JP2010226600A - Radio communication terminal and communication system selecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication terminal and communication system selecting method for selecting an optimal communication system so as to meet required throughput while keeping a residual battery time long. <P>SOLUTION: A radio communication terminal 100 includes a penalty value calculator and a system selector. The penalty value calculator calculates a penalty value of each of communication systems in a current communication environment in accordance with a penalty function. The penalty function is an increasing function of power consumption by communication and is a decreasing function of which dependency on throughput is small in a range where throughput of communication is greater than a predetermined value, and of which dependency on throughput is large within a range where throughput is smaller than the predetermined value. The system selector selects a communication system of the smallest penalty value calculated. Thus, a switching destination to increase power consumption or throughput deterioration is hardly selected, thereby selecting the optimal communication system. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication terminal capable of selecting a plurality of communication methods and a communication method selection method for selecting an optimum communication method.

  In so-called multi-mode terminals, there are known a method of switching each method on hardware and a method of operating each method by rewriting software so that a plurality of communication methods can be selected. Conventionally, reception quality such as RSSI and CINR for each method, throughput, power consumption, and composite indexes thereof are used as standards for method selection / switching (for example, Patent Document 1). The composite mobile phone device described in Patent Document 1 selects the method with the lowest power consumption when the remaining battery level is below a preset threshold value.

  In a multi-mode terminal, when the reception environment of each method changes, the method is frequently switched, and power consumption and throughput loss for switching itself cannot be ignored. Therefore, a method selection method that takes into consideration power consumption and throughput loss required for switching itself has been proposed (see, for example, Patent Document 2). The wireless communication terminal described in Patent Literature 2 measures reception quality (RSSI, CINR, etc.) and calculates a channel fluctuation value from the measurement value. And it switches according to the calculated fluctuation value using the threshold value regarding the reception quality set in advance. This operation avoids frequent switching of methods.

Japanese Patent No. 4085748 JP 2006-262178 A

  However, the composite mobile phone device described in Patent Document 1 selects the method with the lowest power consumption when the threshold value for the remaining battery level is set in advance, but selects the method according to the radio wave condition when the threshold value is exceeded. In that case, among the multiple communication methods, the method with the best radio wave condition is unlikely to match the method with the lowest power consumption, and the communication method with the lowest power consumption satisfies the required throughput. Unlikely. Therefore, when the threshold of the remaining battery level is set high, there is a possibility of selecting a method that consumes the lowest power but has extremely low throughput and cannot satisfy the user's request. On the other hand, if it is set to a low value, a method is selected that has a throughput that is higher than necessary and that consumes a large amount of power, and the battery remaining time is likely to be shortened. Therefore, the composite mobile phone device described in Patent Document 1 cannot satisfy the user's required throughput while keeping the battery remaining time long.

  Conventionally, there are cases where switching between methods frequently occurs, and there is a problem of power consumption and throughput degradation due to the same processing. In particular, when a multi-mode terminal is operated by software radio technology, rewriting of software is necessary for switching the method, and the influence of the switching becomes large.

  On the other hand, the amount of power consumption and throughput degradation when changing the method should be different depending on the combination of the method in use and the method of the switching destination, but the wireless communication terminal described in Patent Document 2 The switching destination cannot be selected in consideration of the combination. For this reason, when switching is required, power consumption and throughput deteriorate greatly depending on the switching destination. In addition, it is necessary to add processing for calculating a communication quality fluctuation value, adaptive threshold setting, and updating, and it is necessary to load some memory.

  The present invention has been made in view of such circumstances, and provides a wireless communication terminal and a communication method selection method for selecting an optimal communication method so as to satisfy a user's required throughput while maintaining a long battery remaining time. With the goal.

  (1) In order to achieve the above object, a wireless communication terminal of the present invention is a wireless communication terminal capable of selecting a plurality of communication methods, is a function of increasing power consumption by communication, and has a predetermined communication throughput. In the range larger than the value, the dependence on the throughput is small, and in the range where the throughput is smaller than the predetermined value, the penalty function which is a decreasing function having a large dependence on the throughput, the communication function in the current communication environment A penalty value calculating unit that calculates a penalty value and a method selecting unit that selects a communication method having the smallest calculated penalty value are provided.

  As described above, the wireless communication terminal of the present invention uses a penalty function that refers to the power consumption and communication throughput by communication, makes it difficult to select a switching destination that greatly deteriorates power consumption and throughput, and optimizes the communication method. Select. For example, since the dependence on the throughput is small in the range where the throughput is larger than a predetermined value, the magnitude of the power consumption is effective for the penalty value. On the other hand, in the range where the throughput is smaller than the predetermined value, it is a decreasing function having a large dependence on the throughput. Therefore, if the throughput is small, the small penalty value becomes large and the influence on the penalty value of the throughput becomes large.

  Therefore, when the demand for throughput is low and the predetermined value is small, power consumption is emphasized and a communication method is selected. On the other hand, when the demand for throughput is high and the predetermined value is large, the communication method is selected with an emphasis on throughput rather than power consumption. As a result, the wireless communication terminal of the present invention can perform an optimal method selection so as to satisfy the user's required throughput while keeping the battery remaining time long. For example, even when the remaining battery capacity is sufficient, a method with low power consumption can be selected, so that the remaining battery time can be kept long. The increase function indicates an increase function in a broad sense, and includes a step function that increases stepwise. The same applies to the decreasing function.

  (2) Further, the wireless communication terminal of the present invention is characterized in that the penalty function is a function of increasing throughput loss due to switching of communication methods. As described above, the wireless communication terminal according to the present invention selects the optimum communication method change destination with reference to the throughput loss when the communication method is switched. The amount of throughput degradation when changing the method differs depending on the combination of the method being used and the method of the switching destination, but the switching destination can be selected in consideration of such a combination. As a result, frequent switching of the system can be avoided, and deterioration of throughput due to switching processing can be prevented.

  (3) Further, the wireless communication terminal of the present invention is characterized in that the penalty function is an increase function of switching power required for switching of communication methods. As described above, the wireless communication terminal according to the present invention selects an optimum communication method switching destination with reference to the extra power consumption at the time of switching the communication method. The power consumption for changing the method varies depending on the combination of the method being used and the method of the switching destination, but the switching destination can be selected in consideration of such a combination. As a result, frequent switching of the system can be avoided and power consumption due to the switching process can be prevented.

  (4) Also, the wireless communication terminal of the present invention refers to a predetermined table in which the throughput is associated with the communication environment evaluation and the communication method, and extracts the throughput associated with the specific communication environment and the communication method. An extraction unit is further provided. Thereby, it is possible to easily obtain a reasonable throughput of each communication method in consideration of a communication environment such as reception quality.

  (5) The communication method selection method of the present invention is a communication method selection method for selecting an optimal communication method in a wireless communication terminal, which is a function of increasing power consumption by communication, and the communication throughput is a predetermined value. In a larger range, the dependence on the throughput is small, and in a range where the throughput is smaller than a predetermined value, a penalty function which is a decreasing function having a large dependence on the communication throughput causes each communication method in the current communication environment. The method includes a step of calculating a penalty value, and a step of selecting a communication method having the smallest calculated penalty value. As a result, it is possible to select an optimum method so as to satisfy the user's required throughput while keeping the battery remaining time long.

  According to the present invention, it is possible to select an optimum method so as to satisfy the user's required throughput while keeping the battery remaining time long.

It is a block diagram which shows the basic composition of the radio | wireless communication terminal which concerns on this invention. It is a block diagram which shows the structure of a communication system control part. It is a flowchart which shows an example of the basic process of a communication system control part. It is a figure which shows an example of a predetermined table. It is a figure which shows an example of specific (delta) (i, j).

  Next, embodiments of the present invention will be described with reference to the drawings. In order to facilitate understanding of the description, the same reference numerals are given to the same components in the respective drawings, and duplicate descriptions are omitted.

(Configuration of wireless communication terminal)
FIG. 1A is a block diagram showing a basic configuration of radio communication terminal 100. As shown in FIG. 1A, a radio communication terminal 100 includes transmission / reception antennas 101a and 101b, an RF unit 102, an AD / DA conversion unit 103, a baseband signal processing unit 104, a communication environment acquisition unit 105, a communication method control unit 106, an application A request acquisition unit 107 and a software storage unit 108 are provided. As shown in FIG. 1A, the wireless communication terminal 100 is a software defined radio, but may be a terminal that implements a plurality of communication methods by hardware. Thus, the wireless communication terminal 100 can select a plurality of communication methods.

  The transmission / reception antennas 101a and 101b transmit and receive a high frequency modulated corresponding to the communication method. The RF unit 102 converts the received high frequency into a baseband signal and converts the baseband signal received from the AD / DA conversion unit 103 into a high frequency. The AD / DA conversion unit 103 converts the baseband signal from an analog signal to a digital signal, or from a digital signal to an analog signal. The baseband signal processing unit 104 processes the baseband signal according to the currently selected wireless communication method. The communication environment acquisition unit 105 acquires communication environment parameters such as CINR and sends them to the communication method control unit 106. This makes it possible to select a communication method that takes into account the evaluation of the communication environment.

  The communication system control unit 106 controls selection and change of the communication system. That is, the communication method is selected based on the communication environment parameter (for example, CINR value) of each communication method acquired by the communication environment acquisition unit 105 and the user request acquired by the application request acquisition unit 107, that is, the request throughput (predetermined value). To do. Also, the software corresponding to the selected communication method is loaded into the baseband signal processing unit 104 and the RF unit 102 is controlled. Thereby, it is possible to easily obtain a reasonable throughput of each communication method in consideration of a communication environment such as reception quality. Details of the communication method control unit 106 will be described later.

  The application request acquisition unit 107 calculates a requested throughput by referring to the application request, and sends it to the communication method control unit 106. The software storage unit 108 stores software corresponding to each communication method.

  FIG. 1B is a block diagram illustrating a configuration of the communication method control unit 106. As shown in FIG. 1B, the communication method control unit 106 includes a penalty value calculation unit 111, a throughput extraction unit 112, a method selection unit 113, and a change control unit 114.

  The penalty value calculation unit 111 calculates a penalty value for each communication method using a penalty function. The penalty function is a function of increasing power consumption due to communication. The penalty function is less dependent on the throughput in a range where the communication throughput is larger than the required throughput in the current communication environment. On the other hand, the penalty function has a large dependence on the throughput and is a decreasing function in a range where the throughput is smaller than a predetermined value. The penalty function is a function for increasing the switching power required for switching the communication method, and is a function for increasing throughput loss (throughput degradation amount) due to switching of the communication method. A specific example of the penalty function will be described later.

  The throughput extraction unit 112 refers to a predetermined table that associates throughput with communication methods and communication environment parameters, and extracts any of the associated throughputs. The throughput extraction unit 112 receives a designation from the penalty value calculation unit, acquires communication environment parameters such as reception quality information (CINR or RSSI), and sets the communication method specified by the penalty value calculation unit 111 and the acquired communication environment parameters. Extract the corresponding throughput.

  The method selection unit 113 selects a communication method having the smallest calculated penalty value. As described above, the wireless communication terminal 100 selects an optimal communication method using a penalty function that refers to power consumption determined for each communication method and throughput determined for each communication method. Therefore, it is difficult to select a switching destination that greatly degrades power consumption and throughput. As a result, it is possible to select an optimum method so as to satisfy the user's required throughput while keeping the battery remaining time long. For example, even when the remaining battery capacity is sufficient, a communication method with low power consumption can be selected, so that the remaining battery time can be kept long.

  The change control unit 114 controls each unit to change the communication method when the communication method selected by the method selection unit 113 is different from the communication method currently employed. For example, the software corresponding to the selected communication method is loaded into the baseband signal processing unit 104 and the RF unit 102 is controlled.

(Operation of communication method selection by wireless communication terminal)
FIG. 2 is a flowchart illustrating an example of basic processing of the communication method control unit 106. In FIG. 2, i represents an index of a communication method, and j represents a communication method currently used. N represents the number of systems supported by the terminal.

  In FIG. 2, the CINR value is acquired by the communication environment acquisition unit 105 of the method corresponding sequentially from i = 1, and the transmission rate bi and the required power consumption Pi that can be achieved by the target method are predicted. In the example of FIG. 2, a corresponding value is read from a predetermined table set in advance.

  As shown in FIG. 2, the radio communication terminal 100 first obtains the requested throughput (step S1) and initializes the communication method i to 1 (step S2). Then, the CINR of the communication method i is acquired (step S3), and the transmission rate bi [bps] and the power consumption Pi of the communication method i are extracted and stored using a predetermined table (step S4). A specific example of the predetermined table will be described later. Next, it is determined whether or not i = N, that is, whether or not extraction of the transmission rate bi and power consumption Pi has been completed for all communication methods (step S5).

  If it is determined that i = N is not satisfied, i is incremented by 1 (step S6), the next communication method is targeted, and the process returns to step S3. On the other hand, if it is determined that i = N, a penalty value Pi ′ is calculated for each communication method (step S7). Then, the communication method i that minimizes the penalty value Pi ′ is selected (step S8), and the process ends. In the above example, the penalty value Pi ′ is calculated collectively after the iteration loop. However, the penalty value Pi ′ may be calculated during the iteration loop.

(Example of a predetermined table)
FIG. 3 is a diagram illustrating an example of a predetermined table in which throughput is associated with communication environment evaluation and communication method. However, as for the required power consumption corresponding to each transmission rate of each communication method, a value obtained by performing calibration is written in the table. For example, when CINR is 20 dB when i = 1 and 27 dB when i = 2, it can be seen that transmission rates bi of 2.4 Mbps and 10 Mbps can be obtained, respectively. Note that the above table is an example, and specific numerical values differ depending on the method and each terminal.

(Example of penalty function)
Next, an example of the penalty function Pi ′ will be described. Equation (1) is an example of the penalty function Pi ′.

ε (bi) represents a function for imposing a penalty when the transmission rate bi of the communication method i is less than the required throughput value T. For example, a function as in the following equation (2) is used.

  For example, in the range where the throughput is larger than the required throughput value T, ε (bi) does not depend on the throughput, so the magnitude of the power consumption is effective for the penalty value. On the other hand, since the throughput is an inverse function of the throughput in a range smaller than the required throughput value T, the smaller the throughput, the larger the penalty value and the greater the influence on the throughput penalty value. Therefore, when the demand for throughput is low and the required throughput value T is small, power consumption is emphasized and a communication method is selected. On the other hand, when the demand for throughput is high and the required throughput value T is large, the communication method is selected with an emphasis on throughput rather than power consumption.

Further, δ (i, j) represents a function that imposes a penalty when a change of the communication method is required. For example, a function such as the following equation (3) is used.

  In this way, a communication system in which i ≠ j, that is, a communication system that requires a system change, is multiplied by an independent constant greater than 1.0 and each (i, j) combination. FIG. 4 is a diagram showing a more specific example of δ (i, j).

  In the example illustrated in FIG. 4, the wireless communication terminal 100 is targeted for three communication methods: a cellular A method, a cellular B method, and a wireless LAN. For example, switching times between cellular systems having higher network compatibility are shorter than those between cellular systems and wireless LANs (WLANs), and power consumption and throughput loss due to the processing are reduced. In this case, it is possible to make switching difficult by setting δ (i, j) between the cellular system and the wireless LAN large as illustrated. Note that δ (j, j) is 1 for the same communication method.

  In this way, by defining the penalty function independently between the communication methods, it becomes possible to control the method which is not easily switched to the method having a large influence by the switching. The wireless communication terminal 100 selects an optimal communication method switching destination with reference to extra power consumption at the time of switching the communication method and throughput loss at the time of switching the communication method. Although the power consumption and throughput loss required for changing the communication method differ depending on the combination of the method being used and the method of the switching destination, the switching destination can be selected in consideration of such a combination. As a result, frequent switching of systems can be avoided, and an increase in power consumption and throughput deterioration due to switching processing can be prevented.

  In the above embodiment, a multi-mode terminal that enables selection of a plurality of wireless communication schemes using software defined radio technology has been described as an example. However, a terminal that enables selection of a plurality of wireless communication schemes by hardware. The present invention can also be applied to the above.

100 Wireless communication terminals 101a, 101b Transmission / reception antenna 102 RF unit 103 AD / DA conversion unit 104 Baseband signal processing unit 105 Communication environment acquisition unit 106 Communication system control unit 107 Application request acquisition unit 108 Software storage unit 111 Penalty value calculation unit 112 Throughput Extraction unit 113 Method selection unit 114 Change control unit bi Transmission rate i Communication method Pi ′ Penalty function (penalty value)
Pi Power consumption T Required throughput value

Claims (5)

A wireless communication terminal capable of selecting a plurality of communication methods,
The dependence on the throughput is small when the communication throughput is a function of increasing power consumption and the communication throughput is larger than a predetermined value, and the dependence on the throughput is greatly decreased when the throughput is smaller than the predetermined value. A penalty value calculation unit that calculates a penalty value of each communication method in the current communication environment by a penalty function that is a function,
A wireless communication terminal comprising: a method selection unit that selects a communication method having the smallest calculated penalty value.   The wireless communication terminal according to claim 1, wherein the penalty function is a function of increasing throughput loss due to switching of communication methods.   The wireless communication terminal according to claim 1, wherein the penalty function is a function of increasing switching power required for switching a communication method.   2. A throughput extraction unit that extracts a throughput associated with a specific communication environment and a communication method by referring to a predetermined table in which the throughput is associated with the evaluation of the communication environment and the communication method. The wireless communication terminal according to claim 3. A communication method selection method for selecting an optimal communication method in a wireless communication terminal,
The dependence on the throughput is small when the communication throughput is a function of increasing power consumption and the communication throughput is larger than a predetermined value, and the dependence on the throughput is greatly decreased when the throughput is smaller than the predetermined value. Calculating a penalty value for each communication method in the current communication environment by a penalty function as a function;
Selecting a communication method having the smallest calculated penalty value.

Images