JPH10164648A - Transmission power controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress reduction in the efficiency of frequency and slot caused by disability in the use of idle slot at the same frequency at another base station by transmitting this idle slot with maximum transmission power concerning a transmission power controller equipped with a time division multiplexing means, channel assign control means and transmitting means. SOLUTION: A base station controller 11 of a mobile communication system 10 is connected through a signal line 23 to plural base stations 12 and provided with a transmission power controller 1 inside. This transmission power controller 1 is provided with a TDMA part to become the time division multiplexing means, dynamic channel assign part having functions as channel assign control means and idle slot specifying means, and transmission control part having functions as transmitting means and transmission control means. The transmission control part transmits the transmission power of idle slot, which is turned to a non-used state by the channel assign part, with maximum transmission power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to transmission power control in a mobile communication system using a Time Division Multiple Access (TDMA) system.

[0002]

2. Description of the Related Art Conventionally, for example, a digital telephone network or an integrated service digital network (hereinafter referred to as ISDN: Integrated S
In general, a transmission system in an ervices digital network) is configured by a multiplex transmission system using a TDMA system. In the TDMA system, a large amount of channel information is packed in one transmission path and transmitted by time-division multiplexing by shortening the pulse time width of information to be transmitted.

[0003] In a mobile communication terminal (hereinafter referred to as a mobile terminal) in a PDC (Personal Digital Cellular) system or the like employing a TDMA system in which three slots (or six slots) are multiplexed per carrier, each slot in a carrier is used. The frequency cannot be changed every time, and all the slots are configured to transmit at the same frequency. The used slot controls the transmission power in the range of 0 to -8 dB according to the distance from the base station. More specifically, when the distance between the base station and the mobile terminal is large, the mobile terminal performs transmission at the maximum transmission power (0 dB), and as the distance from the base station increases, at a step interval of 4 dB, -4 dB and -8 dB. The transmission power is reduced.

This prevents various adverse effects caused by an excessively high electric field strength when the transmission power is kept at the maximum transmission power despite the short distance between the base station and the mobile terminal. To do that. By the way, in actual transmission, not all slots in a carrier are always used for information transmission, and some slots are vacant at the time of information transmission (hereinafter, vacant slots). The empty slot is controlled to always transmit at -8 dB transmission power in order to perform diversity reception by antenna switching, which is general as a countermeasure for fading in the mobile terminal.

[0005]

SUMMARY OF THE INVENTION Such a conventional PD
The C system has been designed on the premise of a fixed allocation method based on a macro cell configuration having a cell radius of 1 km or more, so that it cannot cope with a recent rapid increase in the number of subscribers. Therefore, as a measure to cope with an increase in the number of subscribers in the future, a cell radius of 500 m
The following requirements such as microcelling and dynamic channel assignment are essential requirements.

[0006] This is because, when the cell radius is reduced to １ ／ or less by shifting the macro cell to the micro cell, the subscriber capacity can be increased four times or more to increase the capacity. This is because it is necessary to automatically perform frequency allocation by performing dynamic channel allocation. However, when performing dynamic channel allocation in the above-described PDC system, the following problems occur.

That is, as shown in FIG. 4, when base station A and base station B by three-slot multiplexing are located adjacent to each other, base station A uses only the second slot of frequency f1, , If the third slot is not used, as described above,
The third slot is -8 dB for diversity reception
Since the transmission power is controlled by the transmission power, the transmission signal acts as an interference wave on the adjacent base station B, so that the base station B cannot use the first and third slots at the frequency f1. As a result, there is a problem that the frequency use efficiency is reduced.

Further, as shown in FIG. 5, when a base station C and a base station D by three-slot multiplexing are located at a certain distance from each other, if dynamic channel allocation is performed by the TDMA method, the channel allocation is normally performed. Since this is performed on a slot basis, the base station C can use the first slot with the carrier a of the frequency f1, and the base station D can use the third slot with the carrier b of the frequency f1. However, since all the slots in the carrier have the same frequency, the third slot cannot be used in the base station C and the first slot cannot be used in the base station D, and the slot utilization efficiency is reduced. There is.

[0009] It is an object of the present invention to provide a transmission power control apparatus for preventing a decrease in frequency and slot utilization efficiency when performing dynamic channel allocation in order to solve the above problems.

[0010]

According to a first aspect of the present invention, there is provided a transmission power control apparatus for multiplexing data in a predetermined number of slots per carrier. Channel allocation control means for dynamically allocating a channel to a slot, and transmission means for transmitting the transmission power of an empty slot that has become unused by the allocation of the channel allocation control means at the maximum transmission power doing. In other words, the transmission power control apparatus of the present invention transmits an empty slot at the maximum transmission power, so that other base stations cannot use this empty slot at the same frequency, thus reducing the frequency and slot utilization efficiency. Can be suppressed.

According to a second aspect of the present invention, there is provided a transmission power control apparatus which performs time-division multiplexing with a predetermined number of slots per carrier, and dynamically multiplexes each slot multiplexed by the time-division multiplexing means. Channel allocation control means for performing efficient channel allocation, empty slot identification means for identifying unused slots which have become unused due to allocation by the channel allocation control means, and each slot multiplexed by the time division multiplexing means is preset. Transmission means for transmitting at the specified transmission power, and transmission control means for controlling the transmission means so that the transmission power of the vacant slot specified by the vacant slot specifying means is the maximum transmission power. I have. That is, the transmission power control device of the present invention transmits the empty slot specified by the empty slot specifying unit at the maximum transmission power, so that other base stations cannot use this empty slot at the same frequency, It is possible to suppress a decrease in frequency and slot utilization efficiency.

According to a third aspect of the present invention, the transmission means of the transmission power control apparatus is configured to transmit an empty slot at the maximum transmission power only when there is at least one transmission slot by the assignment of the channel allocation control means. . That is, when there is no transmission slot, the other base station can use the slot corresponding to the empty slot at the same frequency, so that it is possible to suppress a decrease in frequency and slot utilization efficiency.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on one illustrated embodiment. FIG. 1 is a diagram illustrating a main configuration of a transmission power control device according to the present embodiment, in which the transmission power control device 1 of the present invention is applied to a base station control device 11 in a mobile communication system 10. The mobile communication system 10 shown in FIG. 1 includes a base station controller 11, a plurality of base stations 12, a mobile communication switch 13, and a mobile station 14.

The base station controller 11 is connected to a plurality of base stations 12 via signal lines 23, and includes the transmission power controller 1 therein. As shown in FIG. 2, the transmission power control device 1 according to the present embodiment includes a TDMA unit 2 serving as a time division multiplexing unit, a dynamic channel assignment unit 3 having a function as a channel assignment control unit and an empty slot identification unit. , A transmission control unit 4 having a function as a transmission unit and a transmission control unit.

The TDMA unit 2 is provided with a time switch and a space switch (not shown) therein, and is a processing block for processing frame synchronization of data to be transmitted and data format of a slot. The dynamic channel assignment unit 3 dynamically and automatically assigns a frequency to each cell arrangement. This is because when a microcell is to be formed, the cell shape becomes a tree-like shape, and the cells are arranged so as to overlap each other under the influence of a complicated road shape, so that the frequency is manually assigned. This is because it requires a lot of effort and is not practical.

The transmission control unit 4 is for transferring data to be processed to the base station 12. In this case, for each slot, 0 dB, -4 dB,
Control is performed so that the transmission power is attenuated by any one of -8 dB. That is, when 0 dB is set as the attenuation rate, transmission control at the maximum transmission power is performed,
When -4 dB and -8 dB are set, transmission control with a transmission power less than half of the maximum transmission power is performed.

The base station 12 includes a plurality of transmitting / receiving units 1
5 for performing wireless communication with the mobile station 14. When data is transmitted from the transmission / reception unit 15, the transmission power of each slot is determined based on a control signal transferred from the transmission power control device 1 via the signal line 23, and is actually transmitted. Further, it sends the data received from the mobile station 14 to the base station controller 11 via the signal line 23. The mobile communication switch 13 is connected via a communication line 21 to another mobile communication system or an external network such as a fixed network.
The data from the external network is transferred to the base station controller 11 via the signal line 22 or the base station controller 11
2 is for transferring data input via the communication line 21 to an external network. The mobile station 14 is a station that can perform data communication with the nearest base station 12.

Next, an operation example of the transmission power control device 1 in the above-described embodiment will be described with reference to FIG. FIG. 3 is a diagram illustrating the concept of the transmission power control process according to the present embodiment. In the example shown in FIG. 3, for comparison, as in the conventional example shown in FIG. 5, the base station C ′ and the base station D ′ by three-slot multiplexing are located at a certain distance, and the TDM
It is assumed that dynamic channel allocation is performed by the A method.

In the mobile communication system using the TDMA system, since the frequency cannot be changed for each slot within a carrier, transmission and reception are performed at the same frequency for all slots as described above. Similarly, since channel allocation is normally performed in slot units, it is assumed that base station C 'uses only the first slot on carrier a of frequency f1.

In such a case, the transmission power control apparatus 1 of the present embodiment provides the transmission / reception unit 15 of the base station 12 with a minimum transmission for the remaining second and third slots. It instructs and controls transmission power control, that is, transmission with an attenuation rate of 0 dB. Thus, the second and third slots transmit at the maximum transmission power in the system. Then, in the base station D ′, the slot is not used because the interference wave from the base station C ′ is large, so the base station C ′ sets the third slot when receiving a call from another mobile station 14. Can be assigned, and slot utilization efficiency is improved.

In this case, if the same operation is performed on a vacant slot on a carrier that does not use any slot, there is a problem in operation of another base station 12, so that the number of transmission slots is one or more. Only in certain cases, empty slots are transmitted at the maximum transmission power.

Therefore, transmission of a vacant slot on a carrier using one or more slots has conventionally been a mere interference source. However, in this embodiment, a reserved slot is used because the vacant slot is used by its own station. And In addition, since the possibility of using an empty slot in the peripheral base station 12 is reduced, using the empty slot in the own station can increase the frequency use efficiency and the slot use efficiency.

As described above, in the present embodiment, an empty slot on a carrier that is using one or more slots performs transmission at the maximum transmission power. This makes it impossible for another base station located nearby to use the empty slot at the same frequency, so that it is possible to solve the problem of interference and the problem of reduced frequency and slot utilization efficiency.

[0024]

As is clear from the above description, according to the first and second aspects of the present invention, an empty slot is transmitted at the maximum transmission power, so that other base stations use the empty slot at the same frequency. Since it is no longer possible, it is possible to suppress a decrease in frequency and slot utilization efficiency.

According to the third aspect of the present invention, when there is no transmission slot, the other base stations use the same frequency,
Since a slot corresponding to this empty slot can be used, it is possible to suppress a decrease in frequency and slot utilization efficiency.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a transmission power control device according to an embodiment.

FIG. 2 is a schematic diagram illustrating a main configuration of a transmission power control device in FIG. 1;

FIG. 3 is a diagram illustrating a concept of transmission power control processing according to the present embodiment.

FIG. 4 is a diagram for explaining a problem with a conventional adjacent base station.

FIG. 5 is a diagram for explaining a problem with a conventional nearby base station.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 transmission power control device 2 TDMA unit (time division multiplexing unit) 3 dynamic channel allocating unit (channel allocation control unit, empty slot specifying unit) 4 transmission control unit (transmission unit, transmission control unit) 10 mobile communication system 11 base station Control device 12 Base station 13 Mobile communication switch 14 Mobile station 15 Transceiver unit 21 Communication line 22, 23 Signal line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04Q 7/10 H04Q 7/02 B 7/20

Claims (3)

[Claims] 1. A time-division multiplexing means for multiplexing a predetermined number of slots per carrier, and a channel allocation control for dynamically allocating channels to each of the slots multiplexed by the time-division multiplexing means. Transmission power control apparatus comprising: transmission means for transmitting, at maximum transmission power, transmission power of a vacant slot which has become unused due to allocation by the channel allocation control means. 2. Time-division multiplexing means for multiplexing a predetermined number of slots per carrier, and channel allocation control for dynamically allocating channels to each of the slots multiplexed by said time-division multiplexing means. Means, an empty slot identifying means for identifying an empty slot which has become unused due to the allocation of the channel allocation control means, and transmitting each slot multiplexed by the time division multiplexing means at a preset transmission power. Transmission means for controlling the transmission means so that the transmission power of the vacant slot specified by the vacant slot specifying means becomes the maximum transmission power. . 3. The transmission unit according to claim 1, wherein the transmission unit transmits an empty slot at a maximum transmission power only when there is at least one transmission slot, by the allocation of the channel allocation control unit. Transmission power control device.