GB2346770A

GB2346770A - Method for compensating for transmission power deviations of channels in a mobile phone

Info

Publication number: GB2346770A
Application number: GB9929699A
Authority: GB
Inventors: Hak-Hwan Kim
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 1998-12-16
Filing date: 1999-12-16
Publication date: 2000-08-16
Anticipated expiration: 2019-12-16
Also published as: GB2346770B; GB9929699D0; KR20000039916A; KR100322014B1

Abstract

Differences between transmitter power levels in allocated channels available for use by a mobile phone are compensated using so-called adjustment channels. These adjustment channels e.g. 991, 1, 120 are selected from among those that are available for all mobile phone communications and are fewer in number than the allocated channels. Thus 20 allocated channels form groups of one or more lying between the adjustment channels, of which one 363 is a reference channel and is also an allocated channel. The transmitter power level is controlled by an AGC circuit (Fig. 1 notshown) and the AGC control signal level for each adjustment channel e.g. as shown in Fig 2 is stored in a ROM. The AGC levels for the allocated channels are derived by interpolating from the level values associated with the adjustment channels on either side (Fig 3 not shown). Thus less data need be stored and fewer measurements made to establish the AGC levels necessary to produce the desired transmitter power taking into account variations in propagation parameters and hardware characteristics.

Description

METHOD FOR COMPENSATING FOR TRANSMISSION POWER DEVIATIONS OF CHANNES IN A MOBILE PHONE The present invention relates to a mobile phone, and more particularly to a method for reducing transmission power deviations of channels in a mobile phone.

Typically, a mobile phone uses particular channels for mobile phone services allocated thereto.

For instance, 20 channels are allocated as available channels for cellular mobile communications in Korea.

These available channels are selected from advanced mobile phone service (AMPS) channels. The AMPS channel numbers of such available channels are 1011, 29,70,111,152,193,234,275,316,363,404,445, 486,527,568,609,650,697,738, and 779.

Meanwhile, transmission power for each available channel in a mobile phone should meet the requirements of specific appropriate standards. In a mobile phone, however, transmission power may vary among different channels even at the same automatic gain control (AGC) level because the frequency characteristics of a radio frequency (RF) module used in the mobile phone may vary among those channels.

Furthermore, even in the case of mobile phones of the same model manufactured by the same manufacturer, a difference in transmission power is exhibited for the same channel because those mobile phones may have different hardware characteristics. Transmission power variations among different channels or transmission power differences among different phone sets for the same channel are called"transmission power deviations of channels". In the case of high deviations between transmission powers of channels, a poor maximum tansmission power or a poor open loup power in a certain channel may result.

In order to reduce such transmission power deviations of channels, the manufacturer may conduct, for each phone set manufactured, measurement of transmission power for each available channel while varying an AGC level, and then adjust the transmission power for each available channel to a desired level, based on the measured transmission power. In this case, transmission AGC levels corresponding to desired transmission power are stored in a non-volatile memory so that they can be used for available channels during practical use of the phone. For the non-volatile memory, an electrically erasable and programmable ROM (EEPROM) is typically used.

However, much time is taken for the above method in which transmission AGC levels obtained after conducting, for each phone set, a measurement of transmission power for available channels, which are typically 20 in number, and then conducting an adjustment of transmission power based on the measured transmission power, are stored in a nonvolatile memory. Furthermore, repetition of the above lengthy processes for all available channels in each phone set may result in a degradation in the performance of the phone set.

To reduce the above mentioned problem, a method may be proposed in which adjustment channels are used, the number of which is less than the number of available channels. That is, desired transmission AGC level values are derived only for the adjustment channels, and then stored in the non-volatile memory of a portable phone. In this case, the desired transmission power of available channels for a mobile phone may be determined when the mobile phone is being used. In other words, the determination of a desired transmission power is made only for a channel currently available, based on the stored transmission AGC level values. This is because the current available channel may vary in optimum transmission power depending on the characteristics thereof.

Thus, the number of channels is reduced, for which certain processes are required in the process of manufacturing mobile phones. The processes include measuring transmission power, adjusting the transmission power, deriving transmission AGC levels of those channels in association with the adjusted transmission power, and storing the derived transmission AGC levels in a non-volatile memory.

Accordingly, the above process is simplified, thereby reducing the above mentioned problems.

However, where such a method is used, it is necessary to compensate efficiently and accurately for the transmission AGC levels stored in the nonvolatile memory for the currently available channel.

If such accurate and efficient compensation is not undertaken high transmission power deviations of channels resulting in errors in transmission power may occur in practice even though the problems involved in the manufacture of the mobile phone ghave been eliminated Therefore, an object of the invention is to provide a method for compensating for transmission power deviations of channels, which is capable of reducing transmission power deviations of channels while efficiently compensating for those transmission power deviations.

Accordingly, a first aspect of the present invention provides a method for compensating transmission power deviations of channels in a mobile phone using adjustment channels selected from channels for supporting mobile phone services, the adjustment channels including a reference channel that is one of available channels allocated to the mobile phone from the channels for supporting mobile phone services, the number of the adjustment channels being less than the number of the allocated available channels, the mobile phone including a non-volatile memory stored with respective transmission automatic gain control (AGC) level values for the adjustment channels derived in accordance with an adjustment for transmission power at desrired level level for each of the adjustment channels, the method comprising the steps of: deriving offset values corresponding to respective differences between the transmission AGC level value of the reference channel and respective transmission AGC level values of the remaining adjustment channels; and deriving a compensation value for a currently available channel of the allocated available channels using offset values of the adjacent upper and lower adjustment channels and a transmit power level for the reference channel; and transmitting a signal from the mobile phone at a power level derived from the compensation valve.

In accordance with an embodiment of the present invention, this object is accomplished by providing a method for compensating transmission power deviations of channels in a mobile phone using adjustment channels selected from channels for supporting mobile phone services including as a reference channel one of the available channels allocated to the mobile phone from the channels for supporting mobile phone services, the number of the adjustment channels being less than the number of the allocated available channels, the mobile phone including a non-volatile memory stored with respective transmission automatic gain control (AGC) level values for the adjustment channels derived in accordance with an adjustment for transmission power at a desired level for each of the adjustment channels, the method comprising: deriving, from the AGC level values, offset values corresponding to respective differences between the transmission AGC level value of the reference channel and respective transmission AGC level values of the remaining adjustment channels; and deriving a compensation value for a currently available channel of the allocated available channels, based on offset values of upper and lower limit adjustment channels, among the adjustment channels, approaching upwardly and downwardly to the currently available channel, respectively, and respective channel spans between the currently available channel and the upper and lower limit adjustment channels, while using the following expression: ~ ffset) x (ch-min ch) +min ch o span where,"ch~pwr offset"represents the compensation value,"max~ ch~offset"and "min ch offset"represent the offset values of the upper and lower limit adjustment channels, respectively,"span"represents the channel span between the upper and lower limit adjustment channels,"ch"represents the channel No. of the currently available channel, and"min ch"represents the channel No. of the lower limit adjustment channel.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a block diagram illustrating the configuration of a mobile phone to which the present invention is applied; Figure 2 is a graph of a polygonal line for a transmission AGC level comparison among adjustment channels in accordance with an embodiment of the presentinvention; Figure 3 is a diagram illustrating a compensation value calculation according to the embodiment of the present invention; Figure 4 is a flow chart illustrating an offset value processing procedure according to the embodiment of the present invention; and Figure 5 is a flow chart illustrating a compensation value processing procedure according to the embodiment of the present invention.

Reference will now be made in detail to the preferred embodiments of the present invention. In the following description made in conjunction with a preferred embodiment of the present invention, a variety of specific elements such as the number of channels, channel Nos., and other various values are described. The description of such elements has been made only for a better understanding of the present invention. Those skilled in the art will appreciate that the present invention can be implemented without using the above mentioned specific elements. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. Also, the present invention will be described in conjunction with an example in which it is applied to mobile phones of a CDMA system.

Figure 1 is a block diagram illustrating the configuration of a mobile phone to which the present invention is applied. Referring to figure 1, a control unit 100 is illustrated which serves to conduct processing of speech signals and data for general conversations and data communications through the mobile phone while controlling parts of the mobile phone. Connected to the control unit 100 are an EEPROM 102, a flash memory 104, a RAM 106, a key pad 108, a display unit 110, an RF module 114, a baseband processing unit 116, and a coder/decoder (CODEC) 118, as shown in figure 1. The control unit 100 may comprise a mobile system modem chip manufactured by, for example, QUALCOMM Company. The mobile system modem chip includes a microprocessor, a CDMA processing unit, and a vocoder. In the following description, processing and control operations of the control unit 100 for general conversations and data communications through the mobile phone and other additional functions, which have no direct relation with the present invention, will not be described.

The EEPROM 102 coupled to the control unit 100 stores with transmission AGC levels and a variety of reference data therein. Programs for the processing and controlling operations of the control unit 100 are stored in the flash memory 104. The RAM 106 provides a working memory for the control unit 100. The key pad 108 is provided with a variety of keys including numeric keys to apply a key input generated by the user to the control unit 100. The display unit 108 is typically provided with an LCD to display a variety of information in the form of an image under the control of the control unit 100. The RF module 114 conducts transmission and reception of RF signals with a base station via an antenna 112. When the RF module 114 receives an RF signal, it converts the received RF signal into an intermediate frequency (IF) signal, and then sends the IF signal to the baseband processing unit 116. The RF module 114 receives an IF signal from the baseband processing unit 116, and then converts it into an RF signal which is, in turn, transmitted via the antenna 112. The RF module 114 conducts transmission power adjustment for the signal to be transmitted therefrom.

The baseband processing unit 116 is a baseband analog (BBA) ASIC for providing an interface between the control unit 100 and the RF module 114. This baseband processing unit 116 serves to convert a digital baseband signal into an analog IF signal which is, in turn, applied to the RF module 114. The baseband processing unit 116 also converts an analog IF signal received from the RF module 114 into a digital baseband signal which is, in turn, applied to the control unit 100. The CODEC 118 connected to the control unit 100 is coupled to a microphone 120 and a speaker 122. The CODEC 118 encodes a speech signal received from the microphone 120 in accordance with a pulse code modulation (PCM) encoding method, and then sends the resultant speech data to the control unit 100. The CODEC 118 also PCM-decodes speech data received from the control unit 100, and then sends the resultant speech signal to the speaker 122.

The transmission AGC levels stored in the EEPROM 102, which is a non-volatile memory, are those obtained after adjusting transmission power for the adjustment channels to desired levels, respectively.

The number of the adjustment channels is less than the number of available channels associated with the mobile phone. In an embodiment of the present invention, 10 adjustment channels, which corresponds to half the number of available channels, that is, 20, as mentioned above, are selected from the AMPS channels. The transmission AGC levels measured in practice for the adjustment channels are described in Table 1. Also, figure 2 is a graph of a polygonal line for a transmission AGC level comparison among the adjustment channels.

Table 1 Adjustment Channel Transmission AGC No. Level 991 209 1 208 120 209 240 209 363 212 480 214 560 217 640 223 720 229 799 234 The values of transmission AGC levels described in Table 1 are applied to the RF module 114. These values may vary depending on the hardware or characteristics of the RF module 114. Between the 10 adjustment channels and the 20 available channels, there is only one common channel. The number of the common channel is 363. The adjustment channels other than adjustment channel No. 363 do not correspond to any of the available channels. Accordingly, adjustment channel No. 363 is used as a reference channel upon conducting transmission power compensation for the available channels.

Each of the available channels is located between two neighbouring adjustment. In this regard, the transmission AGC level of an available channel can be derived from the transmission AGC levels of upper and lower limit adjustment channels approaching upwardly and downwardly thereto in channel number, respectively. If the transmission AGC level difference of the currently available channel from the reference channel is known, it is then possible to achieve compensation for the transmission power deviation of the currently available channel by using the known transmission AGC level difference as an offset value from the transmission AGC level of the reference channel upon the compensation. That is, the transmission AGC level difference is a compensation value used to compensate the currently available channel for the transmission power deviation. This compensation value may be referred to as a"channel power offset value"in that it is considered as a value for applying an offset to the transmission AGC level of the reference channel.

Where the currently available channel is the reference channel, it is unnecessary to conduct a derivation of the compensation value because the transmission AGC level of the reference channel is used as it is.

The offset value for each adjustment channel from the reference channel, which corresponds to the transmission AGC level difference between those two channels, as shown in Table 1, is described in Table 2.

Table 2

Adjustment Transmission Offset Channel No. AGC Level Value Value 991 209-3 1 208-4 120 209-3 240 209-3 363 212 0 480 214 2 560 217 5 640 223 11 720 229 17 799 234 22 To compensate appropriately for transmission power deviations of channels, it is necessary to derive accurately and efficiently compensation values for the available channels. A method for deriving compensation values in accordance with an embodiment of the present invention will now be described in conjunction with figure 3. In figure 3,"ch"denotes the number of the currently available channel for which a compensation value is to be derived, "max-ch"and"min-ch"represent upper and lower limit adjustment channels approaching upwardly and downwardly to the currently available channel current-ch in channel number, respectively,"span" represents the channel span between the upper and lower limit adjustment channels maxch and mincA.

For example, where the currently available channel No. is 193, it exists between the adjustment channel Nos. 120 and 240, as shown in Table 1. Accordingly, the upper and lower limit adjustment channel nos. associated with the currently available channel are 120 and 240, respectively. In this case, therefore, the channel span corresponds to 120 (240-120 = 120). In figure 3,"min~ch offset"and "max~ ch~offset"represent offset values for the upper and lower limit adjustment channels corresponding to the transmission AGC level difference between the reference channel and the upper limit adjustment channel and the transmission AGC level difference between the reference channel and the lower limit adjustment channel, as described in Table 1, respectively. The term"ch~ pwr~offset"represents a compensation value for compensating for a transmission power deviation of the currently available channel.

As shown in figure 3, the compensation value ch pwr offset can be expressed by a general linear equation, that is,"y = mx + b" (where,"m" represents a gradient, and"b"represents an offset value shown in Table 2). Accordingly, the compensation value chpwroffset can be derived from the following Expression 1 : [Expression 1] ch~pwr~offset=(max~ch~ofset-min~ch~offset)x(ch-min~ch)+min~ch~offset span From the compensation value derived using the upper and lower limit adjustment channel nos. associated with the currently available channel along with respective offset values for the upper and lower limit adjustment channels, it is possible to derive an accurate transmission AGC level meeting the characteristics of the currently available channel.

Thus, respective compensation values for 20 available channels can be derived. Accordingly, the transmission AGC levels of the 20 available channels can be derived by adding the compensation values for the 20 available channels to the transmission AGC level of the reference channel, that is, the adjustment channel no. 363, respectively. The derived transmission AGC levels of the 20 available channels are depicted by the graph of the polygonal line shown in figure 2. Since transmission power deviations of channels can be accurately and efficiently compensated using the above mentioned method, it is possible to store the measured transmission AGC levels of only 10 adjustment channels, which corresponds to half of the number of available channels, that is, 20, in the EEPROM 102.

Accordingly, it is possible to reduce transmission power deviations of channels while simplifying and reducing the processes conducted by the manufacturer.

To derive the compensation value ch-pwr offset using the expression 1, it is necessary to first derive the lower limit adjustment channel no., that is, min-ch, and the channel span, that is, span. The values are derived at the manufacturing end through an appropriate calculation. The derived values can be arranged in an appropriate table using indexes so that they correspond to one of those indexes. An example of such a table is the following Table 3.

Table 3 shows respective indexed lower limit adjustment channel nos., min-ch, and respective indexed channel spans, span, for the adjustment channels of Table 1 associated with 20 available channels.

Table 3 Available Index Min-ch Span Channel 1011 0 991 33 29,70,111 1 1 119 152,193,234 2 120 120 275,316 3 240 123 363 404,445 4 363 117 486,527 5 480 80 568,609 6 560 80 650,697 7 640 80 738,779 8 720 79 In Table 3, the adjustment channel numbered as 363 is not allocated an index because it is the reference channel requiring no compensation. Where it is desired to derive a compensation value for the currently available channel in a practical mobile phone, this can be simply achieved using such a table in which lower limit adjustment channel Nos., minch, and channel spans, span, derived for adjustment channels are arranged while being allocated with indexes so that those associated with each adjustment channel correspond to at least one of the indexes.

This is because it is only necessary to search the table for the compensation value for the currently available channel without any calculation.

An example of an array for lower limit adjustment channel Nos., min-ch, is as follows: int2 chcompminch [9] = {991, 1,120,240,363, 480,560,640,720} An example of an array for channel spans, span, is as follows: int2 ch~comp~span [9] = {33, 119,120,123,117, 80,80,79} Now, the above method for compensating transmission power deviations of channels in accordance with an embodiment of the present invention will be described in conjunction with figure 4 illustrating an offset value processing procedure according to an embodiment of the present invention along with figure 5 illustrating a compensation value processing procedure according to an embodiment of the present invention.

The offset value processing procedure shown in figure 4 is conducted by the control unit 10 every time the mobile phone of figure 1 turns on. On the other hand, the compensation value processing procedure shown in figure 5 is periodically conducted at intervals of a predetermined time. For example, the compensation value processing interval is set to coincide with the transmission power adjustment processing interval. In this case, the compensation value processing interval is set to 1.25 ms, taking into consideration the fact that base stations of the current CDMA system conduct processing for transmission power adjustment at intervals of 1.25 ms. The reason why the offset value processing procedure of figure 4 is conducted every time the mobile phone turns on is because an offset value once calculated is stored in the RAM 106 so that it is kept unless the mobile phone turns off.

First, the offset value processing procedure will be described in conjunction with figure 4. When the mobile phone turns on, the control unit 100 reads out transmission AGC level values, as described in Table 1, for adjustment channels from the EEPROM 102 at step 200, as shown in figure 4. The read-out transmission AGC level values are then stored in the form of an array in the RAM 106. Thereafter, an offset value for each adjustment channel is derived by calculating the transmission AGC level difference between the reference channel and the adjustment channel at step 202. Offset values derived for all adjustment channels, as described in Table 2, are also stored in the form of an array in the RAM 106.

Next, the number of the reference channel, that is, 363, is stored as a parameter old ch in the RAM 106 at step 204. Thus, the offset value processing procedure is ended.

The offset values derived, when the mobile phone turns on, are used in the compensation value processing procedure of figure 5 to be conducted at intervals of a predetermined time.

In accordance with the compensation value processing procedure of figure 5, the control unit 100 stores the number of the currently available channel as a parameter currentch at step 300 when a predetermined compensation value processing interval begins. It is then checked at step 302 whether or not the parameter current~ch, that is, the number of the currently available channel, corresponds to 363.

Where the current available channel no., current ch, corresponds to 363, it is unnecessary to conduct any transmission power compensation because the current available channel is the reference channel. In this case, a value of 0 is stored as the channel power offset value, which is a compensation value for the current available channel, at step 318. Thereafter, the procedure returns to a normal routine. On the other hand, when it is determined at step 302 that the current available channel no., current ch, does not correspond to 363, the procedure proceeds to step 304. At step 304, it is checked whether or not the current available channel no., current ch, corresponds to the parameter old~ ch. Where the current available channel no., current-ch, corresponds to the parameter old ch, the previous compensation value is used as the current compensation value because there is no channel change. In this case, the procedure returns to the normal routine because no compensation value calculation is required. On the other hand, when it is determined at step 304 that the current available channel no., currentch, does not correspond to the parameter old ch, steps 306 to 316 are executed to derive a new compensation value because the current available channel is a new channel.

At step 306, the current available channel no., current, is stored as the parameter old ch. That is, the parameter old ch is updated with the current available channel no., current ch. At step 308, the index for the current available channel no., current ch, is then derived. Using the derived index, the above mentioned array is then searched for the channel span, span, and lower limit adjustment channel no., minch, associated with the current available channel at step 310.

Thereafter, the channel power offset value, which is the compensation value for the current available channel, is calculated at step 312, based on the derived the channel span, span, and lower limit adjustment channel no., min-ch, using expression 1. The calculated channel power offset value is then rounded off at step 314. The calculated channel power offset value is rounded off to obtain increased accuracy. The rounded-off channel power offset value is stored at step 316 so that it can be used for a transmission power compensation for the currently available channel.

Thereafter, the procedure returns to the normal routine.

As mentioned above, the compensation value for the currently available channel is derived, based on the relation of the current available channel with the adjustment channels approaching upwardly and downwardly thereto and respective transmission AGC level differences of those adjustment channels from the reference channel. Using this compensation value, it is possible to obtain an accurate transmission AGC level of the current available channel meeting the characteristics of the current available channel. This makes it possible to store the measured transmission AGC levels of adjustment channels, which corresponds in number to half the number of available channels, in an EEPROM.

As apparent from the above description, the present invention provides advantages in that it uses adjustment channels, the number of which is less than the number of available channels, while deriving an accurate compensation value for a channel currently available by use of the upper and lower limit adjustment channel nos. associated with the current available channel along with respective offset values for the upper and lower limit adjustment channels, thereby reducing and efficiently compensating for the transmission power deviation of the current available channel.

While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment, but, on the contrary, it is intended to cover various modifications within the spirit and scope of the appended claims. Although the compensation value processing procedure has been described as being conducted at intervals of a predetermined time, and the offset value processing procedure has been described as being conducted only when the mobile phone turns on, the present invention is limited to such conditions. Other conditions for those procedures may be used in so far as the offset value processing procedure is conducted prior to the compensation value processing procedure. In the illustrated embodiment, the processing step for determining whether or not a channel change is made and the processing step for determining whether or not the current available channel is the reference channel are conducted in order to reduce the amount of calculation required. However, these processing steps may be eliminated.

Claims

CLAIMS 1. A method for compensating transmission power deviations of channels in a mobile phone using adjustment channels selected from channels for supporting mobile phone services, the adjustment channels including a reference channel that is one of available channels allocated to the mobile phone from the channels for supporting mobile phone services, the number of the adjustment channels being less than the number of the allocated available channels, the mobile phone including a non-volatile memory stored with respective transmission automatic gain control (AGC) level values for the adjustment channels derived in accordance with an adjustment for transmission power at desrired level level for each of the adjustment channels, the method comprising the steps of: deriving offset values corresponding to respective differences between the transmission AGC level value of the reference channel and respective transmission AGC level values of the remaining adjustment channels; and deriving a compensation value for a currently available channel of the allocated available channels using offset values of the adjacent upper and lower adjustment channels and a transmit power level for the reference channel; and transmitting a signal from the mobile phone at a power level derived from the compensation valve.
2. A method as claimed in claim 1, in which the step of deriving includes the step of calculating the compensation value by interpolating between the offset vales of the adjacent upper and lower adjustment channels.
3. A method as claimed in claim 2, in which the step of calculating use the following expression: ch~pwr~o1Nser=----x (ch-mm~ch) +mm~ch~ofset span where, offset"represents the compensation value,"max ch offset"and "minchoffset"represent the offset values of the upper and lower limit adjustment channels, respectively,"span"represents the channel span between the upper and lower limit adjustment channels,"ch"represents the channel No. of the currently available channel, and"min ch" represents the channel No. of the lower limit adjustment channel.
4. A method according to claim 3, in which respective channel spans and respective lower adjustment channel Nos. associated with the available channels, except for the reference channel, are stored in an array and allocated indexes corresponding to at least one of the available channels.
5. A method as claimed in claim 4, in which the channel span and the lower adjustment channel No. associated with the currently available channel are derived by deriving the index of the currently available channel, and searching the array for the channel span and the lower adjustment channel No. associated with the currently available channel.
6. A method as claimed in any preceding claim, in which the number of the adjustment channels corresponds to half the number of the available channels.
7. A method as claimed in any preceding claim, in which the derived compensation value is rounded off.
8. A method as claimed in any preceding claim, in which the step of deriving the compensation valve is performed at pre-determined intervals of time.
9. A method as claim in any preceding claim, further comprising the steps of: checking whether or not the currently available channel corresponds to the reference channel; when the currently available channel corresponds to the reference channel, determining the compensation value for the currently available channel to be"0" ; when the currently available channel does not correspond to the reference channel, checking whether or not the currently available channel corresponds to the available channel just previous to the currently available channel; when the currently available channel does not correspond to the previous available channel, calculating the compensation value for the currently available channel, and updating the compensation value previously derived for the previous available channel with the currently derived compensation value; and when the currently available channel corresponds to the previous available channel, keeping the compensation value previously derived for the previous available channel, so that the previously derived compensation value is used as a compensation value for the currently available channel.
10. A method for compensating for transmission power deviations of channels of a mobile phone substantially as described herein with reference to and/or as illustrated in the accompanying drawings.
11. Apparatus for compensating transmission power deviations of channels in a mobile phone using adjustment channels selected from channels for supporting mobile phone services, the adjustment channels including a reference channel that is one of available channels allocated to the mobile phone from the channels for supporting mobile phone services, the number of the adjustment channels being less than the number of the allocated available channels, the mobile phone including a non-volatile memory stored with respective transmission automatic gain control (AGC) level values for the adjustment channels derived in accordance with an adjustment for transmission power at desrired level level for each of the adjustment channels, the apparatus comprising: means for deriving offset values corresponding to respective differences between the transmission AGC level value of the reference channel and respective transmission AGC level values of the remaining adjustment channels; and means for deriving a compensation value for a currently available channel of the allocated available channels using offset values of the adjacent upper and lower adjustment channels and a transmit power level for the reference channel; and means for transmitting a signal from the mobile phone at a power level derived from the compensation valve.
12. An apparatus as claimed in claim 11, in which the means for deriving includes the means of calculating the compensation value by interpolating between the offset vales of the adjacent upper and lower adjustment channels.
13. An apparatus as claimed in claim 12, in which the means of calculating usew the following expression: ch~pwr~offset=(max~ch~offset-min~ch~offset)x(ch-min~ch)+min~ch+~offset span where,"ch~par~offset"represents the compensation value,"max ch offset"and "minchoffset"represent the offset values of the upper and lower limit adjustment channels, respectively,"span"represents the channel span between the upper and lower limit adjustment channels,"ch"represents the channel No. of the currently available channel, and"min ch" represents the channel No. of the lower limit adjustment channel.
14. An apparatus as claimed in claim 13, in which respective channel spans and respective lower adjustment channel nos. associated with the available channels, except for the reference channel, are stored in an array and allocated indexes corresponding to at least one of the available channels.
15. An apparatus as claimed in claim 14, in which the channel span and the lower adjustment channel no. associated with the currently available channel are derived by deriving the index of the currently available channel, and searching the array for the channel span and the lower adjustment channel no. associated with the currently available channel.
16. An apparatus as claimed in any of claims 11 to 15, in which the number of the adjustment channels corresponds to half the number of the available channels.
17. An apparatus as claimed in any of claims 11 to 16, in which the derived compensation value is rounded off.
18. An apparatus as claimed in any of claims 11 to 17, in which the means for deriving the compensation valve is invoked at pre-determined intervals of time.
19. A method as claim in any of claims 11 to 18, further comprising means for checking whether or not the currently available channel corresponds to the reference channel; means for, when the currently available channel corresponds to the reference channel, determining the compensation value for the currently available channel to be"0"; means for, when the currently available channel does not correspond to the reference channel, checking whether or not the currently available channel corresponds to the available channel just previous to the currently available channel; means for, when the currently available channel does not correspond to the previous available channel, calculating the compensation value for the currently available channel, and updating the compensation value previously derived for the previous available channel with the currently derived compensation value ; and means for, when the currently available channel corresponds to the previous available channel, keeping the compensation value previously derived for the previous available channel, so that the previously derived compensation value is used as a compensation value for the currently available channel.
20. An apparatus for compensating for transmission power deviations in a channel of a mobile phone substantially as described herein with reference to and/or as illustrated in the accompanying drawings.
21. A mobile phone operable according to a method as claimed in any of claim 1 to 10.
22. A mobile phone comprising apparatus as claimed in any of claims 11 to 20.