High-cross correlation dynamic channel assignment for sectorized cells

• US 5,475,864 A
• Filed: 07/19/1994
• Issued: 12/12/1995
• Est. Priority Date: 07/19/1993
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Hamabe, Kojiro
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): FAILE, ANDREW I
• Application Number:
  US08/277,333
• Time in Patent Office: 511 Days
• Field of Search: 455/33.1, 455/33.3, 455/34.1, 455/56.1, 455/62, 455/63, 379/59
• US Class Current: 455/452.2
• CPC Class Codes: H04W 16/10 Dynamic resource partitioning
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

In a cellular communication system, an array of sector antennas is provided at each cell site for respectively covering sectors of the service area of the cell site. At each cell site, undesired signals of different channels are received by each antenna, and their magnitudes are determined. One of the signals is selected from each set of signals from the antennas depending on their magnitudes to produce channel signals respectively for the different channels. A list of candidate channels is determined corresponding to those of the channel signals whose qualities are higher than a threshold. One of the candidate channels is selected from the list depending on the magnitudes of those channel signals whose qualities are higher than the threshold. The selected candidate channel is assigned to a mobile station if the selected channel has acceptable quality. Otherwise, it is discarded from the list and the attempt is repeated to select a further candidate channel.

Claims

1. In a cellular communication system comprising a mobile station and a plurality of base stations each having a plurality of antennas respectively covering sectors of the service area of the base station, a method for dynamically assigning a channel from a said base station to said mobile station, comprising the steps of:

a) receiving a plurality of undesired signals of different channels by each of said antennas of the said base station to produce a plurality of sets of antenna signals respectively corresponding to said antennas, and determining the magnitudes of the antenna signals of each set, said sets corresponding respectively to said different channels;

b) selecting one of the antenna signals from each set depending on their magnitudes to produce a plurality of channel signals respectively for said different channels;

c) evaluating qualities of the channel signals, and determining a list of candidate channels corresponding to ones of the channel signals whose qualities are higher than a predetermined threshold;

d) selecting one of the candidate channels from said list depending on the magnitudes of said ones of the channel signals;

e) determining whether the selected candidate channel has acceptable quality or not;

f) assigning said selected candidate channel to said mobile station if the selected candidate channel is determined as having acceptable quality; and

g) discarding the selected candidate channel from said list and repeating the steps (d) to (f) if the selected candidate channel is determined as not having acceptable quality.

2. A method as claimed in claim 1, wherein the magnitude of the antenna signal which is selected by the step (b) is the highest of the magnitudes of the antenna signals of each set.

3. A method as claimed in claim 1, further comprising the step of sending a signal to said mobile station indicating unavailability of channels if all the candidate channels are discarded.

4. In a cellular communication system comprising a mobile station and a plurality of base stations each having a plurality of antennas respectively covering sectors of the service area of the base station, a method for dynamically assigning a channel from a said base station to said mobile station, comprising the steps of:

a) receiving a plurality of undesired signals of different channels by said antennas of the said base station to produce a plurality of sets of antenna signals respectively corresponding to said antennas, and determining the magnitudes of the antenna signals of each set, said sets corresponding respectively to said different channels;

b) selecting a highest magnitude antenna signal from each set and identifying a first one of the antennas by which said highest magnitude antenna signal is received;

c) selecting a second highest magnitude antenna signal from each set and identifying a second one of the antennas by which said second highest magnitude antenna signal is received, said second one of the antennas having a directivity pattern located adjacent a directivity pattern of said first one of said antennas;

d) determining the angle of arrival of a signal from the directivity patterns of said first and second ones of said antennas and the magnitudes of said highest magnitude antenna signal and said second highest magnitude antenna signal, and correcting the magnitude of the highest magnitude antenna signal by the directivity pattern of one of said first and second antennas as a function of the determined angle to produce a channel signal for each set;

e) evaluating qualities of the channel signals of said sets, and determining a list of candidate channels corresponding to ones of the channel signals whose qualities are higher than a predetermined threshold;

f) selecting one of the candidate channels from said list depending on the magnitudes of said ones of the channel signals;

g) determining whether the selected candidate channel has acceptable quality or not;

h) assigning said selected candidate channel to said mobile station if the selected candidate channel is determined as having acceptable quality; and

i) discarding the selected candidate channel from said list and repeating the steps (f) to (h) if the selected candidate channel is determined as not having acceptable quality.

5. A method as claimed in claim 4, further comprising the step of sending a signal to said mobile station indicating unavailability of channels if all the candidate channels are discarded.

6. In a cellular communication system comprising a mobile station and a plurality of base stations each having a plurality of antennas respectively covering sectors of the service area of the base station, wherein unique sets of channels are allocated respectively to the antennas of said base stations which are oriented in identical directions, a method for dynamically assigning a channel from a said base station to said mobile station, comprising the steps of:

a) receiving a plurality of undesired signals of different channels by first and second ones of said antennas of the said base station to produce a plurality of sets of antenna signals respectively corresponding to said antennas, and determining the magnitudes of the antenna signals of each set, said first and second ones of said antennas being oriented in opposite directions from each other and said sets corresponding respectively to said different channels;

b) selecting a highest magnitude antenna signal from each set to produce a plurality of channel signals respectively for said channels;

c) evaluating qualities of said channel signals, and determining a list of candidate channels corresponding to ones of the channel signals whose qualities are higher than a predetermined threshold;

d) selecting one of the candidate channels from said list depending on the magnitudes of said ones of the channel signals;

e) determining whether the selected candidate channel has acceptable quality or not;

f) assigning said selected candidate channel to said mobile station if the selected candidate channel is determined as having acceptable quality; and

g) discarding the selected candidate channel from said list and repeating the steps (d) to (f) if the selected candidate channel is determined as not having acceptable quality.

7. A method as claimed in claim 6, further comprising the step of sending a signal to said mobile station indicating unavailability of channels if all the candidate channels are discarded.

8. In a cellular communication system comprising a mobile station and a plurality of base stations each having a plurality of antennas respectively covering sectors of the service area of the base station, wherein unique sets of channels are allocated respectively to the antennas of said base stations which are oriented in identical directions, a said base station having an odd number of antennas, a method for dynamically assigning a channel from the said base station to said mobile station, comprising the steps of:

a) receiving undesired signals of different channels by each of first, second and third ones of the antennas of the said base station to produce a plurality of sets of first, second and third antenna signals corresponding respectively to said first, second and third ones of said antennas, and determining the magnitudes of the antenna signals of each set, said first and second ones of the antennas having respective directivity patterns and a virtual directivity pattern which is oriented in a direction opposite to a directivity pattern of said third one of the antennas, and said sets corresponding respectively to said different channels;

b) determining the angle of arrival of a signal for each of said channels from the respective directivity patterns of said first and second ones of said antennas and the magnitudes of said first and second antenna signals of each set, and correcting the magnitude of one of the first and second antenna signals of each set having a higher magnitude by the directivity pattern of one of said first and second ones of the antennas and said virtue directivity pattern as a function of the determined angle;

c) selecting, from each set, the corrected antenna signal or the antenna signal received by said third one of the antennas depending on their relative magnitudes to produce a plurality of channel signals respectively for said different channels;

d) evaluating qualities of said channel signals and determining a list of candidate channels corresponding to ones of channel signals whose qualities are higher than a predetermined threshold;

e) selecting one of the candidate channels from said list depending on the magnitudes of said ones of the channel signals;

f) determining whether the selected candidate channel has acceptable quality or not;

g) assigning said selected candidate channel to said mobile station if the selected candidate channel is determined as having acceptable quality; and

h) discarding the selected candidate channel from said list and repeating the steps (e) to (g) if the selected candidate channel is determined as not having acceptable quality.

9. A method as claimed in claim 8, further comprising the step of sending a signal to said mobile station indicating unavailability of channels if all the candidate channels are discarded.