Cellular radio communication system, radio base station apparatus and radio terminal unit
In a cellular radio communication system including of multi-antenna base stations, to make effective use of the reduced interference in supposing the use of beam form and avoid the interference in an adjacent station even if a space multiplex and the beam form are mixed. Frequencies intended for the cell edge in an FFR are classified into frequencies for space multiplex and a frequency for beam form. Thereby, a frequency at which the interference is reduced by the beam form is fixed. A frequency intended for the cell center is in a frequency band and signals are transmitted from three base stations.
1. A cellular radio communication system comprising a radio base station apparatus for making any one of a space multiplex transmission and a beam form transmission using a plurality of antennas and a plurality of radio terminal units, each radio base station apparatus,
(i) separating communicable frequency band in the cellular radio communication system to:
a first frequency band assigned to the radio terminal unit in the cell center, and
a second frequency band assigned to the radio terminal unit on the cell edge;
(ii) further using properly the second frequency band by separating to:
a beam form transmission of sending the same signal with an array weight multiplied to the plurality of radio terminal units from at least two or more antennas, and
multiplex transmission of sending a different or independent signal from each of at least two or more antennas to the same radio terminal unit or the plurality of radio terminal units;
wherein each radio base station apparatus specifies the information of frequency bands and transmission method in accordance with a state of each radio terminal unit; and
wherein the radio base station apparatus or the radio terminal unit changes a report content of communication quality information from the radio terminal unit, depending on the specified frequency band and the specified transmission method.
2. The cellular radio communication system according to claim 1 , wherein the radio base station apparatus judges a change of the frequency band and the transmission method from an upstream propagation path situation, generates a message including a report content of communication quality information in each mode, and notifies it to the radio terminal unit.
3. The cellular radio communication system according to claim 1 , wherein the radio base station apparatus generates a message including a designation of communication quality information in a narrow band as a report content of the communication quality information and notifies it to the radio terminal unit, when using the second frequency band.
4. The cellular radio communication system according to claim 1 , wherein the radio base station apparatus or the radio terminal unit has a sending power at the frequency band using the beam form transmission in the second frequency band that is greater than or equal to a sending power at the first frequency band and smaller than or equal to a sending power at the frequency band using the space multiplex transmission in the second frequency band.
5. The cellular radio communication system according to claim 1 , wherein the radio base station apparatus provides a channel frame divided by a time and a frequency for a resource at the frequency band using the beam form transmission in the second frequency band, and assigns a specific radio terminal unit to the channel frame or assigns an array weight to an antenna array.
6. The cellular radio communication system according to claim 1 , wherein
the radio base station apparatus sends, in accordance with a cell center mode (CC mode) in which a frequency used by the radio terminal unit is in the first frequency band or a cell edge mode (CE mode) in which a frequency used by the radio terminal unit is in the second frequency band, measurement report settings including a report content of communication quality information for a reference signal sent by each radio base station apparatus and measured by the radio terminal unit and a transition condition for mode switching between the CC mode and the CE mode to the radio terminal unit,
the radio terminal unit reports a measurement report indicating a determination result to the radio base station apparatus, if a determination is made that a measurement result of the reference signal satisfies the transition condition as indicated in the measurement report settings, and
the radio base station apparatus makes scheduling by transiting between the CC mode and the CE mode in accordance with the measurement report, and makes a communication with the radio terminal unit, using either the first frequency band or the second frequency band, based on the scheduling result.
7. The radio communication system according to claim 1 , wherein
the cell edge mode (CE mode) in which the frequency used by the radio terminal unit is in the second frequency band includes a cell edge-beam form transmission mode (CE-BF mode) and a cell edge-space multiplex transmission mode (CE-SM mode), and
the radio base station apparatus obtains a predetermined one or more of a moving speed or mobility of the radio terminal unit, quality of a propagation path, or its change, transmission efficiency, and load balance, in accordance with a propagation path situation of an upstream line from the radio terminal unit, determines a transition between the CE-BF mode and the CE-SM mode in accordance with the obtained result, makes a scheduling based on the determination, and makes a communication using the CE-BF mode and the CE-SM mode by further separating the second frequency band.
8. A base station apparatus in a cellular radio communication system comprising the radio base station apparatus for making any one of a space multiplex transmission and a beam form transmission using a plurality of antennas and a plurality of radio terminal units,
the radio base station apparatus,
(i) separating communicable frequency band in the cellular radio communication system to:
a first frequency band assigned to the radio terminal unit in the cell center, and
a second frequency band, assigned to the radio terminal unit on the cell edge;
(ii) further using properly the second frequency band by separating to:
a beam form transmission of sending the same signal with an array weight multiplied to the plurality of radio terminal units from at least two or more antennas, and
a space multiplex transmission of sending a different or independent signal from each of at least two or more antennas to the same radio terminal unit or the plurality of radio terminal units; and
specifying the information of frequency band and transmission method in accordance with a state of each radio terminal unit;
wherein the radio base station apparatus changes a report content of communication quality information from the radio terminal unit, depending on the specified frequency band and the specified transmission method.
9. The base station apparatus according to claim 8 , wherein the radio base station apparatus judges a change of the frequency band and the transmission method from an upstream propagation path situation, generates a message including a report content of communication quality information in each mode, and notifies it to the radio terminal unit.
10. The base station apparatus according to claim 8 , wherein the radio base station apparatus generates a message including a designation of communication quality information in a narrow band as a report content of the communication quality information and notifies it to the radio terminal unit, when using the second frequency band.
11. The base station apparatus according to claim 8 , wherein the radio base station apparatus has a sending power at the frequency band using the beam form transmission in the second frequency band that is greater than or equal to a sending power at the first frequency band and smaller than or equal to a sending power at the frequency band using the space multiplex transmission in the second frequency band.
12. The base station apparatus according to claim 8 , wherein the radio base station apparatus provides a channel frame divided by a time and a frequency for a resource at the frequency band using the beam form transmission in the second frequency band, and assigns a specific radio terminal unit to the channel frame or assigns an array weight to an antenna array.
13. The base station apparatus according to claim 8 , wherein
the radio base station apparatus sends, in accordance with a cell center mode (CC mode) in which a frequency used by the radio terminal unit is in the first frequency band or a cell edge mode (CE mode) in which a frequency used by the radio terminal unit is in the second frequency band, measurement report settings including a report content of communication quality information for a reference signal sent by each radio base station apparatus and measured by the radio terminal unit and a transition condition for mode switching between the CC mode and the CE mode to the radio terminal unit,
the radio terminal unit reports a measurement report indicating a determination result to the radio base station apparatus, if a determination is made that a measurement result of the reference signal satisfies the transition condition as indicated in the measurement report settings, and
the radio base station apparatus makes scheduling by transiting between the CC mode and the CE mode in accordance with the measurement report, and makes a communication with the radio terminal unit, using either the first frequency band or the second frequency band, based on the scheduling result.
14. The base station apparatus according to claim 8 , wherein
the cell edge mode (CE mode) in which the frequency used by the radio terminal unit is in the second frequency band includes a cell edge-beam form transmission mode (CE-BF mode) and a cell edge-space multiplex transmission mode (CE-SM mode), and
the radio base station apparatus obtains a predetermined one or more of a moving speed or mobility of the radio terminal unit, quality of a propagation path, or its change, transmission efficiency, and load balance, in accordance with a propagation path situation of an upstream line from the radio terminal unit, determines a transition between the CE-BF mode and the CE-SM mode in accordance with the obtained result, makes a scheduling based on the determination, and makes a communication using the CE-BF mode and the CE-SM mode by further separating the second frequency band.
15. A radio terminal unit in a cellular radio communication system comprising a radio base station apparatus for making any one of a space multiplex transmission and a beam form transmission using a plurality of antennas and the plurality of radio terminal units,
by each radio base station apparatus,
(i) separating communicable frequency band in the cellular radio communication system to:
a first frequency band assigned to the radio terminal unit in the cell center, and
a second frequency band, assigned to the radio terminal unit on the cell edge;
(ii) further using properly the second frequency band by separating to:
a beam form transmission of sending the same signal with an array weight multiplied to the plurality of radio terminal units from at least two or more antennas, and
a space multiplex transmission of sending a different or independent signal from each of at least two or more antennas to the same radio terminal unit or the plurality of radio terminal units, and
wherein the radio terminal unit receives a signal sent from the radio base station in any one of the first and second frequency bands, and in any one of the beam form transmission and the space multiplex transmission, by instruction from the radio base station determined in accordance with a state of each radio terminal unit,
wherein the radio terminal unit changes a report content of communication quality information from the radio terminal unit, depending on the specified frequency band and the specified transmission method.
16. The radio terminal unit according to claim 15 , wherein the radio terminal unit has a sending power at the frequency band using the beam form transmission in the second frequency band that is greater than or equal to a sending power at the first frequency band and smaller than or equal to a sending power at the frequency band using the space multiplex transmission.
17. The radio terminal unit according to claim 15 , wherein
the cell edge mode (CE mode) in which the frequency used by the radio terminal unit is in the second frequency band includes a cell edge-beam form transmission mode (CE-BF mode) and a cell edge-space multiplex transmission mode (CE-SM mode).