EP1155511A1 - Procede et appareil permettant de selectionner un symbole variable de maniere adaptative - Google Patents

Procede et appareil permettant de selectionner un symbole variable de maniere adaptative

Info

Publication number
EP1155511A1
EP1155511A1 EP00989429A EP00989429A EP1155511A1 EP 1155511 A1 EP1155511 A1 EP 1155511A1 EP 00989429 A EP00989429 A EP 00989429A EP 00989429 A EP00989429 A EP 00989429A EP 1155511 A1 EP1155511 A1 EP 1155511A1
Authority
EP
European Patent Office
Prior art keywords
signal
bits
location
communication device
present
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00989429A
Other languages
German (de)
English (en)
Inventor
Luis Aldaz
Daniel Jeng Hsia
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NXP BV
Original Assignee
Koninklijke Philips Electronics NV
Philips Semiconductors Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US09/677,938 external-priority patent/US6754503B1/en
Application filed by Koninklijke Philips Electronics NV, Philips Semiconductors Inc filed Critical Koninklijke Philips Electronics NV
Publication of EP1155511A1 publication Critical patent/EP1155511A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/204—Multiple access
    • H04B7/216—Code division or spread-spectrum multiple access [CDMA, SSMA]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/06—Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection
    • H04L25/067—Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection providing soft decisions, i.e. decisions together with an estimate of reliability
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H04B1/7097—Interference-related aspects
    • H04B1/711—Interference-related aspects the interference being multi-path interference
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2201/00—Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
    • H04B2201/69—Orthogonal indexing scheme relating to spread spectrum techniques in general
    • H04B2201/707—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
    • H04B2201/70707—Efficiency-related aspects

Definitions

  • the present disclosure relates to the field of digital communications. Specifically, the present disclosure relates to an apparatus and a method for adaptively selecting a soft symbol for a subsequent operation, e.g., decoding, within a communication device. The present disclosure describes a method for adaptively selecting a soft symbol for a subsequent operation a communication device.
  • Wireless communication is expanding to all forms of devices that use information, e.g. cellular phones, a networks, personal digital assistants (PDAs), digital cameras, etc.
  • PDAs personal digital assistants
  • CDMA Code Division Multiple Access
  • CDMA spread spectrum format is among the most commonly deployed wireless technology. Because of increasing demand and limited resources, a need arises to improve their fidelity and performance of wireless communication devices and systems.
  • a conventional base station 104 e.g. cell
  • a mobile unit 102 e.g. a cell phone
  • a CDMA system uses a common bandwidth to transmit the pilot signal and a data signal 106 between a base station 104 and a mobile unit 102, for multiple users.
  • the bandwidth is occupied by an combination of many signals.
  • the original signal can take multiple paths to arrive at a destination device with various forms of delay and phase shift. These signals from the different paths are referred to as multipath signals. Because the multipath signals can vary substantially in signal strength and other performance factors, a need arises for a method to appropriately evaluate received signals for processing into meaningful data, e.g., voice data.
  • One conventional configuration identifies only a fixed location, or portion, of bits of the combined signal for subsequent decoding.
  • the fixed location of bits from the combined signal is chosen for its overall performance in many different signal-reception scenarios.
  • this prior art configuration typically yields only nominal performance in each of the wide-range of reception scenarios.
  • this fixed portion of the combined signal is typically identified in a design phase of the hardware and software, and then programmed into the phone. Hence, a phone may be limited during its entire life to the fixed portion of the combined signal. Consequently, a need arises for a method that overcomes the prior art limitations of selecting a fixed location of bits from the combined signal for decoding.
  • a need arises to improve their fidelity and performance of wireless communication devices and systems. Furthermore, a need arises for a method to appropriately evaluate received signals for processing into meaningful data, e.g., voice data. Finally, a need arises for a method that overcomes the prior art limitations associated with selecting a fixed location of bits from the combined signal for decoding.
  • the present disclosure describes a method and apparatus for improving the fidelity and performance of digital communication devices and systems, in particular, the present disclosure describes a method to appropriately evaluate received signals for processing into meaningful data, e.g., voice data. Finally, the present disclosure describes a method that overcomes the prior art limitations associated with selecting a fixed location of bits from the combined signal for a subsequent operation.
  • one disclosed embodiment provides a method of adaptively selecting a soft symbol for a subsequent operation in a communication device.
  • a signal is received at the communication device.
  • the signal is demodulated.
  • a strength level such as a signal to noise ratio Eb/Nt
  • Eb/Nt is the ratio of combined energy per bit to the effective noise power spectral density, which is known by those skilled in the art.
  • the aforementioned method is implemented in a communication device having a processor, e.g., a general purpose processor, a memory, a rake receiver, and a digital signal processor (DSP).
  • the memory portion of the communication device contains data and program instructions that, when executed via the processors, implement the aforementioned method for adaptively selecting a soft symbol from the composite signal for a subsequent operation in the communication device.
  • This bit selection process provides very little head room. This scheme forces higher resolution in the area around the origin, and saturates large signal amplitudes. The process is viable because, at large amplitudes, the signal is unlikely to be decoded incorrectly, and thus does not require much resolution at these signal amplitudes.
  • FIGURE 1 is an illustration of a conventional base station and cell phone.
  • FIGURE 2A is a functional block diagram of a bit-selection process, in the context of other communication operations, performed on a signal in accordance with one embodiment of the present invention.
  • FIGURE 2B is a detailed functional block diagram of a bit selection engine, in accordance with one embodiment of the present invention.
  • FIGURE 2C is a detailed functional block diagram of a pre-processing function, in accordance with one embodiment of the present invention.
  • FIGURE 2D is a detailed functional block diagram of a post-processing function, in accordance with one embodiment of the present invention.
  • FIGURE 3 is a hardware block diagram of a communication device used for the bit- selection process, in accordance with one disclosed embodiment.
  • FIGURE 4 is a graph of several exemplary cases of signal performances, and their corresponding influence on bits of the combined signal, in accordance with one disclosed embodiment.
  • FIGURE 5 is a flow diagram of the steps used to implement a method for adaptively selecting a soft symbol for a subsequent operation e.g., a decoding operation, within a communication device, in accordance with one disclosed embodiment.
  • the data is represented as physical (electronic) quantities within the communication devices components, or the computer system's registers and memories, and is transformed into other data similarly represented as physical quantities within the communication device components, or computer system memories or registers, or other such information storage, transmission or display devices.
  • a communication device such as a base station 104
  • a signal 240 which can include a pilot signal and/or a data signal.
  • Data signal is processed by a communication device, such as a cell phone, whose functions are represented by the function blocks shown in Figure 2A.
  • the functions shown can be implemented by a wide range of communication devices, including base stations, personal computers (PCs), digital cameras, and any other device that has the capability of wireless communication.
  • the present invention is also well suited to the wide range of products being developed for the Blue Tooth specification of wireless communication.
  • the communication device performs a demodulation function 242 on the signal.
  • the demodulation function is performed for each of multiple possible multipath signals 242a, if applicable for a given application.
  • the channel estimator function block 244 which is functionally coupled to demodulation block 242, estimates the strength of a signal, e.g., for each of the multipath signals that was demodulated.
  • Channel estimator function 244 can determine a signal strength, such as a signal to strength ratio Eb/Nt which is well- known by those skilled in the art. However, the present invention is well suited to determining any other type of signal strength indicator.
  • Eb refers to the received energy per bit for the desired signal in Watt-seconds
  • Nt is the received energy per bit for the noise within the signal.
  • a combiner function block 246 of Figure 2A which is functionally coupled to demodulation block 242, adds the multipath signals to provide a composite signal 246a.
  • Composite signal 246a is a 24 bit 2's complement number in the present embodiment, though the present invention is suitable for using any configuration of signal.
  • Combiner function 246 can be managed by other algorithms and management systems.
  • the pre-processing function prepares composite signal 246a for the bit-selection function block. More detail on pre-processor function block 248 is provided in subsequent Figure 2C.
  • bit selection block 250 which is functionally coupled to pre-processor block 248 and to channel estimator block 244 adaptively selects, or isolates, the appropriate number of bits of a signal for a subsequent operation.
  • bit selection block 250 selects only a six bit portion of the formatted composite signal for a subsequent demodulation operation. This six bit number is commonly referred to as a "soft symbol" 250a.
  • the present invention is well suited to choosing any bit-length portion of a signal, as appropriate for a given application.
  • the specific six bit portion of a signal chosen at one point in time may be different than the specific six bit portion of the signal chosen at a different point in time, e.g., on the same communication device.
  • the present invention provides an adaptive bit-selection function. This feature overcomes the limitation associated with the prior art, which fixes the soft symbol at a static location of bits within the composite signal.
  • Figure 2B provides exemplary criteria used to decide which portion of the signal to use.
  • a post processor function block 254 which is functionally coupled to bit selection block 250, performs a post-processing function. Post-processing function 254 prepares a soft symbol signal 250a for the demodulation function. More detail on post-processor function block 254 is provided in subsequent Figure 2D.
  • a decode function block 256 which is functionally coupled to post processor block 254, performs a decoding function.
  • Decoding function 256 can be performed using any of several methods that are well-known to those skilled in the art.
  • One such decoder is a Viterbi decoder, used in code division multiple access (CDMA) systems. While the present invention adaptively provides a soft symbol to a decoding operation, the present invention is well suited to providing a soft symbol, or some other bit sequence, for some other type of operation within the communication device.
  • Bit selection engine 250 receives a number of criteria at an interface 249. These criteria will be used to decide which bits of a signal to select for subsequent processing, e.g., decoding.
  • the criteria includes signal strength criteria 260, temporal performance 262, and performance pattern 264.
  • Subsequent Figure 4 provides examples as to the effect these criteria may have on the bit selection process.
  • the present invention is well suited to using any combination of these criteria, or to using other types of criteria that would allow it to adaptively select a desired number of bits from a signal for any one of multiple subsequent operations.
  • bit location value 260 can have a number of different configurations, depending upon the application.
  • bit location value 260 can be a scaling value that, when multiplied by the composite signal 248a via scaling block 251 , isolates the appropriate bit range, e.g., multiply a signal by a value of less than one to reduce the size, or number of bits, of the composite number.
  • the bit location value 260 can be an offset value which indicates the number of bits to be dropped from the LSB portion of the composite signal.
  • any type or method of corresponding data can be used, e.g., flags, etc.
  • the present invention is well suited to employing a prioritization scheme amongst the multiple criteria used for the bit-selection function. That is, one of the criteria may be given more weight than other factors, e.g., if it has a greater influence on the effects of the signal in a subsequent operation such as the decoder.
  • Pre-processing can include a wide variety of sub-functions.
  • composite signal 246a is processed through the following sub-functions: a) pass-through filter function 271 ; and b) format function 272.
  • pre-processor function block 248 can be configured to provide more or fewer sub-functions, as appropriate for a given application.
  • the format function in the present embodiment, drops 1 or more of the least significant bits (LSB). In the present embodiment, the eight LSBs of the 24 bit composite signal are dropped.
  • no pre-processor function is used.
  • the pre-processor function block 248 thus provides a formatted signal 248a.
  • Post-processing can include a wide variety of sub-functions.
  • soft symbol signal 250a is processed through the following sub-functions: a) pass-through filter function 276; b) format function 278; c) fixed point to double point conversion 280, (a.k.a. deinterleaver, depuncture, derepeat, and round up to a six-bit number); and d) z-transform (a.k.a. a delay operator) 282.
  • the format function in the present embodiment, drops the non- integer portion of the signal, thus providing a whole number portion of the signal.
  • post-processor function block 254 can be configured to provide a different quantity or type of sub-functions, as appropriate for a given application. Furthermore, in another embodiment, no post-processor function is used. Post- processor function block 250 thus provides a formatted soft symbol 254a. This bit selection process provides very little head room. Furthermore, it saturates large signal amplitudes. The process is viable because, at large amplitudes, the signal is unlikely to be decoded incorrectly, and thus does not require much resolution at these signal amplitudes. This scheme forces higher resolution in the area around the origin, and saturates large signal amplitudes.
  • Communication device 300 of Figure 3 can be a stand alone unit, such as a cellular phone. However, it may also be a component of a larger device, such as a printer, computer, cameras, personal digital assistant (PDA), etc. It is appreciated that the present invention is applicable to any device capable of processing wireless data of the appropriate configuration.
  • PDA personal digital assistant
  • Communication device 300c includes a firmware/software block 310 and an application specific integrated circuit (ASIC) block 320, coupled to each other.
  • ASIC block 320 includes an antennae 303, a transceiver 304, and a rake receiver 326.
  • Antennae 303 is coupled to transceiver 304 which in turn is coupled to rake receiver 326.
  • Rake receiver 326 in the present embodiment, includes three separate fingers, finger 1 321 , finger 2 322, and finger 3 323. Each finger demodulates an individually assigned multipath signal.
  • Firmware/software block 310 includes a processor 314 (e.g., a general purpose processor), memory 316, and a digital signal processor (DSP) 317, coupled to each other via bus 302.
  • Data and/or program instructions can be stored in memory 316 and implemented via processor 314 or DSP 317, in concern with other components of communication device 300, including those not shown that are well-known in the art.
  • Memory 316 of the present embodiment can include both permanent memory, such as read only memory (ROM), and temporary memory such as random access memory (RAM).
  • ROM memory can be utilized to store data for permanent functions of the dedicated service module, while RAM memory can be utilized to store data related to the on-site media service data.
  • Memory 316 can include other types of memory storage, capable of containing data, such as a hard drive, a CD ROM, or flash memory. In lieu of using memory to store instructions, a state machine can be designed to perform the desired instructions.
  • the present embodiment shows three fingers, the present invention is well-suited to using any number of fingers in a rake receiver. Additionally, the present invention can include more or less components than those shown in the present embodiment of communication device 300.
  • Communication device 300 can be used to implement the functions blocks of Figures 2A and 2B.
  • the demodulator function 242 can be accomplished by transceiver 304 and rake receiver 326 portions of ASIC 320.
  • the demodulation function can be accomplished by the firmware/software portion 310 of communication device.
  • pre-process function 248, bit selection function 250, and post-process function 254 are implemented via firmware/software 310 portion of communication device 300. However, they can also be implemented in an ASIC design.
  • FIG. 4 a graph of several exemplary cases of signal performances, and their corresponding influence on bits of the combined signal is shown, in accordance with one embodiment of the present invention.
  • Graph 400 will be described first, then composite signal 246a will be discussed, and finally, the interaction between these two entities will be described.
  • Graph 400 has an ordinate of signal amplitude 402 and an abscissa of time
  • Signal amplitude can represent signal power, or signal power to noise ratio, such as Eb/Nt.
  • Three cases of signal performances are shown in Figure 4. Each case has three separate multipath signals, e.g., one signal for each of three finger demodulators as shown in Figure 3.
  • Case 1 411 of Figure 4 is a grouping of three signals, all having a large amplitude 408. This indicates a strong, direct path of signal from one communication device to another.
  • Case 2 412 is a grouping of three signals, all having a small amplitude 410. This is an indication of a weak signal or an extended distance between communication devices.
  • case 3 413 is a grouping of three signals, two of them at a large amplitude 408 and one fading signal 413a that is degrading from a large amplitude 408 to a small amplitude over a period of time.
  • Composite signal 246a is a digital binary number that represents the strength of the added multipath signals.
  • composite signal is comprised of twenty-four (24) bits, though signal may have any length of bits.
  • the most significant bit (MSB) is located on the far left of the string of digits.
  • the least significant bit (LSB) is located on the far right of the string of digits.
  • the decimal point may be placed anywhere within the string of digits to create a real number. For case 1 411 , the large amplitude 408 and the small variation of each signal over time means that most of the changes in the composite signal 246a will be in bits closer to the MSB 440.
  • soft symbol 1 451 of six bits would be a more appropriate indication of the change in the signal amplitude for case 1 411.
  • the change in the signal is what provides the meaningful variations in an output signal that, for example, are words or other data. That is, a zero change in a signal is equivalent to a single tone which represents essentially negligible data.
  • the small amplitude 410 and small variation of each signal over time means that most of the changes in the composite signal will be in bits closer to the LSB 442.
  • soft symbol 2 452 of six bits would be a more appropriate indication of the change in the signal amplitude for case 2 412.
  • the large amplitude performance of two of the signals means that most of the significant changes in the signal will be in bits closer to the MSB 440, but the fading strength of signal 413a may temper the location of the soft symbol slightly in the direction of the LSB 442.
  • the specific choice of the bits can be dependent upon the specific scenario, the specific signal specifications, the specific application, and the specific level of simulation or analysis used to evaluate the scenario. The present invention is well suited to accommodating all these specific situations to provide a wide range of configurations or processes used to adaptively select a portion of bits from a signal for a subsequent operation.
  • FIGURE 5 is a flowchart 5000 of the steps used to implement the method for adaptively selecting a soft symbol for a subsequent decoding operation within a communication device, in accordance with one embodiment of the present invention.
  • Flowchart 5000 can be implemented via the functional blocks of Figures 2A or 2B and the hardware block diagram of Figure 3. The result of implementing flowchart 5000 is illustrated by the exemplary signal cases of Figure 4.
  • Flowchart 5000 begins with step 5002.
  • a signal is received.
  • Step 5002 can be implemented by antennae 303.
  • a signal can be received by any other wireless means such as satellite dish, etc.
  • flowchart 5000 proceeds to step 5003.
  • step 5003 of the present embodiment the signal is demodulated.
  • step 5003 is implemented, in one embodiment, using demodulate function block 242 of Figure 2A or using transceiver 304 and rake receiver 326 of Figure 3. Demodulation allows the data signal to be captured from the carrier signal. Following step 5003, flowchart 5000 proceeds to step 5004.
  • a strength level of the signal is determined.
  • the strength level can be a simple strength level, or a signal to noise ratio 5004a, such as Eb/Nt.
  • a variable can be used to track the performance of the signal over a period of time 5004b, e.g., by providing an averaged signal strength over a period of time.
  • Step 5004 can be implemented by channel estimator function 244 which itself can be implemented in firmware/software block 310 of Figure 3. Following step 5004, flowchart 5000 proceeds to step 5006.
  • step 5006 of the present embodiment the multipath versions of the signal, which have each gone through the previous steps, are combined to form a composite signal.
  • Step 5006 can be implemented by combiner function block 246 of Figure 2A, which itself can be implemented by firmware/software block 310 of Figure 3.
  • flowchart 5000 proceeds to step 5008.
  • a location of bits is chosen for the soft symbol.
  • the soft symbol is a consecutive six bit sequence from the composite signal that can be evaluated by a decoder.
  • the location of bits desired can be isolated from the composite signal by a number of methods, such as using a scaling function or by reformatting the signal.
  • Step 5008 can be implemented using bit selection function 250 of Figures 2A and 2B.
  • the present invention is well suited to using a wide variety of methods to choose a desired location of bits for the soft symbol depending upon the performance of the individual multipath signals and/or the composite signal.
  • flowchart 5000 proceeds to step 5010.
  • step 5010 of the present embodiment the performance the signal, and the respective location of bits chosen for the soft symbol, are adaptively updated.
  • Step 5010 can be implemented according to a timing schedule that is appropriate for a given device.
  • the adaptive updating can be performed based on the system cycle, or some other similar criteria.
  • the updating is performed on non-continuos signal values, e.g., one signal sample for every 125 millisecond cycle.
  • a given location of bits is set as the default value, either for initial system operation or for a consistent performance history. Thereafter, the location of bits can be changed for a changing environment, e.g., when the performance of the signal changes beyond a threshold.
  • the present invention is well suited to a wide variety of management techniques for deciding when and how the bit location should be changed.
  • Table 1 provides FER simulation results using the bit selection process of the present invention.
  • the HDS attributes define the real and fractional portion of the composite signal used for the Viterbi decoder.
  • the scaling indicates how the composite signal was scaled down from its initial 24 bit length.
  • the Floating and TR45 columns represent the floating point conversion of the number.
  • the row above the cases, in the left-most column indicate the K value of the signal, e.g., 1.2K is a 1200 cycle system.
  • the cases for different signal reception patterns is indicated below the system cycle case. For example, 1 finger fading has a 9.6 dB signal to noise ratio, Eb/Nt. This is a moderate case of fading.
  • the percentage values listed under each of the columns indicates the effectiveness of the bit selection process. Overall, this table shows the effectiveness of choosing a different location of bits for the decoding operation. Table 1
  • the present invention provides a communication device with greater flexibility. This flexibility allows the communication device to accommodate changing environments, which can be significant for mobile communication devices. Thereby, the present invention provides the best soft symbol portion of the composite signal for subsequent demodulation. This bit selection process provides very little head room. Furthermore, it saturates large signal amplitudes. The process is viable because, at large amplitudes, the signal is unlikely to be decoded incorrectly, and thus does not require much resolution at these signal amplitudes. This scheme forces higher resolution in the area around the origin, and saturates large signal amplitudes.
  • flowchart 5000 of the present embodiment shows a specific sequence and quantity of steps
  • the present invention is suitable to alternative embodiments. For example, not all the steps provided for flowchart 5000 are required for the present invention. And additional steps may be added to those presented.
  • flowchart 5000 utilizes a composite test to establish a level of confidence.
  • flowchart 5000 is shown as a single serial process, it can also be implemented as a continuous or parallel process. For example, it is appreciated that flowchart 5000 can be repeated for sequential signal values, either continuously or intermittently.
  • the memory storage for the present embodiment can either be permanent, such as read only memory (ROM), or temporary memory such as random access memory (RAM).
  • Memory 316 can also be any other type of memory storage, capable of containing program instructions, such as a hard drive, a CD ROM, or flash memory.
  • the instructions may be implemented using some form of a state machine.
  • the present invention effectively provides a method and apparatus for improving the capacity, fidelity, and performance of digital communication. More specifically, the present invention provides a method and apparatus for appropriately evaluating received signals for processing into meaningful data, e.g., voice data.
  • the present invention provides a method that overcomes the prior art limitations of selecting a portion of the combined signal for decoding. This consequently improves the quality of the signal and the flexibility of the communication device.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Radio Transmission System (AREA)

Abstract

L'invention concerne un procédé permettant de sélectionner un symbole variable pour une opération ultérieure dans un dispositif de communication. Selon un mode de réalisation, le procédé consiste à recevoir un signal au niveau du dispositif de communication; à démoduler ce signal; à déterminer un niveau de puissance tel que le rapport signal/bruit Eb/Nt; et à choisir un emplacement de bits dudit signal pour une opération ultérieure, en fonction du niveau de puissance déterminé pour ce signal. La puissance du signal et l'emplacement des bits sont mis à jour dans le temps de manière adaptative pour le signal.
EP00989429A 1999-12-22 2000-12-22 Procede et appareil permettant de selectionner un symbole variable de maniere adaptative Withdrawn EP1155511A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US17170099P 1999-12-22 1999-12-22
US171700P 1999-12-22
US677938 2000-10-02
US09/677,938 US6754503B1 (en) 2000-10-02 2000-10-02 Method for adaptively selecting a soft symbol for a subsequent operation a communication device
PCT/US2000/035051 WO2001047137A1 (fr) 1999-12-22 2000-12-22 Procede et appareil permettant de selectionner un symbole variable de maniere adaptative

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JP (1) JP2003518809A (fr)
KR (1) KR100782628B1 (fr)
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KR100782628B1 (ko) 2007-12-06
JP2003518809A (ja) 2003-06-10
WO2001047137A8 (fr) 2001-09-27
WO2001047137A1 (fr) 2001-06-28
CN1320780C (zh) 2007-06-06

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