JP2004194166A - Transmission power control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission power control system capable of reducing a transmission power in the communication between a base station and a mobile station by using a CDMA system . <P>SOLUTION: When there is no data from the mobile station 10 to the base station 20, the mobile station 10 stops transmission of an incoming individual channel, starts an incoming common channel or the incoming common channel and an outgoing common channel, and uses the incoming common channel to transmit outgoing transmission power control information. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transmission power control system, and more particularly to a transmission power control system that controls the outer loop downlink transmission power of a CDMA (Code Division Multi Access) type cellular telephone device.
[0002]
[Prior art]
In a cellular phone (cellular phone) or the like, communication is performed by employing a CDMA communication method. That is, a plurality of communications are performed simultaneously using signals in the same frequency band by the spread spectrum technique. In spread spectrum, an audio signal digitally encoded on the transmission side is subjected to arithmetic processing with high-speed data called a pseudo-noise code (PN code), converted into a signal with a wide frequency spectrum, and transmitted. On the receiving side, the original audio signal is restored using the same PN code. The CDMA system has a dedicated channel for transmitting data and a common channel for transmitting control information including transmission power control.
[0003]
In such CDMA communication, each mobile station (or mobile terminal) communicates with a base station in a service area where the mobile station exists (or is used). In order to obtain desired communication quality between the base station and the mobile station, it is necessary to control the transmission power of the base station. Therefore, during communication using the dedicated channel, a TPC (Transmit Power Control: transmission power control) bit of the uplink dedicated channel is inserted to control the transmission power of the downlink dedicated channel. Conventional techniques related to such transmission power control techniques are disclosed in various documents (for example, see Patent Documents 1 and 2). In particular, the former performs communication using a common channel and an individual channel between a mobile radio and a radio base station, and during this communication, communication traffic in the mobile radio is shifting from a sparse state to a honey state. At this time, a traffic control method for mobile data communication in which a radio base station or a mobile radio device makes a transition determination from a common channel to an individual channel is disclosed. The latter is a code division multiple access communication system that measures a reception level of a reception signal of a transmission signal from a mobile terminal, creates a transmission power control signal for each channel, and transmits the transmission power control signal to each mobile terminal using a downlink common channel. Has been disclosed.
[0004]
Next, a typical conventional transmission power control technique will be briefly described. In FIG. 6, (a) shows an uplink (from the mobile station to the base station) individual channel, and (b) shows a downlink (from the base station to the mobile station) individual channel. As is clear from FIG. 6A, the TPC bit occupies only a small part of one slot.
[0005]
When the mobile station activates the dedicated channel, the mobile station performs downlink transmission power control using the above-described TPC bit of the uplink dedicated channel. That is, as shown in FIGS. 5 (a) and 5 (b), the downlink transmission power control is performed for each slot according to the TPC bit of the uplink dedicated channel. Will change sequentially. In other words, when the communication state (or communication quality) is good, the transmission power is reduced (to avoid unnecessary power consumption), and when the communication state is bad, the transmission power is increased and the predetermined communication is performed. Maintain quality.
[0006]
[Patent Document 1]
Re-publication WO00 / 35235 (pages 11-12, Fig. 3)
[Patent Document 2]
JP-A-2000-78078 (pages 4-6, FIG. 3)
[0007]
[Problems to be solved by the invention]
However, in the above-described conventional technology, it is difficult to reduce power consumption during communication. The reason is that even when there is no uplink data or the data amount is small, it is necessary to transmit the uplink dedicated channel for downlink transmission power control and the base station needs to synchronize with the uplink dedicated channel. This is because it must be transmitted at an appropriate interval.
[0008]
[Object of the invention]
The present invention has been made in view of the above-described problems of the related art, and has as its object to provide a transmission power control system capable of reducing transmission power during communication.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the transmission power control system of the present invention employs the following characteristic configuration.
[0010]
(1) In a transmission power control system when a mobile station communicates in a CDMA system having a dedicated channel for communication and a common channel for control signals via a plurality of base stations each having a unique service area,
A transmission power control system that transmits information for downlink transmission power control using an uplink common channel when the bit rate of uplink data is low.
[0011]
(2) The transmission power control system according to (1), wherein the case where the data has a low bit rate means that there is no data, and the mobile station stops transmission of the uplink dedicated channel.
[0012]
(3) In a transmission power control system when a mobile station communicates via a base station in a CDMA system having a dedicated channel for communication and a common channel for control signals,
When there is no uplink data, the mobile station stops transmission of the uplink dedicated channel, activates a common channel, and transmits a TPC bit.
[0013]
(4) The mobile station transmits a preamble part before transmitting the TPC bit, and the base station, which has received the preamble part via a common channel, inserts an Acknowledge bit into a downlink dedicated channel to perform downlink transmission power control. The transmission power control system according to (3), which responds to the change.
[0014]
(5) The mobile station receiving the Acknowledge bit activates an uplink common channel, inserts and transmits a TPC bit, and the base station that receives the TPC bit controls downlink transmission power (4). Transmission power control system.
[0015]
(6) The transmission power control system according to (4), wherein the mobile station that has received the Acknowledge bit activates the uplink and downlink common channels.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the configuration and operation of a preferred embodiment of a transmission power control system according to the present invention will be described in detail with reference to the accompanying drawings.
[0017]
First, FIG. 1 is a block diagram showing a configuration of a mobile station of a first embodiment of the transmission power control system according to the present invention. The mobile station 10, which is a CDMA cellular telephone device, includes an antenna 11, a radio unit 12, a baseband unit 13, a processor unit 14, a memory (storage unit) 15, and a storage medium 16.
[0018]
Next, the main functions or operations of the components 11 to 16 of the moving pole 10 described above will be described. The wireless unit 12 modulates and demodulates a wireless signal transmitted and received via the antenna 11. The baseband unit 13 is a part that performs error correction encoding, division into radio frames, and orthogonal code spreading on transmission data passed from the processor 14. Further, the received data demodulated by the radio unit 12 is subjected to orthogonal code despreading, power measurement, connection of radio frames, and error correction decoding. Then, the result of the power measurement of the received data is compared with the target received power, a transmission power control bit for performing base station transmission power control is created, and mapped to a physical channel and transmitted. I do. The processor unit 14 extracts the program from the storage medium 16 and executes the program. The memory 15 stores (stores) information from the processor unit 14. The storage medium 16 stores a program executed by the processor unit 14.
[0019]
Next, the overall operation including the mobile station 10 and the base station 20 shown in FIG. 1 will be described with reference to the sequence diagram of FIG. 2 and the timing chart of FIG. In FIG. 3, (a) shows the uplink dedicated channel, (b) shows the uplink common channel, and (c) shows the transmission or reception power of the downlink dedicated channel. When the processor unit 14 of the mobile station 10 performing communication using the dedicated channel determines that there is no uplink data or that the bit rate of the uplink data is low, the processor unit 14 sends a layer 2 message to the base station 20. To transmit a downlink transmission power control change request signaling.
[0020]
The processor unit 14 requests the baseband unit 13 to transmit a downlink transmission power control change request (step S21). The baseband unit 13 that has received the signaling transmission request transmits the signaling using the radio unit 12. Radio section 12 transmits signaling using antenna section 11. The base station 20 that has received the downlink transmission power control change request signaling transmits the downlink transmission power control change response signaling to the mobile station 20 (step S22).
[0021]
The processor unit 14 that has received the signaling of the downlink transmission power control change response (step S22) instructs the baseband unit 13 to change the downlink transmission power control. The baseband unit 13 that has received the instruction to change the downlink transmission power control activates the uplink common channel (step S23).
[0022]
The baseband unit 13 determines a target reception level from the block error rate (error rate) of the downlink dedicated channel, and creates transmission power control information (TPC bit) such that the reception level of the downlink dedicated channel becomes the target reception level. . The baseband unit 13 transmits the TPC bit on the uplink common channel. The baseband unit 13 transmits the preamble part on the uplink common channel. The base station 20 that has received the preamble part creates an Acknowledge bit, maps it to a downlink dedicated channel, and transmits it. Upon receiving the Acknowledge bit, the baseband unit 13 maps the TPC bit to the message part of the uplink common channel and transmits it. The base station 20 that has received the TPC bit on the uplink common channel adjusts (or controls) the transmission power of the downlink dedicated channel.
[0023]
As described above, when there is no uplink data (or when the data rate is low), this is detected by a known means, and the mobile station 10 stops transmission of the uplink dedicated channel and activates the uplink common channel. Then, the preamble part is transmitted to transmit the TPC bit (step S31). The base station 20 that has received the preamble part of the common channel inserts an Acknowledge bit into the downlink dedicated channel and notifies the mobile station 10 that the reception of the preamble part is OK (step S32). The mobile station 10 receiving the Acknowledge bit inserts the TPC bit into the message part of the uplink common channel and transmits the message (step S33). The base station 20 receiving this message part adjusts (or controls) the downlink transmission power using the TPC bit. Since the minimum transmission interval of the message part of the uplink common channel is longer than that of the individual channel that needs to transmit the TPC bit for each slot, the transmission frequency is reduced, and the power consumption can be reduced.
[0024]
Next, a second embodiment of the transmission power control system according to the present invention will be described in detail. In the second embodiment, the basic configuration of the mobile station is the same as that of FIG. In the above-described first embodiment, the downlink dedicated channel is used for transmitting the Acknowledge bit for confirming the reception of the preamble part of the uplink common channel. In the second embodiment, the Acknowledge bit is transmitted on the downlink common channel. Things.
[0025]
Next, an overall operation of the second embodiment will be described with reference to FIG. 1, FIG. 4 and FIG. FIG. 4 is a sequence diagram, and FIG. 5 is a timing chart. In FIG. 5, (a) shows the operation of the uplink dedicated channel, (b) shows the operation of the downlink common channel, (c) shows the operation of the downlink dedicated channel, and (d) shows the operation of the downlink common channel.
[0026]
When the processor unit 14 of the mobile station 10 performing communication using the dedicated channel determines that there is no uplink data or the bit rate of the uplink data is low, the processor unit 14 sends a layer 2 message to the base station. The signaling of the downlink transmission power control change request is transmitted.
[0027]
The processor unit 14 requests the baseband unit 13 to transmit a downlink transmission power control change request (step S41). The baseband unit 13 that has received the signaling transmission request transmits the signaling using the radio unit 12. Radio section 12 transmits signaling using antenna section 11. The base station 20 that has received the signaling of the downlink transmission power control change request described above transmits signaling of the downlink transmission power control change response to the mobile station (step S42).
[0028]
Next, the processor unit 14 that has received the signaling of the downlink transmission power control change response described above instructs the baseband unit 13 to change the downlink transmission power control. The baseband unit 13 that has received the instruction to change the downlink transmission power control activates the uplink common channel and the downlink common channel (step S43). The baseband unit 13 determines a target reception level based on the block error rate of the downlink dedicated channel, and creates transmission power control information (TPC bit) such that the reception level of the downlink dedicated channel becomes the target reception level. The baseband unit 13 transmits the TPC bit on the uplink common channel (step S51 in FIG. 5).
[0029]
The baseband unit 13 transmits the preamble part on the uplink common channel. The base station 20 that has received the preamble part creates an Acknowledge bit, maps it to a downlink common channel, and transmits it. Upon receiving the Acknowledge bit, the baseband unit 13 maps the TPC bit to the message part of the uplink common channel and transmits it (step S52 in FIG. 5). The base station 20, which has received the TPC bit on the uplink common channel, adjusts (or controls) the transmission power of the downlink dedicated channel (step S53 in FIG. 5). According to the above-described procedure, downlink transmission power control is performed.
[0030]
The configuration and operation of the preferred embodiment of the transmission output control system according to the present invention have been described above in detail. However, it should be noted that such embodiments are merely examples of the present invention and do not limit the present invention in any way.
[0031]
【The invention's effect】
As apparent from the above description, according to the transmission power control system of the present invention, the following remarkable practical effects can be obtained. That is, power consumption can be significantly reduced during communication of the individual channel. The reason is that information for performing downlink dedicated channel transmission power control is transmitted using the uplink common channel, so that the base station does not need to synchronize with the uplink dedicated channel from the mobile station, and This is because it is possible to lengthen the uplink transmission interval.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a mobile station in a transmission power control system of the present invention.
FIG. 2 is a sequence diagram illustrating an operation of the first embodiment of the transmission power control system of the present invention.
FIG. 3 is a timing chart illustrating an operation of the first embodiment of the transmission power control system of the present invention.
FIG. 4 is a sequence diagram illustrating an operation of the second embodiment of the transmission power control system of the present invention.
FIG. 5 is a timing chart illustrating the operation of the second embodiment of the transmission power control system of the present invention.
FIG. 6 is an explanatory diagram of an operation of a conventional typical transmission power control system.
[Explanation of symbols]
10 mobile stations (mobile terminals)
DESCRIPTION OF SYMBOLS 11 Antenna part 12 Radio part 13 Baseband part 14 Processor part 15 Memory 16 Recording medium 20 Base station

Claims (6)

In a transmission power control system when a mobile station communicates in a CDMA system having a dedicated channel for communication and a common channel for control signals via a plurality of base stations each having a unique service area,
A transmission power control system characterized by transmitting information for downlink transmission power control using an uplink common channel when the bit rate of uplink data is low. The transmission power control system according to claim 1, wherein when the bit rate of the data is low, there is no data, and the mobile station stops transmission of an uplink dedicated channel. In a transmission power control system when a mobile station communicates via a base station in a CDMA system having a dedicated channel for communication and a common channel for control signals,
When there is no uplink data, the mobile station stops transmitting an uplink dedicated channel, activates a common channel, and transmits a TPC bit. The mobile station transmits a preamble part before transmitting the TPC bit, and the base station, which has received the preamble part via a common channel, inserts an Acknowledge bit into a downlink dedicated channel and responds with a downlink transmission power control change response. The transmission power control system according to claim 3, wherein: The mobile station receiving the Acknowledge bit activates an uplink common channel, inserts and transmits a TPC bit, and the base station that receives the TPC bit controls downlink transmission power. 5. The transmission power control system according to 4. The transmission power control system according to claim 4, wherein the mobile station that has received the Acknowledge bit activates the uplink and downlink common channels.

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