systems that adapt radiation patterns to meet conditions in a wireless communication system are referred to as “smart antennas” or “adaptive antenna arrays”. Typically, an adaptive antenna array uses a group of receivers to determine a suitable radiation pattern that maximizes the received signal strength of an uplink transmission. If multiple receivers are mounted with the antenna system on a tower-top, replacement and repair of the antenna system becomes difficult and costly. Further, many conventional adaptive antennas only provide increased uplink receiver performance without any corresponding benefit for downlink transmission. Thus, a need exists for a reliable antenna system that provides enhanced performance for both uplink and downlink signals in a wireless communications system.
Conventional adaptive arrays for uplink reception may be used in conjunction with a separate switched, fixed beam system for downlink transmission. For example, certain antenna systems use a “sub-sectored” approach for uplink reception as a mechanism for making the correct switching choice for a related downlink transmission. However, using multiple antenna arrays may exceed the limits of available mounting space. Moreover, using multiple antennas may increase transmission line, duplexer, cable, and other hardware requirements.
To simplify antenna design, some adaptive reception antennas balance their reception improvement by merely increasing the base station's downlink power for transmission. The power increase not only places a burden on the base station's amplifier system for range extension, but also does nothing to improve the signal-to-interference (S/I) ratio. An improvement in the S/I ratio may afford an increase in the traffic capacity or frequency-reuse density. Thus, a need exists for fully adaptive pattern shaping of downlink transmission to enhance the signal-to-interference ratio of the downlink signal.
SUMMARY OF THE INVENTION
In accordance with the invention, an antenna array system is capable of serving a base station for both uplink reception and downlink transmission. The antenna array system includes a first array and a second array spaced apart from the first array. The first array represents a transmit array for downlink transmissions, while a combination of the first array and the second array are referred to as a diversity arrangement for uplink reception.
In one aspect of the invention, the antenna system includes a suitable number and spatial arrangement of antenna elements to avoid lobe definition problems, while maintaining adequate decorrelation in received signals (received at the first array and the second array) to combat fast fading. In another aspect of the invention, both uplink signal-to-interference (S/I) and downlink S/I are enhanced by using adaptive radiation techniques in both the transmit mode and the receive mode. Because common antenna components are used both for the transmit and the receive mode, the antenna array system minimizes the required ancillary equipment, such as antennas, transmission lines, hardware, connectors, and monitoring receivers.
REFERENCES:
patent: 4882588 (1989-11-01), Renshaw et al.
patent: 5481570 (1996-01-01), Winters
patent: 5539407 (1996-07-01), Scholz
patent: 5675285 (1997-10-01), Winters
patent: 5819168 (1998-10-01), Golden et al.
Aiken Richard Thomas
Benning Roger David
Solondz Max Aaron
Ziesse Norman Gerard
Gregory Bernarr E.
Lucent Technologies - Inc.
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