Local multipoint distribution system

• US 5,809,431 A
• Filed: 12/06/1995
• Issued: 09/15/1998
• Est. Priority Date: 12/06/1995
• Status: Expired

• Current Assignee: Alcatel USA Sourcing L.P. (Nokia Corporation)
• Original Assignee: Stanford Telecommunications, Inc. (Nokia Corporation)
• Inventors: Bustamante, Herman, Chen, Horen
• Primary Examiner(s): Vo, Nguyen
• Assistant Examiner(s): Armstrong, Darnell R.
• Application Number:
  US08/574,605
• Time in Patent Office: 1,014 Days
• Field of Search: 455/33.1, 455/34.1, 455/54.1, 455/54.2, 455/86.1, 455/33.3, 455/562, 455/422, 455/425, 455/446, 455/449, 455/63, 455/69, 455/561
• US Class Current: 455/562.1
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 52/34 TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 84/14 WLL [Wireless Local Loop]; RLL [Radio Local Loop]

Abstract

A local multipoint distribution system having a head end coupled to a plurality of base stations with each base station constituting a cell. Each base station has a plurality of sector beam antennas, each sector beam antenna illuminating a predetermined sector of the cell with RF communication signals. A plurality of RF subscriber stations for each sector of a cell, with each subscriber station having a high gain antenna with a narrow beam width oriented toward the sector beam antenna oriented toward its assigned sector. Time division multiple access control is provided at each subscriber station operated such that each subscriber transmits at a time different from the other subscribers in its sector so that the subscribers in a given sector do not interfere with each others'"'"' transmissions, respectively. The power level transmitted by the subscribers are adjusted or controlled so that the subscriber signals arrive at the respective base stations at about the same power level. The cells can be hexagonally shaped and the sectors arranged such that the subscribers do not radiate directly into the three db beam width of base stations of immediately adjacent cells. Alternatively, the cells can be rectangularly shaped and the sectors of the cells arranged such that the subscribers do not radiate directly into the three db beam width of base stations of immediately adjacent cells.

Claims

1. A local multipoint distribution system comprising:

a head end coupled to a plurality of base stations, each base station constituting a cell,

each base station having a plurality of sector beam antennas,

each sector beam antenna illuminating a predetermined sector of said cell with RF communication signals,

a plurality of RF subscriber stations for each sector of a cell, each subscriber station having a high gain antenna with a narrow beam width oriented toward the sector beam antenna oriented toward its assigned sector, time division multiple access control means at each subscriber station operated such that each subscriber transmits at a time different from the other subscribers in its sector so the subscribers in a given sector do not interfere with each others transmissions, respectively,

means controlling the transmitted power level such that all subscriber signals arrive at their respective base stations at about the same power level,

means controlling the transmit signal timing such that all subscriber signals arrive at their respective base stations at the exclusively assigned time thereby minimizing the possibilities of mutual interference and means controlling the transmit signal frequency such that all subscriber signals operate at their proper assigned frequency and are orthogonal to all other carrier frequencies received by the base station, and wherein

each subscriber station first, in order to initiate operation, is operated in a receive-mode only to detect a stable downstream frequency from a head end signal and detect any received frequency error and adjust its initial frequency of operation in accordance therewith.

2. A local multipoint distribution system comprising:

a head end coupled to a plurality of base stations, each base station constituting a cell,

each base station having a plurality of sector beam antennas,

each sector beam antenna illuminating a predetermined sector of said cell with RF communication signals, a plurality of RF subscriber stations for each sector of a cell,

each subscriber station having a high gain antenna with a narrow beam width oriented toward the sector beam antenna oriented toward its assigned sector,

time division multiple access control means at each subscriber station operated such that each subscriber transmits at a time different from the other subscribers in its sector so the subscribers in a given sector do not interfere with each others transmissions, respectively, and

means controlling the transmitted power level such that all subscriber signals arrive at their respective base stations at about the same power level

wherein each subscriber station first, in order to initiate operation, is operated in the receive mode only to detect a stable downstream frequency from a head end signal, and detect any received frequency error and adjust its initial frequency of operation in accordance therewith.

3. The local multipoint distribution system defined in claim 2 wherein said cells are hexagonally shaped and said sectors are arranged such that the subscribers do not radiate directly into the three db beam width of base stations of immediately adjacent cells.

4. The local multipoint distribution system defined in claim 2 wherein said cells are rectangularly shaped and the sectors of said cells are arranged such that the subscribers do not radiate directly into the three db beam width of base stations of immediately adjacent cells.

5. The local multipoint distribution system defined in claim 2 wherein each said subscriber station includes means to measure the power level from the base station, and means for comparing the power level from the base station with a reference and adjusting the power at which said subscriber station transmits in accordance therewith.