JP3563722B2 - Wireless communication control device, wireless channel allocation method, program, and recording medium - Google Patents

Description

【００３０】
上記と同様に、無線チャネルＢを同時に確立できる無線チャネルＢの最大数をＮとする。そして、時点ｘにおいて無線チャネルＢを同時に確立している移動局１０の数をｂとする。すると、時点ｘにおける無線チャネルＢのスループットＴ_ｂは、次式（２）で表すことができる。
【数２】

【００３１】
ここで、移動局１０のデータ通信において、高速通信モードと低速通信モードとの切り替え点は、Ｔ_ａ＝Ｔ_ｂという条件が成立する点である。時点ｘにおける無線チャネルＡの使用率をρ_ａ（＝ａ／Ｎ）とし、無線チャネルＢの使用率をρ_ｂ（＝ｂ／Ｎ）とすると、通信モードの切り替え点はｔ_ａ（１−ρ_ａ）＝ｔ_ｂ（１−ρ_ｂ）と表すことができ、これを変形して次式（３）が導かれる。
【数３】

【００３２】
式（３）より、無線チャネルＡを介して通信を行う移動局１０の数が（ｔ_ａ−ｔ_ｂ）Ｎ／ｔ_ａ台に達するまで、制御局１２は、移動局１０に無線チャネルＡを割り当てるようにすればよいことがわかる。この場合、移動局１０は、必ず高速通信モードによって通信を行うことができる。
【００３３】
一方、無線チャネルＡを介して通信を行う移動局の数が（ｔ_a−ｔ_b）Ｎ／ｔ_a台を超えた場合には、制御局１２は、その超過以降における無線チャネルＡおよび無線チャネルＢとの比がｔ _b ：ｔ _a となるように、移動局１０に無線チャネルを割り当てるようにする。そうすることで、各無線チャネルのスループットにあわせて移動局１０に無線チャネルを割り当てることができ、移動体通信システム１の通信効率を維持できる。また、低速通信モードで通信しなければならない無線チャネルを移動局１０に割り当てることを最小限に抑えることができる。
【００３４】
移動局１０に、ｔ _b ：ｔ _a の割合で無線チャネルを割り当てるということを別様に表現したのが、次式（４）である。
【数４】

（ただし、δ＝（ｔ_a−ｔ_b）Ｎ／ｔ_a）
つまり、無線チャネルＡを確立して通信中の移動局の数が（ｔ_a−ｔ_b）Ｎ／ｔ_a台を超えた場合には、この式（４）に示される関係を満たすように、移動局１０に無線チャネルを割り当てればよい。
【００３５】
制御局１２のＲＯＭ１２１に記憶されているスループット算出手順を記録したプログラムとは、上述の原理に従った演算を行うためのプログラムである。ＣＰＵ１２０は、このプログラムに従った演算を行い、その結果に基づいて、移動局１０に割り当てる無線チャネルを決定している。
【００３６】
＜２．実施形態の動作＞
次に、本実施形態の制御局１２が、移動局１０に無線チャネルを割り当てる動作を具体的に説明する。
ここでは、無線チャネルＡにおける上りチャネルと下りチャネルとの周波数間隔は、移動局１０が弁別可能な程度、すなわち高速通信モードで通信可能な間隔であるとする。その結果、無線チャネルＡを利用した場合の移動局１０の伝送能力は２８．８ｋ／ｂｐｓとなっているとする。
また、無線チャネルＢにおける上りチャネルと下りチャネルとの周波数間隔は、移動局１０が弁別不可能な程度、すなわち低速通信モードで通信せざるを得ない間隔であるとする。その結果、無線チャネルＢを利用した場合の移動局１０の伝送能力は９．６ｋ／ｂｐｓとなっているとする。
そして、無線チャネルＡおよび無線チャネルＢはともに、時分割多重によって同時に３００台までの移動局１０によって利用可能であるとする。
【００３７】
図５は、移動局１０と基地局１１との間に無線チャネルを確立する際の、制御局１２の動作を示すフローチャートである。
まず、移動局１０からのデータ通信開始を要求する信号を検知すると（ステップＳ１００）、制御局１２の監視制御部１２４は、移動局１０の認証処理を行う（ステップＳ１０１）。この認証が成立すると（ステップＳ１０１においてＹｅｓ）、制御局１２は処理をステップＳ１０２に移し、移動局１０に割り当てるべき無線チャネルを決定する動作に入る。
【００３８】
制御局１２は、無線チャネルＡを確立して通信中の移動局１０の数ａが、上記の変数δ以下である場合に（ステップＳ１０２においてＹｅｓ）、無線チャネルＡを、移動局１０に割り当てる（ステップＳ１０３）。この結果、移動局１０と基地局１１との間に無線チャネルＡが確立されると、移動局１０は無線チャネルＡの上りチャネルと下りチャネルとを同時に用いてデータ送受信を行い、高速に通信することができる。
【００３９】
図６は、ａ＜δで表される関係が満たされる状態を示す概念図である。無線チャネルＡを同時に利用可能な移動局１０の総数は３００台であり、無線チャネルＢについても同様であるため、δ＝（ｔ_ａ−ｔ_ｂ）Ｎ／ｔ_ａ≒２００（台）となる。したがって、図６に示すように、無線チャネルＡを同時に利用している移動局１０の総数が２００台未満である場合には、制御局１２は、基地局１１との間で無線チャネルＡを確立する移動局１０が２００台に達するまで、新たにデータ通信を要求してくる移動局１０に対して、無線チャネルＡを割り当てる。
【００４０】
やがて、基地局１１との間で同時に無線チャネルＡを確立する移動局１０が２００台に達してしまったとする。図７は、ａ＝δとなった状態を示す概念図である。この状態からさらに移動局１０に無線チャネルＡを割り当てることも可能であるが、そうすると、無線チャネルＢが空いているにも関わらず、無線チャネルＡを利用する移動局１０の数が多過ぎる状態になってしまい、移動体通信システム１全体の通信効率が低下する。そのため、移動局１０に、無線チャネルＡに加えて、無線チャネルＢを割り当てるようにする。
【００４１】
無線チャネルＡが図７に示される状態に至ったことを検知した制御局１２は（ステップＳ１０２においてＮｏ）、処理をステップＳ１０４に移し、新たに無線チャネル割り当てを要求する移動局１０に対して、無線チャネルＢを割り当てるべきか否かを判別する（ステップＳ１０４）。ここで、無線チャネルＢの伝送能力は、無線チャネルＡの伝送能力の１／３である。そこで、制御局１２は、移動局１０との間に新たに無線チャネルを確立する場合、無線チャネルＡと無線チャネルＢとの比が１：３になるように基地局１１を制御する。
【００４２】
図８は、無線チャネルＡを確立する移動局１０の数ａが、ａ＞δとなった状態を示す概念図である。ここで、無線チャネルＡを確立する移動局１０の数ａと、無線チャネルＢを確立する移動局１０の数ｂとの比を１：３とするために、制御局１２は、基地局１１との間で無線チャネルＢを確立する移動局１０の数ｂが３（ａ−δ）未満である間（ステップＳ１０４においてＹｅｓ）、新たに無線チャネルの確立を要求する移動局１０に対して、無線チャネルＢを割り当てる（ステップＳ１０５）。
【００４３】
そして、さらに無線チャネルを確立する移動局１０の数が増えつづけ、無線チャネルＢを確立する移動局１０の数ｂが３（ａ−δ）以上になると、（ステップＳ１０４においてＮｏ）、制御局１２は、新たにデータ通信の開始を要求する移動局１０に対して、無線チャネルＡを割り当てる。このように制御することで、無線ゾーン１１０が輻輳してきた場合であってもデータ通信の効率を維持すると共に、移動局１０に可能な限り高速通信可能な無線チャネルを割り当てることが可能となる。
【００４４】
＜３．実施形態の効果＞
以上、説明したように、本実施形態の移動体通信システム１では、各無線チャネルによって通信を行っている移動局１０の数を平均化するように無線チャネルを割り当てるのではなく、各無線チャネルの上りチャネルおよび下りチャネルの周波数間隔に基づくスループットを基準として移動局１０に無線チャネルを割り当てる。そのため、移動局１０は、高速通信モードによって通信することのできる可能性が高まる。そして、移動局１０の通信効率の向上に従属して、移動体通信システム１の通信効率もまた向上する。
【００４５】
＜変形例＞
なお、本発明の制御局および移動局への無線チャネル割り当て方法は、上述の実施形態に限定されるものではなく、本発明の技術的思想の範囲内で種々の変更を加えることが可能である。
【００４６】
（１）上述の実施形態では、無線チャネルを利用する移動局の数に基づいてスループットを算出し、その結果に基づいて、新たに無線チャネルの割り当てを要求する移動局を、どの無線チャネルに割り当てるかを決定する態様をとって説明を行った。しかし、無線チャネルのスループット算出は、移動局の数に基づくものでなくても構わない。例えば、無線チャネルのスループット算出は、無線チャネルの使用率に基づくものであっても構わない。以下に、無線チャネルＣおよびＤを例にとって本変形例の原理を説明する。
【００４７】
まず、無線チャネルのトラヒックが、Ｍ／Ｍ／１モデルに適合するものであると仮定すると、この無線チャネルの正規化平均待ち時間は、次式（５）で表される。
【数５】

（ただし、ρ＝無線チャネル使用率）
【００４８】
すると、無線チャネル使用率ρの場合における正規化平均スループットＴ_ｈは、次式（６）で表される。
【数６】

【００４９】
そして、無線チャネルの伝送能力をｔ _c とすると、無線チャネルＣのスループットＴ_cは、次式（７）で表される。
【数７】

【００５０】
上記と同様に、無線チャネルＤの伝送能力をｔ_ｄとすると、無線チャネルＤのスループットＴ_ｄは、次式（８）によって表される。ただし、ｔ_ｃ＞ｔ_ｄとする。
【数８】

【００５１】
ここで、移動局１０のデータ通信において、高速通信モードと低速通信モードとの切り替えが行われるのは、Ｔ_ｃ＝Ｔ_ｄという条件が成立する点である。したがって、上記の式（７）および式（８）から、通信モードの切り替え点はｔ_ｃ（１−ρ_ｃ）＝ｔ_ｄ（１−ρ_ｄ）と表すことができ、これを変形して、次式（９）が導かれる。
【数９】

【００５２】
式（９）より、無線チャネルＣの使用率ρ_ｃが（ｔ_ｃ−ｔ_ｄ）／ｔ_ｃに達するまでは、制御部１２は、移動局１０に無線チャネルＣを割り当てるようにすればよいことがわかる。この場合、移動局１０は、必ず高速通信モードによって通信を行うことができる。
【００５３】
また、無線チャネルＣの使用率ρ_ｃが、ｔ_ｃ−ｔ_ｄで表される数値を超えている場合には、無線チャネルＣの伝送能力ｔ_ｃと無線チャネルＤの伝送能力ｔ_ｄとの比に基づき、ｔ_ｃ：ｔ_ｄとなるように、移動局１０に無線チャネルを割り当てるようにする。そうすることで、無線チャネルＣの伝送能力および無線チャネルＤの伝送能力にあわせて移動局１０に無線チャネルを割り当てることができ、低速通信モードで通信しなければならない無線チャネルを移動局１０に割り当てることを最小限に抑えることができる。
【００５４】
移動局１０に、ｔ_ｃ：ｔ_ｄの割合で無線チャネルを割り当てるということは、次式（１０）に示される関係を満たすように、移動局１０に無線チャネルを割り当てるということである。
【数１０】

（ただし、γ＝（ｔ_ｃ−ｔ_ｄ）／ｔ_ｃ）
【００５５】
上記の原理により移動局１０への無線チャネル割り当てを制御することも可能である。したがって、制御局１２のＲＯＭ１２１に記憶されるプログラムとして、上述の原理に基づいて無線チャネルのスループットを算出する手順を記述したものを記憶し、このプログラムに記述された手順をＣＰＵ１２０に実行させてもよい。要は、制御局１２が無線チャネルのスループットを算出し、その算出結果に基づいて、移動局１０に無線チャネルを割り当てる態様であれば、どのような態様であっても構わない。
【００５６】
（２）上述の実施形態においては、移動局としてＰＤＣ方式を採用するものを例にとって説明を行ったが、移動局は必ずしもＰＤＣ方式を採用するものである必要はない。例えば、ＧＳＭ（Ｇｌｏｂａｌ Ｓｙｓｔｅｍ ｆｏｒ Ｍｏｂｉｌｅ ｃｏｍｍｕｎｉｃａｔｉｏｎ）方式を採用するものであっても構わないし、ＰＨＳ（Ｐｅｒｓｏｎａｌ Ｈａｎｄｙｐｈｏｎｅ Ｓｙｓｔｅｍ）であってもよい。要は、基地局との間で無線チャネルを確立する際、上りチャネルと下りチャネルに周波数差があり、その周波数差に応じて移動局の通信速度が変化するシステムであれば、どのようなものであっても本発明を適用することが可能である。
【００５７】
【発明の効果】
以上、説明したように、本発明の無線通信制御装置および無線チャネル割り当て方法では、移動局への無線チャネルの割り当てを各無線チャネルのスループットに基づいて行うため、移動局に可能な限り高速通信することのできる無線チャネルを割り当てることができる。
【図面の簡単な説明】
【図１】移動体通信システム１の全体構成を示すブロック図である。
【図２】高速通信モードでの移動局１０の通信状態を示す概念図である。
【図３】低速通信モードでの移動局１０の通信状態を示す概念図である。
【図４】制御局１２の電気的構成を示すブロック図である。
【図５】移動局１０と基地局１１との間に確立するチャネルの周波数を選択する動作を示すフローチャートである。
【図６】ａ＜δで表される関係が満たされる状態を示す概念図である。
【図７】ａ＝δとなった状態を示す概念図である。
【図８】ａ＞δで表される関係が満たされる状態を示す概念図である。
【符号の説明】
１０…移動局、１１…基地局、１２…制御局、１２０…ＣＰＵ、１２４…監視制御部。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radio communication control device and a radio channel allocation method for allocating a radio channel to a mobile station whose communication speed changes according to a frequency difference between an uplink channel and a downlink channel.
[0002]
[Prior art]
Among mobile stations performing communication by the TDMA (Time Division Multiple Access) method, a high-speed communication mode capable of simultaneously transmitting and receiving data and a timing of transmitting and receiving data are shifted. There is a mobile station that switches between two communication modes, that is, a low-speed communication mode in which communication is performed with a mobile station. This type of mobile station switches the communication mode based on the frequency interval between the uplink channel and the downlink channel in the allocated radio channel.
[0003]
In order to simultaneously transmit and receive data, the mobile station itself erroneously receives radio waves transmitted by the mobile station using the uplink channel. Requires a device to discriminate. However, if frequency discrimination is performed too strictly, the size of the apparatus increases, and as a result, the size of the mobile station increases. Therefore, the mobile station performs data transmission and reception simultaneously when the frequency of the uplink channel and the frequency of the downlink channel are separated by a predetermined interval or more, and when the frequency is less than the predetermined interval, the timing of transmission and reception of data. The size of the device is maintained by taking the action of shifting the position. Therefore, in the allocated radio channel, if the frequency interval between the uplink channel and the downlink channel is wide, the mobile station can perform communication in the high-speed communication mode. I have to communicate in mode.
[0004]
Meanwhile, the radio channel allocated to the mobile station is determined by the control station when the mobile station requests the base station to start data communication. At this time, if a wireless channel capable of communicating in the high-speed communication mode is allocated to the mobile station capable of switching the communication mode, the mobile station can perform data communication efficiently.
[0005]
[Problems to be solved by the invention]
However, in the related art, the assignment of wireless channels to mobile stations has been controlled so that the number of mobile stations sharing each wireless channel by time division is averaged. For this reason, for example, even if a wireless channel that allows the mobile station to communicate using the high-speed communication mode is available, a wireless channel that must communicate using the low-speed communication mode may be assigned. In such a case, the mobile station could not perform its communication sufficiently.
[0006]
In view of such circumstances, the present invention provides a wireless communication control device, a wireless channel assignment method, a program, and a recording medium that can assign a wireless channel capable of high-speed communication to a mobile station as much as possible.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention provides a throughput calculation unit that calculates a throughput of a wireless channel based on a transmission capability and a channel usage rate of a mobile station, a first wireless channel, and a first wireless channel. Calculating means for calculating the channel usage rate of the first wireless channel when the throughput of the first wireless channel is equal to the throughput of the second wireless channel for the second wireless channel having a low transmission capability of the mobile station. Assigning the first radio channel to the mobile station until the channel usage rate calculated by the calculation means is reached for the mobile station that newly requests the allocation of the radio channel; After the time when the throughput of the second radio channel becomes equal to that of the second radio channel, each time a new mobile station requesting radio channel allocation appears, The high radio channel throughput of the first radio channel and the second radio channel to provide a radio communication control apparatus characterized by having an allocating means for allocating to the mobile station.
[0008]
With such a wireless communication control device, the mobile station can establish a wireless channel with the highest throughput, and does not unnecessarily reduce its data transmission capability.
[0009]
Here, it is preferable to have a means for calculating the channel usage rate based on the mobile stations using the radio channel and the maximum number of mobile stations to which the radio channel can be allocated.
[0010]
Further, the present invention provides a first step of calculating a throughput of a wireless channel based on a transmission capability and a channel usage rate of a mobile station, and the first wireless channel and the transmission of the mobile station more than the first wireless channel. A second step of obtaining a channel usage rate of the first wireless channel when the throughput of the first wireless channel is equal to the throughput of the second wireless channel with respect to the second wireless channel having low capability; Assigning the first wireless channel to the mobile station until the channel usage rate determined in the second step is reached, and assigning the first wireless channel to the mobile station. After the point in time when the throughput of the second radio channel becomes equal, each time a mobile station requesting a new radio channel assignment appears, the first radio channel is assigned. Providing a radio channel assignment method characterized by a step of allocating a higher radio channel throughput in the mobile station of channel and the second radio channel.
[0011]
With this radio channel assignment method, the mobile station can establish a radio channel with the highest throughput, and does not unnecessarily reduce its data transmission capability.
[0012]
Here, it is preferable that the channel usage rate is determined based on the mobile station currently using the radio channel and the maximum number of mobile stations to which the radio channel can be allocated.
[0013]
The present invention also provides a computer with a throughput calculation function for calculating a throughput of a wireless channel based on a transmission capability and a channel usage rate of a mobile station, a first wireless channel, and a mobile station that is more than the first wireless channel. A second wireless channel having a low transmission capacity, a calculation function for calculating a channel usage rate of the first wireless channel when the throughputs of the first wireless channel and the second wireless channel are equal, Assigning the first wireless channel to the mobile station until the channel usage rate calculated by the calculation unit is reached, and requesting the mobile station to request the assignment of the wireless channel to the mobile station. After the point in time when the throughputs of the wireless channels 2 become equal, each time a mobile station requesting a new wireless channel allocation appears, Providing a program for implementing the allocation function to allocate a higher radio channel throughput in the mobile station of the radio channel and the second radio channel.
[0014]
Such a program allows the mobile station to establish a wireless channel with the highest throughput and does not unnecessarily reduce its data transmission capability.
[0015]
Here, it is preferable that the channel usage rate is determined based on the mobile station currently using the radio channel and the maximum number of mobile stations to which the radio channel can be allocated.
[0016]
Further, the present invention provides a computer-readable recording medium recording the above-mentioned program..
[0017]
Such a recording medium facilitates backup and distribution of the program.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
<1. Configuration of Embodiment>
FIG. 1 is a conceptual diagram showing an overall configuration of a mobile communication system 1 employing a PDC (Personal Digital Cell) method.
As shown in FIG. 1, the mobile communication system 1 includes a mobile station 10, a base station 11, and a control station 12. The base station 11 outputs a radio wave of a predetermined level, and forms a wireless zone 110 corresponding to the reach of the radio wave. FIG. 1 illustrates an example in which the mobile station 10 is located in the wireless zone 110. Although illustration is omitted, it is assumed that a plurality of mobile stations 10 are located in the wireless zone 110.
[0019]
The mobile station 10 and the base station 11 located in the wireless zone 110 perform wireless communication by a TDMA (Time Division Multiple Access) method. The base station 11 can use a plurality of wireless channels, and allocates one of the wireless channels to each mobile station 10. This radio channel means a bidirectional communication channel, and is used for an uplink channel used for data transmission from the mobile station 10 to the base station 11 and for the mobile station 10 to receive data from the base station 11. It is a set with the downlink channel to be used.
[0020]
When the frequency interval between the uplink channel and the downlink channel is large in the allocated radio channel, the mobile station 10 uses the slots of the uplink channel and the downlink channel at the same timing, and performs high-speed communication for simultaneously transmitting and receiving data. Communicate in mode. When the frequency interval between the uplink channel and the downlink channel is narrow, the mobile station 10 performs communication in a low-speed communication mode in which data transmission and reception are performed at different timings.
[0021]
FIG. 2 is a conceptual diagram illustrating a communication state of the mobile station 10 in the high-speed communication mode. As described above, since the mobile station 10 can simultaneously transmit and receive data in the high-speed communication mode, it is possible to perform communication using the uplink channel and the downlink channel simultaneously. In FIG. 2, one frame is divided into three slots, and all three slots are used as a downlink channel, and one of the three slots is used as an uplink channel.
[0022]
On the other hand, FIG. 3 is a conceptual diagram showing a communication state of the mobile station 10 in the low-speed communication mode. As described above, in the low-speed communication mode, the mobile station 10 cannot simultaneously transmit and receive data, so that the communication speed is lower than in the high-speed communication mode. FIG. 3 illustrates communication using one of the three slots for both the uplink channel and the downlink channel. As described above, the communication speed of the mobile station 10 greatly changes depending on the frequency interval of the assigned wireless channel.
[0023]
The device that performs the process of allocating the radio channel to the mobile station 10 is the control station 12 connected to the base station 11. The control station 12 calculates the channel throughput in consideration of the frequency interval of each radio channel, and selects a radio channel used for communication between the mobile station 10 and the base station 11 based on the calculation result. Then, the control station 12 allocates the selected radio channel to the mobile station 10. Although the control station 12 is shown as a separate device from the base station 11 in FIG. 1, it may be installed in the base station 11 or in an exchange (not shown).
[0024]
FIG. 4 is a block diagram showing an electrical configuration of the control station 12. As shown in FIG. 4, the control station 12 includes a CPU 120, a ROM 121, a RAM 122, an external interface 123, and a monitoring control unit 124.
[0025]
The CPU 120 controls each unit included in the control station 12 according to various control programs stored in the ROM 121. The ROM 121 stores a control program used for various controls in the control station 12 and a program recording a wireless channel throughput calculation procedure. The RAM 122 is used as a temporary work area of the CPU 120. The external interface 123 is an interface for converting various signals transmitted and received between the control station 12 and the base station 11 and between the control station 12 and an exchange (not shown).
[0026]
The monitoring control unit 124 can identify the frequency interval between the uplink channel and the downlink channel in the radio channel, and knows how many mobile stations 10 are allocated to which radio channel. When detecting that the mobile station 10 has requested the assignment of the wireless channel, the monitoring control unit 124 outputs an interrupt signal to the CPU 120 to instruct the CPU 120 to calculate the throughput of the wireless channel.
[0027]
The CPU 120 performs the operation of calculating the throughput of each wireless channel that can be assigned to the mobile station 10 using the interrupt signal output from the monitoring control unit 124 as a trigger. Then, based on the calculation result, the CPU 120 allocates the wireless channel having the highest throughput to the mobile station 10.
[0028]
Here, taking the wireless channels A and B as an example, the principle in which the CPU 120 calculates the throughput of the wireless channel that can be assigned to the mobile station 10 will be described. As a premise of the description, it is assumed that the mobile station 10 can identify the frequency interval between the uplink channel and the downlink channel in the wireless channel A, and as a result, the mobile station 10 can perform high-speed communication when the wireless channel A is established. Then, the data transmission capability of the mobile station 10 by establishing the wireless channel A is t_aIt expresses.
Similarly, it is assumed that the mobile station 10 cannot identify the frequency interval between the uplink channel and the downlink channel in the wireless channel B, and as a result, the mobile station 10 has to perform low-speed communication when the wireless channel B is established. Then, the data transmission capability of the mobile station 10 by establishing the wireless channel B is represented by t_bIt expresses.
At this time, t_a> T_bThe relationship holds.
[0029]
First, since the wireless channel A is time-division multiplexed, a plurality of mobile stations 10 can establish the wireless channel A at the same time. At this time, the maximum number of the mobile stations 10 that can establish the wireless channel A is N, and the number of the mobile stations 10 that are simultaneously establishing the wireless channel A at a certain time x is a. Then, the throughput T of the wireless channel A at the time point x_aCan be expressed by the following equation (1).
(Equation 1)

[0030]
In the same manner as described above, the maximum number of the wireless channels B that can simultaneously establish the wireless channels B is N. Then, the number of mobile stations 10 simultaneously establishing the radio channel B at the time point x is set to b. Then, the throughput T of the wireless channel B at the time point x_bCan be expressed by the following equation (2).
(Equation 2)

[0031]
Here, in the data communication of the mobile station 10, the switching point between the high-speed communication mode and the low-speed communication mode is T_a= T_bThat is, the condition is satisfied. Let ρ be the usage rate of wireless channel A at time x._a(= A / N), and the usage rate of the wireless channel B is ρ_b(= B / N), the switching point of the communication mode is t_a(1-ρ_a) = T_b(1-ρ_b), Which can be transformed into the following equation (3).
(Equation 3)

[0032]
From equation (3), the number of mobile stations 10 communicating via wireless channel A is (t_a-T_b) N / t_aIt is understood that the control station 12 may allocate the radio channel A to the mobile station 10 until the number of mobile stations reaches the number. In this case, the mobile station 10 can always perform communication in the high-speed communication mode.
[0033]
On the other hand, the number of mobile stations communicating via the wireless channel A is (t_a-T_b) N / t_aIf the number exceeds the number, the control station 12 determines that the ratio between the wireless channel A and the wireless channel B after the excess is exceeded.t _b : T _a A wireless channel is assigned to the mobile station 10 such that By doing so, a wireless channel can be allocated to the mobile station 10 according to the throughput of each wireless channel, and the communication efficiency of the mobile communication system 1 can be maintained. In addition, it is possible to minimize the assignment of the radio channel, which must communicate in the low-speed communication mode, to the mobile station 10.
[0034]
In the mobile station 10,t _b : T _a The following expression (4) expresses that the assignment of the wireless channel at the ratio of is expressed in another way.
(Equation 4)

(However, δ = (t_a-T_b) N / t_a)
That is, the number of mobile stations communicating with establishing the wireless channel A is (t_a-T_b) N / t_aWhen the number of mobile stations exceeds the number of mobile stations, a radio channel may be allocated to the mobile station 10 so as to satisfy the relationship shown in the equation (4).
[0035]
The program that records the throughput calculation procedure stored in the ROM 121 of the control station 12 is a program for performing calculations according to the above-described principle. The CPU 120 performs an operation according to this program, and determines a radio channel to be allocated to the mobile station 10 based on the result.
[0036]
<2. Operation of Embodiment>
Next, an operation in which the control station 12 of the present embodiment allocates a wireless channel to the mobile station 10 will be specifically described.
Here, it is assumed that the frequency interval between the uplink channel and the downlink channel in the wireless channel A is such that the mobile station 10 can discriminate, that is, the interval at which communication is possible in the high-speed communication mode. As a result, it is assumed that the transmission capability of the mobile station 10 when using the wireless channel A is 28.8 k / bps.
It is also assumed that the frequency interval between the uplink channel and the downlink channel in the wireless channel B is such that the mobile station 10 cannot discriminate, that is, the interval in which the mobile station 10 must communicate in the low-speed communication mode. As a result, it is assumed that the transmission capability of the mobile station 10 when the wireless channel B is used is 9.6 k / bps.
Then, it is assumed that both radio channel A and radio channel B can be simultaneously used by up to 300 mobile stations 10 by time division multiplexing.
[0037]
FIG. 5 is a flowchart showing the operation of the control station 12 when establishing a wireless channel between the mobile station 10 and the base station 11.
First, upon detecting a signal requesting the start of data communication from the mobile station 10 (step S100), the monitoring control unit 124 of the control station 12 performs authentication processing of the mobile station 10 (step S101). When the authentication is established (Yes in step S101), the control station 12 shifts the processing to step S102, and starts an operation of determining a radio channel to be allocated to the mobile station 10.
[0038]
The control station 12 allocates the wireless channel A to the mobile station 10 when the number a of the mobile stations 10 communicating with the established wireless channel A is equal to or less than the variable δ (Yes in step S102) (step S102). Step S103). As a result, when the wireless channel A is established between the mobile station 10 and the base station 11, the mobile station 10 performs data transmission and reception by simultaneously using the uplink channel and the downlink channel of the wireless channel A, and performs high-speed communication. be able to.
[0039]
FIG. 6 is a conceptual diagram showing a state where the relationship represented by a <δ is satisfied. Since the total number of mobile stations 10 that can simultaneously use the wireless channel A is 300 and the same applies to the wireless channel B, δ = (t_a-T_b) N / t_aIt will be $ 200 (unit). Therefore, as shown in FIG. 6, when the total number of mobile stations 10 simultaneously using wireless channel A is less than 200, control station 12 establishes wireless channel A with base station 11. Until the number of mobile stations 10 to be reached reaches 200, the wireless channel A is allocated to the mobile stations 10 that newly request data communication.
[0040]
Eventually, it is assumed that the number of mobile stations 10 simultaneously establishing the radio channel A with the base station 11 reaches 200. FIG. 7 is a conceptual diagram illustrating a state where a = δ. From this state, it is possible to further allocate the wireless channel A to the mobile station 10. However, in this case, the number of the mobile stations 10 using the wireless channel A becomes too large even though the wireless channel B is vacant. As a result, the communication efficiency of the entire mobile communication system 1 decreases. Therefore, the radio channel B is assigned to the mobile station 10 in addition to the radio channel A.
[0041]
The control station 12 that has detected that the wireless channel A has reached the state shown in FIG. 7 (No in step S102) moves the process to step S104, and sends a request to the mobile station 10 that newly requests wireless channel allocation. It is determined whether or not the wireless channel B should be allocated (step S104). Here, the transmission capacity of the wireless channel B isWireless channel AIs 1/3 of the transmission capacity of Therefore, when the control station 12 establishes a new wireless channel with the mobile station 10, the ratio between the wireless channel A and the wireless channel B becomes higher.1: 3The base station 11 is controlled so that
[0042]
FIG. 8 is a conceptual diagram showing a state where the number a of the mobile stations 10 establishing the wireless channel A is a> δ. Here, the ratio of the number a of the mobile stations 10 establishing the radio channel A to the number b of the mobile stations 10 establishing the radio channel B is1: 3The control station 12 newly establishes a radio link while the number b of the mobile stations 10 establishing the radio channel B with the base station 11 is less than 3 (a−δ) (Yes in step S104). The wireless channel B is allocated to the mobile station 10 which requests the establishment of the channel (step S105).
[0043]
Then, when the number of mobile stations 10 establishing the wireless channel continues to increase and the number b of mobile stations 10 establishing the wireless channel B becomes 3 (a−δ) or more (No in step S104), the control station 12 Allocates the wireless channel A to the mobile station 10 that newly requests the start of data communication. By controlling in this way, even when the wireless zone 110 is congested, it is possible to maintain the efficiency of data communication and to allocate a wireless channel capable of communicating as fast as possible to the mobile station 10.
[0044]
<3. Effects of Embodiment>
As described above, in the mobile communication system 1 of the present embodiment, the wireless channels are not allocated so that the number of mobile stations 10 communicating with each wireless channel is averaged. A radio channel is allocated to the mobile station 10 on the basis of a throughput based on a frequency interval between an uplink channel and a downlink channel. Therefore, the possibility that the mobile station 10 can communicate in the high-speed communication mode is increased. Then, following the improvement of the communication efficiency of the mobile station 10, the communication efficiency of the mobile communication system 1 also improves.
[0045]
<Modification>
The method of allocating radio channels to control stations and mobile stations according to the present invention is not limited to the above-described embodiment, and various changes can be made within the technical idea of the present invention. .
[0046]
(1) In the above embodiment, the throughput is calculated based on the number of mobile stations using the wireless channel, and based on the calculation result, the mobile station that newly requests the allocation of the wireless channel is assigned to which wireless channel. The description has been made in the mode of determining whether or not. However, the calculation of the throughput of the wireless channel need not be based on the number of mobile stations. For example, the calculation of the throughput of the wireless channel may be based on the usage rate of the wireless channel. Hereinafter, the principle of the present modification will be described using the radio channels C and D as an example.
[0047]
First, assuming that the traffic of the wireless channel conforms to the M / M / 1 model, the normalized average waiting time of the wireless channel is represented by the following equation (5).
(Equation 5)

(However, ρ = wireless channel usage rate)
[0048]
Then, the normalized average throughput T in the case of the radio channel usage rate ρ_hIs represented by the following equation (6).
(Equation 6)

[0049]
And the transmission capacity of the wireless channelt _c Then, the throughput T of the wireless channel C_cIs represented by the following equation (7).
(Equation 7)

[0050]
As described above, the transmission capacity of the radio channel D is t_dThen, the throughput T of the wireless channel D_dIs represented by the following equation (8). Where t_c> T_dAnd
(Equation 8)

[0051]
Here, in the data communication of the mobile station 10, the switching between the high-speed communication mode and the low-speed communication mode is performed by T_c= T_dThat is, the condition is satisfied. Therefore, from the above equations (7) and (8), the switching point of the communication mode is t_c(1-ρ_c) = T_d(1-ρ_d), Which is transformed to obtain the following equation (9).
(Equation 9)

[0052]
From equation (9), the usage rate ρ of the wireless channel C_cIs (t_c-T_d) / T_cIt can be understood that the control unit 12 may allocate the radio channel C to the mobile station 10 until the number of mobile stations 10 is reached. In this case, the mobile station 10 can always perform communication in the high-speed communication mode.
[0053]
Also, the usage rate ρ of the radio channel C_cIs t_c-T_dIn the case where the value exceeds the value represented by_cAnd transmission capacity t of radio channel D_dAnd t_c: T_dA wireless channel is assigned to the mobile station 10 such that By doing so, a radio channel can be assigned to the mobile station 10 according to the transmission capacity of the radio channel C and the transmission capacity of the radio channel D, and a radio channel that must communicate in the low-speed communication mode is assigned to the mobile station 10. Can be minimized.
[0054]
In the mobile station 10, t_c: T_dAssigning a wireless channel at the ratio of means that a wireless channel is assigned to the mobile station 10 so as to satisfy the relationship shown in the following equation (10).
(Equation 10)

(However, γ = (t_c-T_d) / T_c)
[0055]
It is also possible to control the wireless channel assignment to the mobile station 10 according to the above principle. Therefore, as a program stored in the ROM 121 of the control station 12, a program describing a procedure for calculating a wireless channel throughput based on the above-described principle is stored, and the procedure described in this program may be executed by the CPU 120. Good. In short, any mode may be used as long as the control station 12 calculates the radio channel throughput and allocates the radio channel to the mobile station 10 based on the calculation result.
[0056]
(2) In the above-described embodiment, the mobile station adopting the PDC scheme has been described as an example. However, the mobile station does not necessarily need to adopt the PDC scheme. For example, a GSM (Global System for Mobile communication) system may be adopted, or a PHS (Personal Handyphone System) may be used. In short, when establishing a radio channel with a base station, there is a frequency difference between the uplink channel and the downlink channel, and any system that changes the communication speed of the mobile station according to the frequency difference is used. However, it is possible to apply the present invention.
[0057]
【The invention's effect】
As described above, in the wireless communication control device and the wireless channel assignment method of the present invention, the assignment of the wireless channel to the mobile station is performed based on the throughput of each wireless channel. Available wireless channels.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a mobile communication system 1.
FIG. 2 is a conceptual diagram showing a communication state of a mobile station 10 in a high-speed communication mode.
FIG. 3 is a conceptual diagram showing a communication state of a mobile station 10 in a low-speed communication mode.
FIG. 4 is a block diagram showing an electrical configuration of the control station 12.
FIG. 5 is a flowchart showing an operation of selecting a frequency of a channel established between the mobile station 10 and the base station 11.
FIG. 6 is a conceptual diagram showing a state where a relationship represented by a <δ is satisfied.
FIG. 7 is a conceptual diagram showing a state where a = δ.
FIG. 8 is a conceptual diagram showing a state where a relationship represented by a> δ is satisfied.
[Explanation of symbols]
10 mobile station, 11 base station, 12 control station, 120 CPU, 124 monitoring control unit.

Claims (5)

Throughput calculation means for calculating the throughput of the wireless channel based on the transmission capacity of the mobile station and the channel usage rate,
When the throughputs of the first wireless channel and the second wireless channel having a lower transmission capacity of the mobile station than the first wireless channel are equal to each other when the throughputs of the first wireless channel and the second wireless channel are equal to each other. Calculating means for calculating a channel usage rate of the first wireless channel;
For a mobile station newly requesting the allocation of a radio channel, the first radio channel is allocated to the mobile station until the channel usage rate calculated by the calculation means is reached, and the first radio channel and the After the point in time when the throughput of the second radio channel becomes equal, each time a mobile station requesting a new radio channel allocation appears, the radio channel having the higher throughput among the first radio channel and the second radio channel And a allocating means for allocating to the mobile station . . 2. The wireless communication control according to claim 1, further comprising: means for obtaining the channel usage rate based on mobile stations using the wireless channel and the maximum number of mobile stations to which the wireless channel can be assigned. apparatus. A first step of calculating a wireless channel throughput based on the transmission capacity of the mobile station and the channel usage rate;
When the throughputs of the first wireless channel and the second wireless channel having a lower transmission capacity of the mobile station than the first wireless channel are equal to each other when the throughputs of the first wireless channel and the second wireless channel are equal to each other. A second step of determining a channel usage rate of the first wireless channel;
Assigning the first wireless channel to the mobile station until the channel usage rate determined in the second step is reached for the mobile station newly requesting the assignment of the wireless channel; After the point in time when the throughput of the second wireless channel becomes equal to that of the second wireless channel, the higher the throughput of the first wireless channel and the throughput of the second wireless channel each time a new mobile station that requests allocation of a wireless channel appears. Allocating a radio channel to the mobile station . On the computer,
A throughput calculation function for calculating the throughput of the wireless channel based on the transmission capacity of the mobile station and the channel usage rate,
When the throughputs of the first wireless channel and the second wireless channel having a lower transmission capacity of the mobile station than the first wireless channel are equal to each other when the throughputs of the first wireless channel and the second wireless channel are equal to each other. A calculation function for calculating a channel usage rate of the first wireless channel;
For a mobile station newly requesting the allocation of a radio channel, the first radio channel is allocated to the mobile station until the channel usage rate calculated by the calculation means is reached, and the first radio channel and the After the point in time when the throughput of the second radio channel becomes equal, each time a mobile station requesting a new radio channel allocation appears, the radio channel having the higher throughput among the first radio channel and the second radio channel And a program for realizing an assignment function of allocating to the mobile station . A computer-readable recording medium on which the program according to claim 4 is recorded.

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