Portable terminal set and control method thereof

Monitoring is made as to whether the serial number of header incorporated to the data sent to a Radio Link Control (RLC) after a decoding process is continuous. When it is determined as a result of monitoring for a predetermined period of time that no defect is present in the header numbers, a multi-path timing is detected by taking a correlation between the result of the detection and spread codes of received signals and a pilot signal. From this multi-path timing, a station, from which data are to be received in fingers, is determined for interrupting processes of de-spread, RAKE reception and decoding, thus reducing power consumed in the processes.

BACKGROUND OF THE INVENTION

This application claims benefit of Japanese Patent Application No. 2004-267556 filed on Sep. 14, 2004, the contents of which are incorporated by the reference.

The present invention relates to portable terminal set and portable terminal control method capable of suitably receiving data of a service for broadcasting data of a large volume of contents including video and images to a plurality of portable terminal sets.

As a mobile communication system, a service is provided, which broadcasts data of a large volume of the same contents including voice and images to a plurality of portable terminal sets. This system is called MBMS (Multimedia Broadcast Multicast System).

In MBMS of broadcast type, a number of portable terminals receive a common channel (hereinafter referred to a common channel). Therefore, it is impossible to control power of the common channel based on the receiving quality of each portable terminal. This means that it is impossible to control the receiving operation for each data broadcast via the common channel. For example, in the neighborhood of the boundary between the coverage areas of base stations, in which the received signal quality is subject to deterioration, the portable terminal receives the same data from a plurality of base stations at different timings spaced apart by a predetermined time interval, decodes the signal from each base station, and selects data of good or better quality (this method being hereinafter referred to as selective combining method).

For example, even in the case of failure of normal reception and decoding of data transmitted from one base station, if data transmitted from a different base station later could be normally received and decoded, it is possible to select the defect-free data. It is thus possible to improve the received signal quality in the base station coverage area boundary neighborhood.

Literate 1 (Japanese Patent Laid-open 2000-115070) proposes a one-time broadcast system, in which at the time of one-time broadcast one-time broadcast discrimination data for discriminating the one-time broadcast is transmitted to and stored in the receiving set side, at the time of one-time broadcast start the receiving set receives one-time broadcast data discrimination data from a relay means, compares the received data with already stored one-time broadcast discrimination data and, when the two data are identical, limits the reception. The system thus can present reception of the same one-time data in the receiving set a plurality of times.

Literature 2 (Japanese Patent Laid-open 2001-103529) proposes a communication terminal set, in which at the time of soft hand-over for communication with a plurality of base stations the quality of down line signals from the plurality of base stations is checked, and a base station of good down line signal quality is selected to be the next transmitting station in selective synthesis unit. It is thus possible to obtain high quality reception.

Literature 3 (Japanese Patent Laid-open Hei 11-284635) proposes an ATM cell transfer control method and transfer control system, which is effective in the case of burst cell defect generation during data transfer with AAL5 due to failure in a re-transfer process in a layer upper than a CPCS layer of the AAL 5 as a result of transfer quality deterioration or reception level deterioration caused by fading in a wireless transmission section. In such case, introduction of unnecessary traffic in a subsequent stage ATM backbone network can be prevented by stopping the transmission of cell data subsequent to the defect cell providing cell number data of cells before the defect cell to cell data. Besides, the unnecessary traffic part can be made charge-free in the ATM backbone network to improve the efficiency in use of the ATM backbone network.

The above prior art inventions, however, have the following problems.

The selective combining method for data broadcast by MBMS, even when earlier data transmitted from a certain base station has been suitably received and decoded, the same data later transmitted from a different base station is received and decoded, and RLC (Radio Link Control) as an upper rank layer checks whether the same data is already present and discards data determined to be the same. Therefore, consequently data receiving/decoding process on the same data is executed a plurality of times.

According to the invention disclosed in Literature 1, at the time of the one-time broadcast start the one-time broadcast discrimination data is received from the relay means and compared with the already stored one-time broadcast discrimination data, and when the two compared data are identical, the reception is limited, thereby preventing the reception of the same one-time broadcast by the receiving set a plurality of times. However, irrespective of whether the data transmitted earlier has been normally received, the reception of the data transmitted later is rejected. Therefore, data quality reduction is liable.

According to the invention disclosed in Literature 2, at the time of soft hand-over for communication with a plurality of base stations, the quality of the down-line signals from the plurality of base stations is checked, and a base station with good down-line signal quality is selected to be the next transmitting station in the selective synthesis unit. It is thus possible to receive good quality line signals. However, receiving/decoding process is executed on the same data a plurality of times.

According to the invention disclosed in Literature 3, in the case of detection of a defect in the received data, the reception of data subsequent to the defect detection is stopped, thus preventing unnecessary data reception and improving the network use efficiency. However, it is impossible to receive normal data.

SUMMARY OF THE INVENTION

The present invention has an object of providing portable terminal set and portable terminal control method, in which at the time of normal reception of certain data, receiving/decoding process on the same data broadcast later from a different base station is stopped, thus reducing power consumed in the data receiving/decoding process.

According to an aspect of the present invention, there is provided a portable terminal set comprising a receiving means for receiving data from a plurality of base stations, an de-spreading means for de-spreading the data received by the receiving means, a combining means for combining the same data from the base stations de-spread in the de-spreading means, a decoding means for decoding the data combined in the combining means, a selectively combining means for selectively combining the decoded data from the decoding means, a detecting means for detecting any defect in the selectively combined data from the selectively combining means, and a control means for controlling the operation of the entire portable terminal set, wherein: the portable terminal set further comprises: a first counting means for counting a time required for the processes in the de-spreading means, the combining means, the decoding means, the selectively combining means and the detecting means; an off-set time counting means for counting an off-set time from the start of data reception from a base station till the start of data reception from a different base station; and when the detecting means detects no defect in the data and also when the time counted in the first counting means is shorter than the off-set time, the control means interrupts the process in the de-spreading means, the combining means and the decoding means on the data from the different base station.

The portable terminal set further comprises a second counting means for counting a time required for the processes in the combining means, the decoding means, the detecting means and the selectively combining means; and when the detecting means detects no defect in the data and also when the time counted in the second counting means is shorter than the off-set time, the control means interrupts the processes in the combining means and the decoding means.

The portable terminal set further comprises a third counting means for counting a time required for the processes in the decoding means, the detecting means and the selectively combining means; and when the detecting means detects no defect in the data and also when the time counted in the third counting means is shorter than the off-set time, the control means interrupts the process in the decoding means.

The data incorporate sequence numbers indicative of their sequence and the detecting means detects a defect based on the sequence numbers. When the detecting means detects a defect in the data, the control means resumes the processes in all the means. The detecting means monitors for any defect for a predetermined period of time.

According to another aspect of the present invention, there is provided a control method of a portable terminal set including a receiving means for receiving data from a plurality of base stations, an de-spreading means for de-spreading the data received by the receiving means, a combining means for combining the same data from the base stations de-spread in the de-spreading means, a decoding means for decoding the data combined in the combining means, a selectively combining means for selectively combining the decoded data from the decoding means, a detecting means for detecting any defect in the selectively combined data from the selectively combining means, and a control means for controlling the operation of the entire portable terminal set, the method comprising steps of: a first counting step for counting a time required for the processes in the de-spreading means, the combining means, the decoding means, the selectively combining means and the detecting means; an off-set time counting step for counting an off-set time from the start of data reception from a base station till the start of data reception from a different base station; and interrupting step for interrupting the process in the de-spreading means, the combining means and the decoding means on the data from the different base station when the detecting means detects no defect in the data and also when the time counted in the first counting means is shorter than the off-set time.

The method further comprises a second counting step for counting a time required for the processes in the combining step, the decoding step, the detecting step and the selectively combining step; and interrupting step for interrupting the processes in the combining step and the decoding step when the detecting means detects no defect in the data and also when the time step in the second counting means is shorter than the off-set time.

The method further comprises a third counting step for counting a time required for the processes in the decoding step, the detecting means and the selectively combining step; and an interrupting step for interrupting the process in the decoding step when the detecting step detects no defect in the data and also when the time counted in the third counting step is shorter than the off-set time. The data incorporate sequence numbers indicative of their sequence and the detecting step detects a defect based on the sequence numbers. When the detecting step detects a defect in the data, the control step resumes the processes in all the steps. The detecting step monitors for any defect for a predetermined period of time.

According to further aspect of the present invention, there is provided a control method of a portable terminal set which receives data from a plurality of base stations, de-spreading the data received, combining the same data from the base stations de-spread in the de-spreading means, decoding the combined data, selectively combining the decoded data, detecting any defect in the selectively combined data, the method comprising steps of counting a first time required for the processes in the de-spreading, the combining, the decoding, the selectively combining and the detecting; counting an off-set time from the start of data reception from a base station till the start of data reception from a different base station; and interrupting the process in the de-spreading, the combining and the decoding on the data from the different base station when any defect is not detected in the data and also when the first time is shorter than the off-set time.

According to the present invention, monitoring is made as to whether header numbers incorporated in the data transmitted to the RLC after the a decoding process are continuous to detect presence of no header number defect as a result of monitoring for a predetermined period of time. A correlation between the detected result and spread codes of received signals and a pilot signal is taken to detect a multi-path timing. From the detected multi-path timing, a base station is determined, in which data are received in fingers. With this means, when the signals transmitted from a certain base station and in selective combining reception is good and are free from any data defect, de-spread, RAKE reception and decoding on data transmitted from any different base station can be interrupted, thus reducing power required for the processes.

With this means, the de-spread, RAKE reception and decoding on data transmitted from any different base station can be interrupted, thus reducing power required for the processes.

Other objects and features will be clarified from the following description with reference to attached drawings.

PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1is a block diagram showing the circuit arrangement of an embodiment of the portable terminal set capable of receiving data from a broadcast service system according to the present invention.

A portable telephone set according to the present invention comprises a plurality of fingers11ato11n(collectively referred to as11), a selector12, RAKE adders13aand13b, decoders14aand14b, an RCL15, a detector16, a reception controller17and a path searcher18.

The fingers11are circuits for multiplying signals received from base stations21and22by spread code at a timing designated by the reception controller17, thereby obtaining a de-spread of the received signals (i.e., multi-path wave).

The selector12is a circuit for transmitting the inversely dispersed received signals obtained in the fingers11to the RAKE adders13aand13bwith spread code designated by the reception controller17and at a timing detected by the path searcher18.

In the wireless communication, a phenomenon of delayed reaching of radio waves reflected by buildings or the like on the earth occurs in addition to radio wave directly reaching from the transmitting side to the receiving side. Interference of the delayed waves causes communication quality reduction. For improving the communication quality, the RAKE adders13aand13bsynthesizes a plurality of inversely dispersed received signals (i.e., multi-path wave) relevant to the multi-pathphenomenon. Specifically, the RAKE adders13aand13bare circuits for adding together the same data from the base stations as received from the individual fingers11via the selector12, such that the data are added together by in-phase addition at a matched timing. When the intensity of a certain received signal is reduced by the fading, the RAKE adders13aand13bcan restore the initial intensity with other delayed waves of higher intensities. Thus, it is possible to reduce the adverse effects of the fading.

The decoders14aand14bare circuits for decoding the in-phase addition data from the RAKE adders13aand13d.

The RLC15holds the decoded data from the decoders14aand14bfor a predetermined period of time, and executes a selective combining process on the data on the basis of header data incorporated in the data. For example, when a defect is present in the data received from the decoder14a, it is made up for with a corresponding part of the data received from the decoder14b. When the defect cannot be made up for with the data received from the decoder14b, the RLC15inputs the data to the detector16without making up for the defect. When no defect is present in the data from the two decoders, the RLC15discards data from one of the decoders only.

The detector16is a circuit for detecting the no defect in the data subjected to the selective combining process in the RLC15for a predetermined period of time or detecting the presence of a defect in the data subjected to the selective combining process in the RLC15and reporting the detected content to the reception controller17.

According to the result of detection in the detector16and also from the multi-path timing detected in the path searcher18, the reception controller17controls the operation of the finger for receiving the data from the base station. The reception controller17also detects the difference between the timings of data reception from the base stations21and22, respectively (hereinafter referred to as base station off-set), and controls, with the base station off-set, the interruption and resumption of the data processes in the fingers, the RAKE adder13b, the decoder14band the RLC15. The reception controller further controls the selector12such as to transmit the data from the fingers de-spreading data from the base station21to the RAKE adder13aand transmit the data from the fingers de-spreadng data from the base station22to the RAKE adder13b.

The path searcher18is a circuit for detecting the timing of the multiplying of the received signals (i.e., multi-path wave) and the spread code by one another by taking the correlation of the spread codes of the received signals and a pilot signal.

In this embodiment of the portable terminal set, as shown inFIG. 2, a portable terminal set23receives signals from the base stations21and22at a time in the neighborhood of the boundary between the base stations22and23.

FIG. 3shows the reception of data from a plurality of base stations when the portable terminal set23is in base station boundary neighborhood. In the example shown inFIG. 3, the portable terminal set23is receiving the same data from the base stations21and22. However, the data from the base station22is transmitted and received later than the data from the base station21.

FIG. 4is a block diagram showing the arrangement of each finger11ishown inFIG. 1. The finger11iincludes a pilot channel code generator41, a data channel code generator and a channel estimator43.

The pilot channel code generator41causes de-spread of the pilot signal by multiplying the pilot signal and the spread signal by each other at the timing of reception of the spread code from the reception controller17. The data channel code generator42causes de-spread of the received signals by multiplying the received signals and the spread code by one another at the timing of reception of the spread code from the reception controller17. The channel estimator43executes, by using the inversely dispersed pilot signal, a process of canceling the adverse effects of fading or the like on the received signals (hereinafter referred to channel estimation).

Now, the data receiving process in the embodiment of the portable terminal set will be described with reference toFIG. 5.

When the portable terminal set23comes to the boundary between the coverage areas of the base stations22and21(as shown inFIG. 2) during its data reception in the coverage area of the base station21with common channel MBMS, for evading the quality deterioration of the received signals, it starts reception of the received signals of the same data from the base stations21and22(step S501). The received signal of the data from the base station21is inputted via the fingers11, the selector12, the RAKE adder13aand the decoder14ato the RCL15. When the data from the base station21has been inputted to the RLC15for a predetermined period of time, the RLC15executes the selective data combining process on the data and outputs the resultant data to the detector16. The detector16makes a check as to whether data obtained in the selective data combining process in the RLC5has any defect (step S502). The data defect check is made by confirming the content of the header added to the data. To the header, continuous numbers are assigned. When no data defect is present, the header content is constituted by continuous numbers.

When no data defect is found in the data from the base station21(step S502/“YES”), the detector16transmits, to the reception controller17, data indicative of the fact that no defect is present in the data from the base station21. The reception controller17receiving the data confirms the base station off-set with respect to the base station22from the base station21, and determines the circuit for interrupting the process (steps S503, S505and S507). This is done so because if the reception of data from the base station22is interrupted irrespective of the base station off-set, depending on the base station off-set it is no longer in time to receive defective data by resuming the reception of the data from the base station22after detection of a defect in the data from the base station21. Specifically, when the base station off-set is longer than the sum of the times taken in the processes in the fingers11for receiving data from the base station22, the RAKE adder13b, the decoder14band the RLC15(step S503/“YES”), the reception controller17interrupts the de-spread of the data from the base station22in the fingers and the processes in the RAKE adder13b, the decoder14band the RLC15(step S504). When the base station off-set is shorter than the above sum of times but longer than the sum of the times required for the processes in the RAKE adder13b, the coder14band the RLC15(step S502/“NO”, step S505/“YES”), the reception controller17interrupts only the processes in the RAKE adder13b, the decoder14band the RLC15(step S506). When the base station off-set is shorter than the above time sum but longer than the sum of the times required for the processes in the decoder14and the RLC15(step S505/“NO” and step507/“YES”), in step S508the reception controller17interrupts the processes in the decoder114band RLC15. When the base station off-set is shorter than any of the above time sums (step S507/“NO”), the reception controller17does not interrupt the processes in the individual circuits.

As shown above, when the processes of the data received from the base station22are partly interrupted according to the value of the base station off-set, only the decoding result from the decoder14aas data from the base station21is inputted to the RLC15(this state being referred to as selective combining reception waiting state). In the selective combining reception waiting state, the detector16monitors for any defect present in the data inputted from the decoder14ato the RLC15(step S509). When the detector16detects a defect in the data (step S509/“YES”), it transmits this data to the reception controller17. The reception controller17receiving the data resumes the de-spread in the fingers and processes in the RAKE13band the decoder14bconcerning the data from the base station22, of which data the de-spread and processes have been interrupted according to the base station off-set (step S510).

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the present invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting.