Symbol combining method for reducing the number of FIFO registers of finger, rake receiver and method for driving the rake receiver
View Patent ↗A symbol combining method in a Rake receiver, which relates to a method for combining the demodulated multi-path signals in a demodulation process of a code division multiple access communication system. The symbol combining method, a Rake receiver using the symbol combining method and a method for driving the Rake receiver, remarkably reduce a hardware complexity of a FIFO register used to regulate a timing synchronization of each finger in Rake receiver by using a new algorithm in a combining process when a CDMA communication system combines a plurality of multi-path signals therebetween. Whereas a conventional combining algorithm uses an individual FIFO register every finger so as to adjust a timing synchronization of each symbol before combining a demodulated symbol, the inventive combining algorithm performs a symbol combining operation as well as a timing synchronization of a symbol at the same time, and performs a combining action by using only one FIFO register irrespective of the number of fingers.
1. A Rake receiver for performing a symbol combining function with respect to demodulated multi-path signals in a demodulation step of a code division multiple access(CDMA) communication system, comprising only one FIFO(First-In First Out) register that accumulates a plurality of previously-stored FIFO register values by using an adding part and then stores the accumulated value in the FIFO register when storing a finger-demodulated symbol in the FIFO register, and further including a control logic part that determines a block position of the FIFO register where a transmitted symbol demodulated in each finger is to be stored and outputs a combined symbol data after receiving an output signal, and wherein the control logic part includes a circuit for calculating a writing position of the FIFO register by using a phase of a PN code, a symbol duration, and a depth of the FIFO register.
2. The Rake receiver according to claim 1 , wherein the control logic part includes a part that sequentially selects a symbol data of each finger to be combined by using a writing signal and a symbol duration that are received from each finger.
3. The Rake receiver according to claim 1 , wherein the circuit determines a writing position of the FIFO register by using the following equation:
W
=
(
⌊
P
S
⌋
-
1
)
mod
N
where, [x] is a maximum integer below ‘x’, x mod y(modulo-operation) is a remainder when ‘x’ is divided by ‘y’, W is a variable indicating a storage position of a selected symbol data, P is a variable indicating a timing reference of each symbol by using a phase of PN code, S is a variable indicating a symbol duration, and N is a depth of the FIFO register.
4. The Rake receiver according to claim 1 , further comprising:
a combiner for combining a symbol data demodulated in each finger with an output value of the FIFO register.
5. A method of combining a symbol of demodulated multi-path signals in a demodulation step of a CDMA communication system, comprising the steps of:
accumulating a plurality of previously-stored FIFO register values by using an adding part and then storing the accumulated values in the FIFO register when storing a finger-demodulated symbol in the FIFO register; and
calculating a writing position of the FIFO register by using a phase of a PN code, a symbol duration, and a depth of the FIFO register.
6. The symbol combining method according to claim 5 , further comprising the step of:
sequentially selecting a symbol data of each finger to be combined by using a writing signal and the symbol duration that are received from each finger.
7. The symbol combining method according to claim 5 , further comprising the step of:
determining a writing position of the FIFO register by using following equation:
W
=
(
⌊
P
S
⌋
-
1
)
mod
N
where, [x] is a maximum integer below ‘x’, x mod y(modulo-operation) is a remainder when ‘x’ is divided by ‘y’, W is a variable indicating a storage position of a selected symbol data, P is a variable indicating a timing reference of each symbol by using a phase of PN code, S is a variable indicating the symbol duration, and N is a depth of the FIFO register.
8. The symbol combining method according to claim 5 , further comprising the step of:
combining a symbol data demodulated in each finger with an output value of the FIFO register.
9. A symbol combining method for driving a Rake receiver that includes only one FIFO register, comprising:
accumulating a plurality of previously-stored FIFO register values by using an adding part and then storing the accumulated value in the FIFO register when storing a finger-demodulated symbol in the FIFO register;
when storing data in the FIFO register after finishing a processing of the symbol data in an i-th finger, selecting a symbol data and a pseudo noise(PN) phase of the i-th finger;
calculating a writing position of indicating a block of the register where the symbol data is stored by using a selected PN code phase; and
reading the data of the block located at the calculated writing position, combining the read block data with the symbol data to be stored, and storing a resultant value into the block located at the calculated writing position,
wherein the step of calculating a writing position by using a selected PN code phase comprises determining the writing position of the FIFO register by using the following equation:
W
=
(
⌊
P
S
⌋
-
1
)
mod
N
where, [x] is a maximum integer below ‘x’, x mod y (modulo-operation) is a remainder when ‘x’ is divided by ‘y’, W is a variable indicating a storage position of a selected symbol data, P is a variable indicating a timing reference of each symbol by using a phase of the PN code, S is a variable indicating the symbol duration, and N is a depth of the FIFO register.
10. The symbol combining method for driving Rake receiver according to claim 9 , further comprising the step of:
if at least two fingers ask a storage action at the same time, firstly processing a finger of a low number prior to a finger of a high number, and then processing the finger of a high number.
11. A symbol combining method for driving a Rake receiver having only one FIFO register, comprising:
accumulating a plurality of previously-stored FIFO register values by using an adding part and then storing the accumulated value in the FIFO register when storing a finger-demodulated symbol in the FIFO register;
a) when storing data in the FIFO register after finishing a processing of the symbol data in an i-th finger, selecting a symbol data and a pseudo noise(PN) phase of the i-th finger;
b) calculating a writing position indicating a block of the register where the symbol data is stored by using the selected PN code phase;
c) reading the data of the block located at the calculated writing position, combining the read block data with the symbol data to be stored, and storing a resultant value into the block positioned at the calculated writing position;
d) repeating steps (a), (b) and (c);
e) upon generation of a reading signal, calculating a block position of the FIFO register to be read; and
f) selecting data located at the calculated block position of the FIFO register in step(e), transmitting the selected data to a combiner, and then initializing the register.
12. The symbol combining method for driving Rake receiver according to claim 11 , further comprising the step of:
if at least two fingers ask a storage action at the same time, firstly processing a finger of a low number prior to a finger of a high number, and then processing the finger of a high number.
13. The symbol combining method for a driving Rake receiver according to claim 11 , wherein the step for calculating a writing position by using a selected PN code phase determines a writing position of the FIFO register by using the following equation:
W
=
(
⌊
P
S
⌋
-
1
)
mod
N
where, [x] is a maximum integer below ‘x’, x mod y (modulo-operation) is a remainder when ‘x’ is divided by ‘y’, W is a variable indicating a storage position of a selected symbol data, P is a variable indicating a timing reference of each symbol by using a phase of the PN code, S is a variable indicating a symbol duration, and N is a depth of the FIFO register.
14. A computer-readable storage medium, comprising the storage of a program for executing a symbol combining demodulated multi-path signals in a demodulation step of a CDMA communication system, wherein the program executes the steps of:
accumulating a plurality of previously-stored FIFO register values by using an adding part;
storing the accumulated value in the FIFO register; when storing a finger-demodulated symbol in the FIFO register; and
determining a block position of the FIFO register where the transmitted symbol demodulated in each finger is to be stored, and outputs a combined symbol data after receiving an output signal;
wherein the determining step includes a sub-step for calculating a writing position of the FIFO register by using a phase of a PN code, a symbol duration, and a depth of FIFO register.
15. A computer-readable storage medium recording a program for executing a symbol combining method for driving a Rake receiver that includes only one FIFO register, and accumulates a plurality of previously-stored FIFO register values by using an adding part, and then stores the accumulated value in the FIFO register when storing a finger-demodulated symbol in the FIFO register, comprising the steps of:
when storing data in the FIFO register after finishing a processing of the symbol data in an i-th finger, selecting a symbol data and a pseudo noise(PN) phase of the i-th finger;
calculating a writing position indicating a block of the register where the symbol data is stored, by using the selected PN code phase; and
reading the data of the block located at the calculated writing position, combining the read block data with the symbol data to be stored, and storing a resultant value into the block located at the calculated writing position,
wherein the step for calculating a writing position by using a selected PN code phase determines a writing position of the FIFO register by using the following equation:
W
=
(
⌊
P
S
⌋
-
1
)
mod
N
where, [x] is a maximum integer below ‘x’, x mod y (modulo-operation) is a remainder when ‘x’ is divided by ‘y’, W is a variable indicating a storage position of a selected symbol data, P is a variable indicating a timing reference of each symbol by using a phase of the PN code, S is a variable indicating a symbol duration, and N is a depth of the FIFO register.
16. A computer-readable storage medium, comprising:
a program stored in the medium for executing a symbol combining method for driving a Rake receiver that includes only one FIFO register, accumulates a plurality of previously-stored FIFO register values by using an adding part, and then stores the accumulated value in the FIFO register when storing a finger-demodulated symbol in the FIFO register, the program executing the steps of: a1) when storing data in the FIFO register after finishing a processing of the symbol data in an i-th finger, selecting a symbol data and a pseudo noise(PN) phase of the i-th finger;
b1) calculating a writing position indicating a block of the register where the symbol data is stored by using the selected PN code phase;
c1) reading the data of the block located at the calculated writing position, combining the read block data with the symbol data to be stored, and storing a resultant value into the block located at the calculated writing position.
d1) repeating steps (a1), (b1) and (c1);
e1) upon generation of a reading signal, calculating a block position of the FIFO register to be read; and
f1) selecting data located at the calculated block position of the FIFO register in step(e1), transmitting the selected data to a combiner, and then initializing the block.