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Mobile Phone Patent Abstract
A method for compensating transmission power deviations of channels
in a mobile phone using adjustment channels, which is capable of
minimizing transmission power deviations of channels while efficiently
compensating for those transmission power deviations. The adjustment
channels are selected from channels for mobile phone services while
including a reference one of available channels allocated to the
mobile phone from the channels for mobile phone services, the number
of the adjustment channels being less than the number of the allocated
available channels. Respective transmission automatic gain control
(AGC) level values for the adjustment channels are stored in the
non-volatile memory of the mobile phone. The method involves an
offset value processing procedure for reading out the transmission
AGC level values from the non-volatile memory, and 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 a compensation
value processing procedure for deriving a compensation value for
a currently available one of the allocated available channels, based
on offset values of upper and lower limit adjustment channels, located
above and below the currently available channel, respectively, a
channel span between the currently available channel and the lower
limit adjustment channel, and a channel span between the upper and
lower limit adjustment channels.
Mobile Phone Patent Claims
What is claimed is:
1. A method for compensating transmission power deviations of channels
in a mobile phone using adjustment channels selected from channels
for mobile phone services while including a reference one of available
channels allocated to the mobile phone from the channels for 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,
said transmission AGC level values derived at an optimum level for
each of the adjustment channels, the method comprising: an offset
value processing procedure for reading out the transmission AGC
level values from the non-volatile memory, and 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 a compensation
value processing procedure for deriving a compensation value for
a currently available one of the allocated available channels, based
on offset values of upper and lower limit adjustment channels, located
above and below the currently available channel, respectively, a
channel span between the currently available channel and lower limit
adjustment channel, and a channel span between the upper and lower
limit adjustment channels, while using the following expression:
##EQU3## 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 number of the currently available channel, and "min_ch"
represents the channel number of the lower limit adjustment channel.
2. The method according to claim 1, wherein the number of the adjustment
channels corresponds to half the number of the available channels.
3. The method according to claim 1, wherein respective channel
spans between the upper and lower limit adjustment channels and
respective lower limit adjustment channel numbers associated with
each available channel except for the reference channel, are stored
in an array and allocated with indexes, each index corresponding
to at least one of the available channels.
4. The method according to claim 3, wherein the channel span and
the lower limit adjustment channel number associated with the currently
available channel are derived by deriving an index of the currently
available channel, and searching the array for the channel span
and the lower limit adjustment channel number associated with the
index of the currently available channel.
5. The method according to claim 2, wherein the derived compensation
value is rounded off.
6. A method for compensating transmission power deviations of channels
in a mobile phone using adjustment channels selected from channels
for mobile phone services while including a reference one of available
channels allocated to the mobile phone from the channels for 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,
said transmission AGC level values derived at an optimum level for
each of the adjustment channels, the method comprising: an offset
value processing procedure for reading out the transmission AGC
level values from the non-volatile memory when the mobile phone
turns on, and 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; a compensation value processing procedure for
deriving, at intervals of a predetermined time, a compensation value
for a currently available one of the allocated available channels,
based on offset values of upper and lower limit adjustment channels,
above and below the currently available channel, respectively, a
channel span between the currently available channel and the upper
and lower limit adjustment channel, and a channel span between the
upper and lower adjustment channels, while using the following expression:
##EQU4## 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 number of the currently available channel, and "min_ch"
represents the channel number of the lower limit adjustment channel.
7. The method according to claim 6, further comprising the steps
of: at every predetermined time interval, 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 that was checked in the last predetermined time period;
when the currently available channel does not correspond to the
previous available channel, executing the compensation value processing
procedure 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.
8. The method according to claim 7, wherein the number of the adjustment
channels corresponds to half the number of the available channels.
9. The method according to claim 8, wherein respective channel
spans between the upper and lower limit adjustment channels and
respective lower limit adjustment channel numbers associated with
each available channel, except for the reference channel, are stored
in an array and allocated with indexes, each index corresponding
to at least one of the available channels.
10. The method according to claim 9, wherein the channel span and
the lower limit adjustment channel number 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 limit adjustment channel number associated with the
index of the currently available channel.
11. The method according to claim 8, wherein the derived compensation
value is rounded off.
12. A method for compensating for transmission power deviations
of channels in a mobile phone having allocated available channels
selected from channels for mobile phone services, comprising the
steps of: selecting adjustment channels from the channels for mobile
phone services; selecting at least one reference channel from the
allocated available channels; deriving transmission automatic gain
control (AGC) level values for the adjustment channels and the at
least one reference channel; and deriving an offset value for each
adjustment channel consisting of a difference between the transmission
AGC level value of said adjustment channel and the transmission
AGC level value of the at least one reference channel.
13. The method as recited in claim 12, wherein only the at least
one reference channel is both an allocated available channel and
an adjustment channel.
14. The method according to claim 12, comprising the further step
of: deriving a compensation value for a currently available channel
of the allocated available channels.
15. The method according to claim 14, further comprising the steps
of: deriving a channel span between each adjustment channel and
an adjustment channel above each said adjustment channel.
16. The method as recited in claim 15, wherein the step of deriving
a compensation value consists of: finding a lower adjustment channel
below the currently available channel; finding an upper adjustment
channel above the currently available channel; finding the channel
span between the lower adjustment channel and an adjustment channel
above the lower adjustment channel; finding an offset span consisting
of a difference between the offset value of an upper adjustment
channel and the offset value of the lower adjustment channel; finding
a current channel span between the currently available channel and
the lower adjustment channel; and performing the following calculation:
##EQU5## where, "Lower Adjustment Channel" represents
the offset value of the lower adjustment channel.
17. The method as recited in claim 12, wherein the step of deriving
an offset value is performed each time the mobile phone is turned
on.
18. The method as recited in claim 17, wherein the derived offset
values are stored in a volatile memory.
19. The method as recited in claim 12, wherein the derived AGC
values are stored in a non-volatile memory.
20. The method as recited in claim 14, wherein the step of deriving
a compensation value is performed at predetermined time intervals.
21. The method as recited in claim 15, wherein the derived channel
spans are stored in a non-volatile memory.
22. The method as recited in claim 15, comprising the further steps
of: storing the derived transmission AGC level values in a non-volatile
memory; storing the derived offset values in a volatile memory;
setting an index value corresponding to each adjustment channel
and the channel span of said adjustment channel; and setting one
of said index values for each of the allocated available channels.
23. The method as recited in claim 22, wherein the step of deriving
a compensation value comprises the steps of: finding the index value
for said currently available channel, wherein the adjustment channel
corresponding to the index value is a lower adjustment channel;
finding an upper adjustment channel as an adjustment channel above
the lower adjustment channel; finding an offset span consisting
of a difference between the offset value of an upper adjustment
channel and the offset value of the lower adjustment channel; finding
a current channel span between the currently available channel and
the lower adjustment channel; and performing the following calculation:
##EQU6## where, "Lower Adjustment Channel" represents
the offset value of the lower adjustment channel.
Mobile Phone Patent Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mobile phone, and more particularly
to a method for minimizing transmission power deviations of channels
in a mobile phone.
2. Description of the Related Art
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.
Transmission power for each available channel in a mobile phone
should meet a specifically made standard tolerance. 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 the 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 may
exist for the same channel because those mobile phones have different
hardware characteristics. Transmission power variations among different
channels or transmission power differences among different phones
for the same channel are called "transmission power deviations
of channels". When the transmission power deviations of channels
is high, errors in transmission power such as generation of maximum
power or an open loop on a certain channel may occur.
In order to minimize such transmission power deviations of channels,
the manufacturer may conduct, for each phone manufactured, a measurement
of transmission power for each available channel while varying the
AGC level, and then adjust the transmission power for each available
channel to an optimal level, based on the measured transmission
power. In this case, transmission AGC levels corresponding to the
optimal transmission power are stored in a non-volatile memory and
they are used for available channels during a practical use of the
phone set. For the non-volatile memory, an electrically erasable
and programmable ROM (EEPROM) is typically used.
However, a lot of time is taken for the above mentioned method
in which transmission AGC levels are obtained by conducting, for
each phone, a measurement of transmission power for all available
channels, which are typically 20 in number, and then conducting
an adjustment of transmission power based on the measured transmission
power. Each transmission AGC level relevant to available channels
is stored in a non-volatile memory. As a result, the non-volatile
memory area in use increases according to the number of available
channels.
In order to reduce the above mentioned problem, a method is proposed
in which adjustment channels are used, the number of which is less
than the number of available channels. That is, optimum transmission
AGC level values are derived only for the adjustment channels, and
then stored in the non-volatile memory of the portable phone. Using
these stored AGC level values, the optimum transmission power of
available channels for a mobile hone may be determined when the
mobile phone is used in practice. The determination of optimum transmission
power is made only for the currently available channel, 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 of the phone hardware. Thus, the number of
channels for which certain processes are required in the process
of manufacturing mobile phones is reduced. These 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, when this method is used, it is necessary to accurately
and efficiently adjust or compensate for the transmission AGC levels
stored in the non-volatile memory for the currently available channel.
If not, high transmission power deviations of channels may result
in errors in transmission power in practical use even though the
problems involved in the manufacture of the mobile phone are eliminated.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a method for
minimizing transmission power deviations of channels. Another object
of the present invention is to provide a method for efficiently
compensating for transmission power deviations.
In accordance with 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 mobile phone service, while including a reference
channel allocated to the mobile phone from the channels for mobile
phone service, the number of adjustment channels being less than
the number of the allocated available channels, the mobile phone
including an 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
to an optimum level for each of the adjustment channels, comprising:
an offset value processing procedure for reading out the transmission
AGC level values from the non-volatile memory, and 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
a compensation value processing procedure for deriving a compensation
value for a currently available channel, based on the offset values
of adjustment channels located above and below the currently available
channel, the channel span between the currently available channel
and the adjustment channel located below it, and the channel span
between the adjustment channels located above and below the currently
available channel, while using the following expression: ##EQU1##
where "ch_pwr_offset" represents the compensation value,
"max_ch_offset" and "min_ch_offset" represent
the offset values of the adjustment channels located above and below
the currently available channel respectively; "span" represents
the channel span between the adjustment channel located above the
available channel and the adjustment channel located below the available
channel, "ch" represents the channel number of the currently
available channel, and "min_ch" represents the channel
number of the adjustment channel located below the available channel.
The adjustment channel above the currently available channel is
the "upper limit adjustment channel" and the adjustment
channel below is the "lower limit adjustment channel".
BRIEF DESCRIPTION OF THE DRAWINGS
The above objects and advantages of the present invention will
become more apparent by describing in detail a preferred embodiment
thereof with reference to the attached drawings in which:
FIG. 1 is a block diagram illustrating the configuration of a mobile
phone to which the present invention is applied;
FIG. 2 is a graph of the line used for a transmission AGC level
comparison among adjustment channels in accordance with the preferred
embodiment of the present invention;
FIG. 3 is a diagram illustrating a compensation value calculation
according to the preferred embodiment of the present invention;
FIG. 4 is a flow chart illustrating an offset value processing
procedure according to the preferred embodiment of the present invention;
and
FIG. 5 is a flow chart illustrating a compensation value processing
procedure according to the preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference will now be made in detail to the preferred embodiments
of the present invention. In the following description of the preferred
embodiment of the present invention, a variety of specific elements
such as the number of channels, channel numbers, 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 preferred embodiment 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 preferred embodiment will be described in conjunction with an
example in which it is applied to mobile phones of a CDMA system.
FIG. 1 is a block diagram illustrating the configuration of a mobile
phone to which the preferred embodiment of the present invention
is applied. Referring to FIG. 1, a control unit 100 is illustrated
which directs 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 FIG. 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 is stored with transmission
AGC levels and a variety of reference data. Programs for the processing
and control 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 numeral keys to apply a key input generated by the
user to the control unit 100. The display unit 110 is typically
provided with an LCD to display a variety of information in the
form of an image under the direction of the control unit 100. The
RF module 114 conducts transmission and reception of RF signals
with a base station over 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 over the antenna
112. The RF module 114 makes transmission power adjustments to the
signal to be transmitted.
The baseband processing unit 116 is a baseband analog (BBA) ASIC
providing an interface between the control unit 100 and the RF module
114. This baseband processing unit 116 converts 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 speech signals
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 adjustment channels to optimum levels. The number of the
adjustment channels is less than the number of available channels
associated with the mobile phone. In the preferred embodiment of
the present invention, 10 adjustment channels, the number of which
corresponds to half the number of available channels, that is, 20,
as mentioned above, are selected from AMPS channels. The transmission
AGC levels practically measured for the adjustment channels are
described in Table 1. Also, FIG. 2 is a graph of the line used for
a transmission AGC level comparison among the adjustment channels.
TABLE 1 Adjustment Channel No. Transmission AGC 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 the adjustment channel number 363,
are not available channels, that is, channels for voice or data
transmission by the mobile phone. Accordingly, the adjustment channel
No. 363 is used as the reference channel for conducting transmission
power compensation for the available channels.
Each of the available channels exists between two adjustment channels
in channel number. In this regard, the transmission AGC level of
an available channel can be derived from the transmission AGC levels
of the upper and lower limit adjustment channels, located above
and below, respectively, the available channel in channel number.
If the transmission AGC level difference between the currently available
channel and the reference channel is known, it is then possible
to make a 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. That is, the transmission AGC level difference
between the currently available channel and the reference channel
is a compensation value used to adjust the currently available channel
for the transmission power deviation. This compensation value may
be referred to as a "channel power offset value" because
it is an offset to the transmission AGC level of the reference channel.
When the currently available channel is the reference channel, it
is unnecessary to derive the compensation value because the transmission
AGC level of the reference channel is the same as that of the currently
available channel.
The offset value for each adjustment channel from the reference
channel, which corresponds to the transmission AGC level difference
between each adjustment channel and the reference channel, is described
in Table 2.
TABLE 2 Transmission AGC Level Adjustment Channel Value Offset
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
In order to appropriately compensate for transmission power deviations
of channels, it is necessary to accurately and efficiently derive
compensation values for the available channels. A method for deriving
compensation values in accordance with the preferred embodiment
of the present invention will now be described in conjunction with
FIG. 3. In FIG. 3, "ch" denotes the number of the currently
available channel for which a compensation value needs to be derived.
"max_ch" and "min_ch" represent upper and lower
limit adjustment channels located above and below respectively,
the currently available channel current_ch in channel number. "span"
represents the channel span between the upper and lower limit adjustment
channels max_ch and min_ch. For example, when the currently available
channel numbers is 193, it exists between the adjustment channel
numbers 120 and 240, as shown in Table 1. Accordingly, the upper
and lower limit adjustment channel numbers, 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 FIG. 3, "min_ch_offset" and "max_ch_offset"
represent the offset values of the upper and lower limit adjustment
channels from the reference channel, as described in Table 2. "ch_pwr_offset"
is the channel power offset value and represents the compensation
value used for compensating for a transmission power deviation of
the currently available channel.
As shown in FIG. 3, the compensation value ch_pwr_offset can be
expressed by a general linear equation, that is, "y=mx+b"
(where, "m" represents the slope, and "b" represents
the offset value of the lower limit adjustment channel). Accordingly,
the compensation value ch_pwr_offset can be derived from the following
Expression 1: ##EQU2##
From the compensation value derived using the upper and lower limit
adjustment channel numbers associated with the currently available
channel along with the respective offset values for those 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 the 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, adjustment channel
number 363. The derived transmission AGC levels of the 20 available
channels are depicted by the line on the graph shown in FIG. 2.
Since transmission power deviations of channels can be accurately
and efficiently adjusted using the above mentioned method, it is
possible to store the measured transmission AGC levels of only 10
adjustment channels, half the number of available channels, in the
EEPROM 102. Accordingly, it is possible to minimize transmission
power deviations of channels while simplifying and reducing the
processes conducted by the manufacturer.
In order to derive the compensation value ch_pwr_offset using Expression
1, it is necessary to first derive the lower limit adjustment channel
number, min_ch, and the channel span, span. The values are derived
at the manufacturing end through an appropriate calculation. The
derived values can be arranged in an appropriate table where indexes
correspond to each lower limit adjustment channel and its respective
channel span. An example of such a table is Table 3. Table 3 shows
the index values with their respective lower limit adjustment channel
numbers, min_ch, and respective indexed channel spans, span, as
well as the 20 available channels associated with the index values.
TABLE 3 Available Channel Index Min_ch Span 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, adjustment channel 363 has no index because it is the
reference channel, thus it requires no compensation. Furthermore,
the span of channel 991 is 33 because channel 1 is equivalent to
1024. When it is desired to derive a compensation value for a currently
available channel in a mobile phone, this can be simply achieved
using such a table in which the lower limit adjustment channel numbers,
min_ch, and channel spans, span, are arranged while being allocated
with indexes in such a fashion that each available channel corresponds
to one index. Thus, if only the index of the currently available
channel is derived, min_ch and span can be found in an array corresponding
to Table 3. Accordingly, it is not necessary to perform a separate
calculation in order to find min_ch and span, when these values
are needed to perform the calculation shown in Expression 1.
An example of an array for lower limit adjustment channel numbers,
min_ch, is as follows:
An example of an array for channel spans, span, is as follows:
The constants min_ch and span are included in the program of the
controller 100, as shown below in regards to FIG. 5, as arrays and
the program is stored in the flash memory 104.
Now, the method of compensating for transmission power deviations
of channels in accordance with the preferred embodiment of the present
invention will be described in conjunction with FIG. 4, which illustrates
an offset value processing procedure, along with FIG. 5, which illustrates
a compensation value processing procedure.
The offset value processing procedure shown in FIG. 4 is conducted
by the controller 100 every time the mobile phone of FIG. 1 turns
on. On the other hand, the compensation value processing procedure
shown in FIG. 5 is periodically conducted at predetermined time
intervals. For example, the compensation value processing interval
can be set to coincide with the transmission power adjustment processing
interval. In this case, the compensation value processing interval
is set by 1.25 ms, because the base stations of the current CDMA
system conduct transmission power adjustment processing intervals
of 1.25 ms. In the offset value processing procedure of FIG. 4,
which is conducted every time the mobile phone turns on, the offset
values are calculated and stored in the RAM 106, where they will
be kept unless the mobile phone turns off.
First, the offset value processing procedure will be described
in conjunction with FIG. 4. When the mobile phone turns on, the
control unit 100 reads the transmission AGC level values, as described
in Table 1, the adjustment channels from the EEPROM 102 at step
200, as shown in FIG. 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 the adjustment channels, as described in Table 2, are then also
stored in the form of an array in the RAM 106. Next, the number
of the reference channel, in this case, 363, is stored as the 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 FIG. 5, which
is conducted at predetermined time intervals.
In accordance with the compensation value processing procedure
of FIG. 5, the controller 100 stores the number of the currently
available channel as a parameter current_ch 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, namely, the
number of the currently available channel, is 363. If the currently
available channel number current_ch is 363, it is unnecessary to
conduct any transmission power consumption because the currently
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 currently available channel, at step 318. Thereafter,
the procedure returns to a normal routine. On the other hand, if
it is determined at step 302 that the currently available channel
number current_ch does not correspond to 363, the procedure proceeds
to step 304. At step 304, it is checked whether or not the currently
available channel number current_ch, equals the parameter old_ch.
If the current available channel number, current_ch, equals the
parameter old_ch, the previous compensation value can be 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,
if it is determined at step 304 that the current available channel
number, current_ch, does not equal the parameter old_ch, steps 306
to 316 are executed in order to derive a new compensation value.
At step 306, the currently available channel number, current_ch,
is stored as the parameter old_ch. That is, the parameter old_ch
is updated with the currently available channel number, current_ch.
At step 308, the index for the currently available channel number,
current_ch, is then derived. The index value is programmed to be
calculated by the available channel numbers, and included in the
program of the controller 100 shown in FIG. 1. Using the derived
index, the above mentioned array is then searched for the channel
span, span, and lower limit adjustment channel number, min_ch, associated
with the current available channel step 310.
Thereafter, max_ch_offset and min_ch_offset (respectively corresponding
to max_ch and min_ch) are retrieved from among the offset values
stored in RAM 106. Then, the channel power offset value, which is
the compensation value for the currently available channel, is calculated
at step 312, based on the derived channel span, span, lower limit
adjustment channel number, min_ch, and offset values min_ch_offset
and max_ch_offset using Expression 1. The calculated channel power
offset value can be calculated to several decimals. In the preferred
embodiment, these decimal values are used in rounding off the channel
power offset value, in step 314. This use of the decimal values
results in the enhanced accuracy of the channel power offset value.
This rounded-off channel power offset value is stored at step 316
so that it can be used for 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 currently available
channel with the adjustment channels above and below the currently
available channel and the respective transmission AGC level differences
of those adjustment channels from the reference channel. Using this
comparison value, it is possible to obtain an accurate transmission
AGC level of the currently available channel that meets the characteristics
of the current available channel. This makes it possible to store
only the measured transmission AGC levels of the adjustment channels,
the number of which corresponds to half the number of available
channels, in an EEPROM. Accordingly, it is possible to minimize
the transmission power deviations of channels while simplifying
and reducing the processes conducted by the manufacturer.
As apparent from the above description, the preferred embodiment
of 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 currently
available channel by use of the upper and lower limit adjustment
channel numbers associated with the currently available channel
along with respective offset values for the upper and lower limit
adjustment channels, thereby minimizing and efficiently compensating
for the transmission power deviation of the currently 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 predetermined time intervals,
and the offset value processing procedure has been described as
being conducted only when the mobile phone turns on, the present
invention is not limited to such conditions. Other conditions for
those procedures may be used as long as the offset value processing
procedure is conducted prior to the compensation value processing
procedure. In the preferred embodiment, the processing step for
determining whether or not a channel change is made and the processing
step for determining whether or not the currently available channel
is the reference channel are conducted in order to reduce the amount
of calculation required. However, these processing steps may be
eliminated. In addition, although the number of adjustment channels
in the preferred embodiment equals half the number of available
channels, the present invention is not limited to that ratio of
adjustment channels to available channels.
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