Concatenated encoding and decoding for multilayer communication protocol
Abstract
An encoding procedure comprising: a coding procedure comprising: encode the systematic bits of a bit stream to define the systematic bits of a bit stream in each of a plurality of memories each intermerse a plurality of buffers (304) with a first code to produce data ias (304) with a first code to produce coded systematic data, the first code being coded, the first code being an external code, in which each of the aforementioned is an external code, in which each of said plurality of buffers includes a buffer buffer includes a system buffer (306) for storing system buffer (306) for storing systematic bits as data not coded before systematic bits as data not coded before the coding of the systematic bits with is of the coding of the systematic bits with said first code and to store a first mentioned portion code and to store a systematic portion of the systematic data encoded systematically of the systematic data encoded; multiplex the content of the plurality of mem; multiplex the content of the plurality of buffers, the aforementioned multiple buffers being performed, said multiplexing being carried out directly on the content of the memory directly on the content of the intermediate memory of each of said intermediate plurality of each of said plurality of buffers (304) and comprises reading buffers (304) and comprises reading a plurality of bits of each buffer of a plurality of bits of each buffer, said plurality of bits coinciding with lia, said plurality of bits coinciding with the length of a radio frame without overloading is the length of a radio frame without overhead such as CRC bits queued for a code as CRC bits queued for an internal code, storing the internal memory content, the contents of the buffer being stored as a result of said intermediate coding as a result of said coding of the systematic bits with said first code of the systematic bits with said first code; and encode the aforementioned igo multiplexed content; and encoding said multiplexed content with a second code to provide a conjunct with a second code to provide a set of radio frames, in which the encoding of the radio frame, in which the coding of said multiplexed content comprises identified multiplexed content comprises identify a bitsa block encode, and then ar a bitsa block encode, and then, encode the block of bits with the second code encode the block of bits with the second code, the second code being said internal code, the second code being said internal code. .

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11 claims: 4 independent, 7 dependent
- 1ES 2 402 472 T3 REIVINDICACIONES 1. Un procedimiento de codificación que comprende:codificar los bits sistemáticos de un flujo de bits en cada una de una pluralidad de memorias intermedias (304) con un primer código para producir datos sistemáticos codificados, siendo el primer código un código externo, en el que cada una de la citada pluralidad de memorias intermedias incluye una memoria intermedia sistemática (306) para almacenar los bits sistemáticos como datos no codificados antes de la codificación de los bits sistemáticos con el citado primer código y para almacenar una porción sistemática de los datos sistemáticos codificados;multiplexar el contenido de la pluralidad de memorias intermedias, realizándose el citado multiplexado directamente sobre el contenido de la memoria intermedia de cada una de la citada pluralidad de memorias intermedias (304) y comprende la lectura de una pluralidad de bits de cada memoria intermedia, coincidiendo la citada pluralidad de bits con la longitud de una trama de radio sin sobrecarga tales como bits de CRC o bits de cola para un código interno, almacenándose el contenido de la memoria intermedia como resultado de la citada codificación de los bits sistemáticos con el citado primer código;y codificar el citado contenido multiplexado con un segundo código para proporcionar un conjunto de tramas de radio, en el que la codificación del citado contenido multiplexado comprende identificar un bloque de bits a codificar, y a continuación, codificar el bloque de bits con el segundo código, siendo el segundo código el citado código interno.
- 2El procedimiento como se reivindica en la reivindicación 1, en el que la citada codificación de bits sistemáticos en cada una de la pluralidad de memorias intermedias (304) con el primer código comprende:codificar los bits sistemáticos en cada una de la pluralidad de memorias intermedias con un código de bloque.
- 3El procedimiento como se reivindica en la reivindicación 2, en el que la citada codificación de los bits sistemáticos en cada una de la pluralidad de memorias intermedias con un código de bloque comprende:codificar los bits sistemáticos en cada una de la pluralidad de memorias intermedias con un código de Reed - Solomon.
- 4El procedimiento como se reivindica en la reivindicación 1, en el que la citada multiplexación del contenido de la pluralidad de memorias intermedias comprende:proporcionar un bloque de bits sucesivamente desde cada una de la pluralidad de memorias intermedias.
- 5El procedimiento reivindicado en la reivindicación 4, en el que proporcionar el bloque de bits sucesivamente de cada una de la pluralidad de memorias intermedias (304) comprende:proporcionar el bloque de bits que comprende una fila de cada una de la pluralidad de memorias intermedias, estando dispuestos los citados bits en filas en cada una de las citadas memorias intermedias.
- 6El procedimiento reivindicado en la reivindicación 1 en el que la citada identificación del bloque de bits a codificar comprende:identificar el bloque de bits recibidos de al menos una de la pluralidad de memorias intermedias.
- 7Un aparato para codificar, que comprende:una pluralidad de memorias intermedias (304);una pluralidad de codificadores externos (310), estando acoplado cada uno de la citada pluralidad de codificadores en comunicación con una de la citada pluralidad de memorias intermedias (304), en el que la citada pluralidad de memorias intermedias está configurada para recibir los bits sistemáticos de un flujo de bits, en el que cada uno de la citada pluralidad de codificadores externos es para codificar los citados bits sistemáticos de una memoria intermedia correspondiente de la citada pluralidad de memorias intermedias para producir datos sistemáticos codificados, en el que cada una de la citada pluralidad de memorias intermedias incluye una memoria intermedia sistemática (306) para almacenar los bits sistemáticos como datos no codificados antes de la codificación de los bits sistemáticos con el citado código externo y para almacenar una porción sistemática de los datos sistemáticos codificados;un multiplexor (312) acoplado en comunicación con la citada pluralidad de memorias intermedias, estando configurado el citado multiplexor para realizar la multiplexación directamente sobre el contenido de la memoria intermedia de cada una de la citada pluralidad de memorias intermedias y comprende la lectura de una pluralidad de bits de cada memoria intermedia, coincidiendo la citada pluralidad de bits con la longitud ES 2 402 472 T3 de una trama de radio sin sobrecarga tales como los bits de CRC o los bits de cola para un código interno, estando almacenado el contenido de la memoria intermedia como resultado de la citada codificación de los bits sistemáticos con el citado código externo;y un codificador interno (314) acoplado en comunicación al citado multiplexor (312), en el que el codificador interno está configurado para identificar un bloque de bits a codificar y codificar el bloque de bits con el citado código interno.
- 8El aparato como se reivindica en la reivindicación 7, en el que cada una de la citada pluralidad de memorias intermedias está configurada para:almacenar los bits sistemáticos y los bits de paridad.
- 9El aparato como se reivindica en la reivindicación 7, en el que cada uno de la citada pluralidad de codificadores (310) está configurado para:codificar los bits sistemáticos para proporcionar los bits de paridad.
- 10El aparato como se reivindica en la reivindicación 9, en el que cada uno de la citada pluralidad de codificadores (310) está configurado para:codificar los bits sistemáticos con un código de bloque.
- 11El aparato como se reivindica en la reivindicación 7, en el que cada uno de la citada pluralidad de codificadores (310) está configurado para:codificar los bits sistemáticos con un código de Reed - Solomon.
Independent claims11
60 paragraphs in 7 sections, as filed
ES 2 402 472 T3
DESCRIPTION
Concatenated encoding and decoding for multi-layer communication protocol
Background
Field
The present invention relates to communication systems. More particularly, the present invention relates to a system and method for reducing the complexity of decoding in a communication system.
Background
Communication systems have been developed to allow the transmission of information signals from a source station to a physically different destination station. When the information signal is transmitted from the originating station on a communication channel, the information signal is first converted into a form suitable for efficient transmission on the communication channel. Conversion, or modulation, of the information signal involves varying a parameter of a carrier wave in accordance with the information signal, such that the spectrum of the resulting modulated carrier is confined within the bandwidth of the communication channel. At the destination station, the original information signal is replicated from the modulated carrier wave received on the communication channel. Such a replication is generally achieved using an inverse of the modulation process employed by the home station.
Modulation also facilitates multiple access, that is, simultaneous transmission and / or reception of several signals over a common communication channel. Multiple access communication systems often include a plurality of subscriber units that require intermittent service of relatively short duration rather than continuous access to the common communication channel. Various multiple access techniques are known in the art, such as time division multiple access (TDMA), frequency division multiple access (FDMA), and amplitude modulation multiple access (AM). Another type of multiple access technique is a code division multiple access (CDMA) spread spectrum system that conforms to the TIA / EIA / IS-95 Mobile Station - Base Station Compatibility Standard for Spread Spectrum Cellular System. Dual Mode Broadband, hereinafter referred to as the IS-95 standard. The use of CDMA techniques in a multiple access communication system is disclosed in US Patent No. 4,901,307 entitled WIDESPREAD MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR LAND REPEATERS, and US Patent No. 5,103,459 entitled SYSTEM AND PROCEDURE FOR GENERATING WAVE FORMS IN A CDMA CELLULAR TELEPHONE SYSTEM, both assigned to the assignee of the present invention.
A multiple access communication system can be wireless or wired and can carry voice and / or data. An example of a communication system that carries both voice and data is a system in accordance with the IS-95 standard, which specifies transmitting voice and data over the communication channel. A procedure for transmitting data in fixed-size code channel frames is described in detail in US Patent No. 5,504,773 entitled PROCEDURE AND APPARATUS FOR THE FORMATTING OF DATA FOR TRANSMISSION, assigned to the assignee of the present invention. According to the IS-95 standard, data or voice is divided into code channel frames that are 20 milliseconds wide with data rates as high as 14.4 Kbps. Additional examples of communication systems that carry both voice and data include communication systems in accordance with the Third Generation Partnership Project (3GPP), carried out in a set of documents that includes Document numbers 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (W-CDMA standard), or Physical Layer Standard for Spread Spectrum Systems cdma2000 TR-45.5 (IS-2000 standard).
An example of a data-only communication system is a high data rate (HDR) communication system that conforms to the industry standard TIA / EIA / IS-856, referred to herein as the IS standard. -856. This HDR system is based on a communication system disclosed in the application in process together with the present one with serial number 08 / 963.386, entitled PROCEDURE AND APPARATUS FOR TRANSMISSION OF DATA PACKETS WITH HIGH SPEED, filed on November 3, 1997, and assigned to the assignee of the present invention. The HDR communication system defines a set of data rates, ranging from 38.4 kbps to 2.4 Mbps, in which an access point (AP) can send data to a subscriber station (access terminal, AT ). Because the AP is analogous to a base station, the terminology with respect to cells and sectors is the same as with respect to voice systems.
In a multiple access communication system, communications between users are carried out through one or more base stations. A first user at a subscriber station communicates with a second user at a second subscriber station by transmitting data to a base station on a reverse link. The base station receives the data and can route the data to another base station. The data is transmitted on a direct link from the same base station, or from the other base station, to the second subscriber station. Forward link refers to the transmission from a base station to a subscriber station and the
ES 2 402 472 T3 reverse link refers to transmission from a subscriber station to a base station. Also, communication can be conducted between a first user at a subscriber station and a second user at a land line station. A base station receives data from the user on a reverse link, and routes the data through a public switched telephone network (PSTN) to the second user. In many communication systems, eg IS-95, W-CDMa, IS-2000, the forward link and the reverse link are assigned separate frequencies.
The wireless communication service described above is an example of a point-to-point communication service. In contrast, broadcast services provide a point-to-multipoint communication service. The basic model of a broadcast system consists of a broadcast network of users served by one or more central stations, which transmit to users information with certain content, for example, news, movies, sporting events and the like. Each user subscriber station in the broadcast network monitors a common forward link broadcast signal. Because content is fixed by the central station, users generally do not communicate back. Commonly used examples of broadcast service communication systems are TV broadcasts, radio broadcasts, and the like. Such communication systems are generally highly specialized, purpose-built communication systems. With recent advancements in wireless cellular telephone systems, there has been an interest in utilizing primarily the existing infrastructure of point-to-point cellular telephone systems for broadcast services (As used herein, the "Cellular systems" encompasses communication systems that use both cellular and PCS frequencies.)
The information signal to be exchanged between terminals in a communication system is often organized in a plurality of packets. For the purposes of this description, a packet is a group of bytes, including data (payload) and control elements, arranged in a specific format. The control elements comprise, for example, a preamble and a quality metric. The quality metric comprises, for example, cyclic redundancy check (CRC), parity bits, and other types of metrics known to those of skill in the art. The packets are then formatted to fit into a frame according to a communication channel structure. The properly modulated frame that travels between the source terminal and the destination terminal is affected by the characteristics of the communication channel, for example, signal-to-noise ratio, fading, time variation, and other features of this type. Such characteristics affect the modulated signal differently on different communication channels. As a consequence, transmitting a modulated signal over a wireless communication channel requires different considerations than transmitting a modulated signal over a wired-type communication channel, for example a coaxial cable or an optical cable. In addition to selecting an appropriate modulation for a particular communication channel, other methods have been devised for the protection of the information signal. Such procedures comprise, for example, encoding, symbol repeating, interleaving, and other procedures that will be known to one of ordinary skill in the art. However, these procedures increase the overhead. Therefore, an engineering compromise must be reached between the reliability of the information signal delivery and the amount of overhead. Even with the information signal protection explained above, the communication channel conditions can degrade to the point where the destination station may not be able to decode (erase) some of the packets. In data-only communication systems that allow communication of a feedback from a destination terminal to the source terminal, a solution is to retransmit the undecoded packets using an Automatic Retransmission Request (ARQ) made by the destination station. to the station of origin. However, under certain conditions, the ARQ can overload the communication system. Furthermore, as explained with regard to broadcast communication systems, subscribers do not communicate back to the base station. As a consequence, other means of information protection are desirable.
A patent application in process together with the present one, serial number 09 / 933,912, entitled PROCEDURE AND SYSTEM FOR THE USE OF AN EXTERNAL DECODER IN A COMMUNICATION SYSTEM OF EMISSION SERVICES, filed on August 20, 2001 and assigned to the assignee of The present invention explains in detail the use of an external decoder in a broadcast system. As described in co-pending patent application serial number 09 / 933,912, the information bit stream to be transmitted is first encoded by an external decoder and the encoded stream is then encoded by a internal encoder. As illustrated in FIG. 1, the information bit stream to be transmitted 102, originating from the upper layers, is provided to a transmission buffer 104. The transmit buffer is illustrated in more detail in FIG. 2. Referring to FIG. 2, the bits fill the systematic portion 204 (1) of the transmit buffer 104 (of FIG. 1) row by row, left to right. The systematic portion 204 (1) comprises k rows 208 of length L. Referring back to FIG. 1, once the systematic portion 204 (4) (of FIG. 2) is full, the outer block encoder 106 is activated to perform column-direction encoding, accordingly. the bits in the systematic portion 204 (1) (of FIG. 2) to generate (n-k) additional rows 210 (of FIG. 2) of parity bits. This column-wise operation is performed column by column for the external binary code, that is, m = 1. For non-binary codes, that is, m> 1, every m adjacent columns in a row are treated as a bit-m symbol. The bit-m symbols along the upper k rows are read by the external encoder to produce n-k bit-m symbols that fill the corresponding lower rows n-k of these columns.
ES 2 402 472 T3
The external encoder comprises, for example, a systematic Reed-Solomon (SR) encoder. Referring back to Figure 1, the contents of the transmission buffer 104 are then provided to a physical layer 108. In the physical layer 108, the individual frames are encoded by an internal encoder (not shown), which results in scrambled frames. The structure of the internal decoder is well known to those of skill in the art. The systematic rows and parity rows in the buffer can be interleaved during transmission to reduce the possibility of a large number of systematic rows erased when the total number of erasures of internal code exceeds the correction capacity of the outer code. The frames are further processed in accordance with a selected modulation scheme, eg, cdma2000, WCDMA, UMTS, and other modulation schemes known to those of skill in the art. The processed frames are then transmitted on a communication channel 110.
The transmitted frames are received at the destination station and provided to a physical layer 112. At physical layer 112, individual frames are demodulated and provided to an internal decoder (not shown). The internal decoder decodes each frame, and if the decoding is successful, it outputs a correctly decoded frame; or if decoding is unsuccessful, declare a delete operation. Decoding success or failure must be determined with high precision, achieved for example by including a long (for example 16 bit) cyclic redundancy check (CRC) in the frame after external encoding and before of the internal encoding. The included CRC obtained from the decoded frame is compared with a CRC calculated from the bits of the decoded frame, and if the two CRCs are identical, the decoding is declared successful.
If the internal decoder cannot decode the frame, the decoder declares an erasure, and provides an external block decoder 116 with an indication that the frame is missing. The process continues until there are as many parity frames correctly received and passed to a parity portion 114 (2) of a receive buffer 114, as there are systematic erased frames. The receiver stops receiving any remaining frames and the external decoder (not shown) is activated to recover the erased systematic frames. The recovered systematic frames are passed to the upper layer.
It is well known in the art that the decoding / error correction calculation complexity increases with increasing values of the number of rows in the transmit buffer 104. Because the decoding / error calculation complexity affects the hardware complexity at the receiving terminal, as well as power consumption, there is a need in the art for a method and system.
Attention is drawn to the following document: Lou, Podilchuk, Chio: Progressive Real-Time Video Broadcasting Over 2G and 3G Wireless Systems, Proceedings of the 11th IEEE International Symposium on Internal and Mobile Personal Radio Communications, PIMRC 2000, Vol. 2, September 18-21, 2000, pages 1550-1554 (XP010520891). The article explains a progressive video codec with video scalability. The article proposes an unequal protection scheme in the application layer for the video bitstream that works in concatenation with the channel codes in the physical layer of current cellular systems.
Attention is also drawn to the following document: Greg SHERWOOD et al., Error Protection for Progressive Image Transmission on Non-Memory and Fading Channels, IEEE Transactions on Communications, vol. 46, number 12, December 1, 1998, XP011009310, ISSN: 0090 to 6778. This document discloses a coding procedure for wireless applications based on a product code of an external Reed-Solomon code and an internal RCPC code.
Attention is also drawn to US 6 047 395, which describes an error correction processor for correcting errors in binary data read from disk storage medium, in which the binary data comprises first and second sets of words. of intersecting ECC code, of a multidimensional code word. The error correction processor comprises a data buffer for storing the ECC code words read from the disk storage medium, a syndromes generator for generating ECC syndromes in response to a code word in the second set; a polynomial error locator generator to generate an error locating polynomial sigma (x) in response to ECC syndromes, a selector to select between the error locator polynomial sigma (x) and an erasure polynomial sigma (x) EP , in which: (i) the sigma (x) polynomial erasure EP is generated while the first set of codewords is being processed, and (ii) the sigma (x) polynomial erasure EP is used to correct at least two codewords in the second set, and an error corrector to generate correction values in response to either the sigma (x) polynomial error locator or the sigma (x) erasure polynomial EP produced as output by the selector, correction values to correct for errors in the code words in the second set.
Summary
According to the present invention there is provided a coding method, as set out in claim 1, an apparatus for encoding, as set out in claim 7. Embodiments of the inventions are claimed in the dependent claims.
ES 2 402 472 T3
Detailed description
Definitions
The word "exemplary" is used herein to mean that it serves as an example, case, or illustration. Any embodiment described herein as exemplary should not necessarily be construed as preferred or advantageous over other embodiments.
The term "point-to-point communication" is used herein to mean a communication between two subscriber stations on a dedicated communication channel.
The terms broadcast communication or point-to-multipoint communication are used herein to mean a communication in which a plurality of subscriber stations are receiving communication from one source.
The term packet is used herein to mean a group of bits, including data (payload) and control elements, arranged in a specific format. Control elements comprise, for example, a preamble, a quality metric, and others that are known to those of skill in the art. The quality metric comprises, for example, a cyclic redundancy check (CRC), a parity bit, and others that are known to those of skill in the art.
The term "access network" is used herein to mean a collection of base stations (BS) and one or more base station controllers. The access network carries data packets between multiple subscriber stations. The access network can further be connected to additional networks outside the access network, such as a corporate intranet or the Internet, and can carry data packets between each access terminal and such external networks.
The term "base station" is used herein to mean the hardware with which the subscriber stations communicate. Cell refers to hardware or a geographic coverage area, depending on the context in which the term is used. A sector is a partition of a cell. Because a sector has the attributes of a cell, the teachings described in terms of cells are easily extended to sectors.
The term "subscriber station" is used herein to mean the hardware with which an access network communicates. A subscriber station can be mobile or stationary. A subscriber station can be any data device that communicates over a wireless channel or through a wired channel, for example using fiber optic or coaxial cables. A subscriber station can further be any of a number of device types, including, but not limited to, a PC card, an internal or external compact flash modem, or a cordless or wired telephone. A subscriber station that is in the process of establishing an active traffic channel connection with a base station is said to be in a connection setup state. A subscriber station that has established an active traffic channel connection with a base station is called an active subscriber station, and is said to be in a traffic state.
The term "physical channel" is used herein to mean a communication path over which a signal is propagated, described in terms of modulation and coding characteristics.
The term "logical channel" is used herein to mean a communication path within the protocol layers of either the base station or the subscriber station.
The term "communication channel / link" is used herein to mean a physical channel or a logical channel according to context.
The term "reverse communication link" is used herein to mean a communication channel / link through which the subscriber station sends signals to the base station.
A forward link / channel is used herein to mean a communication channel / link through which a base station sends signals to a subscriber station.
The term "soft handoff" is used herein to mean a communication between a subscriber station and two or more sectors, in which each sector belongs to a different cell. Reverse link communication is received by both sectors and forward link communication is carried simultaneously on the forward links of the two or more sectors.
The term "smoother handoff" is used herein to mean a communication between a subscriber station and two or more sectors, in which each sector belongs to the same cell. Reverse link communication is received by both sectors and forward link communication is performed simultaneously on one of the forward links of the two or more sectors.
ES 2 402 472 T3
The term erasure is used herein to mean a failure to recognize a message.
The term "dedicated channel" is used herein to mean a channel modulated by information specific to an individual subscriber station.
The term "common channel" is used herein to mean an information modulated channel shared between all subscriber stations.
The term physical layer is used exclusively in the present specification to mean that part of the communication protocol between a source terminal and a destination terminal that is responsible for the transmission and reception of data. The physical layer corresponds to Layer 1 in the model of the International Standards Organization for the Interconnection of Open Systems.
The term "upper layer or upper layers" is used exclusively in the present specification to mean that part of the communication protocol between a source terminal and a destination terminal is above a physical layer. The highest layers correspond to layers 2 to 7 in the International Standards Organization model for Open Systems Interconnection.
Description
In accordance with one embodiment of the present invention, as illustrated in FIG. 3, the information bit stream to be transmitted 302, originating from the upper layers, is demultiplexed and provided to transmission buffers 304 (i). The bits fill the systematic portion 306 (1) of the transmit buffer 304 (1) row by row, from left to right. The systematic portion 306 (1) comprises k rows of length L. In one embodiment, the length L of the buffer matches the length of a radio frame without overhead (for example, the CRC to assist the internal decoder and the bits queue for the internal encoder). Once the systematic portion 306 (1) of the transmit buffer 304 (1) is full, the procedure is repeated for the remaining transmit buffers 304 (2) - 304 (p). Once the systematic portions 306 (i) of the transmit buffers 304 (i) are full, the external block encoders 310 (i) are activated to perform column-wise encoding of the bits in the systematic portion 306 (i) to generate (n-k) additional rows of parity bits 308 (i). This column-wise operation is performed column by column for the external binary code, that is, m = 1. For non-binary code, that is, m> 1, every m adjacent columns in a row is treated as a bit-m symbol. The bit-m symbols along the upper k rows are read by the external encoder to produce n-k bit-m symbols that fill the corresponding lower n-k rows of these columns.
In another embodiment, the length L of the buffer is equal to the number of bits in the radio frame, without the overhead, divided by m, the dimension of the external encoder code. In this embodiment, the first m rows of transmission buffers 304 (i) are sent in the first radio frame, the second m rows of bits are sent in the second radio frame, until the full buffer has been transmitted. Once the systematic portion 306 (1) of the transmission buffer 304 (1) is full, the procedure is repeated for the remaining transmission buffers 304 (2) - 304 (p). Once the systematic portions 306 (i) of the transmission buffers 304 (i) are full, the external block encoders 310 (i) are activated to execute encoding in the column direction of the bits in the portion systematic 304 (i) to generate m (n-k) additional rows of parity bits 308 (i). This column-wise operation is performed column by column for the external binary code, that is, m = 1. For non-binary code, that is, m> 1, every m rows in a column form a bit symbol - m. The k symbols in the upper k rows in the column are read by the external encoder to produce (n - k) m-bits that fill the corresponding lower rows m (n - k) of this column.
In one embodiment, the external encoders 310 (i) comprise a Reed-Solomon (RS) systematic encoder. The content of the transmission buffers 304 (i) is then provided to a multiplexer 312. Multiplexer 312 cycles through transmit buffers 304 (1) - 304 (p), selecting a successive transmit buffer 304 (i) after a block of bits containing a predetermined number of bits has been sent from a previous buffer 304 (i-1). In one embodiment, the predetermined number of bits in a block equals L. This strategy is intended to evenly distribute data corruption due to disturbance of a physical channel 316 among buffers 304 (i). However, those of ordinary skill in the art will understand that other multiplexing strategies are equally applicable, and may be used without departing from the scope of the invention as defined in the appended claims. The multiplexed bit blocks are provided to a physical layer 314 of the source terminal. At physical layer 314, additional bits of overhead (for example, a CRC check) are added to each of the bit blocks, and the resulting structure is encoded by an internal encoder (not shown), resulting in encoded frames. . The structure of the external and internal encoders and of the multiplexer can be, for example, the structure of figure 3. The frames are further processed according to a selected modulation scheme. In one embodiment, the process is carried out in accordance with the IS-2000 standard. The processed frames are transmitted on a communication channel 3116.
ES 2 402 472 T3
The transmitted frames are received at the destination station (not shown), and provided to a physical layer 318 at the destination station. At physical layer 318, the individual frames are demodulated and provided to an internal decoder (not shown). In one embodiment, the internal decoder decodes each frame, and if the decoding is successful, a correctly decoded frame is generated, or if the decoding is unsuccessful, an erasure is declared. The success or failure of decoding must be determined with great precision. In one embodiment, accuracy is achieved by including a long (eg, 16-bit) cyclic redundancy check (CRC) in the frame after outer encoding and before inner encoding as explained further. up. However, a person of ordinary skill in the art will recognize that other mechanisms for the indication of frame quality may be used. The included CRC obtained from the decoded frame is compared to a CRC calculated from the bits of the decoded frame, and if the two CRCs are identical, the decoding is declared successful. Post-processing in the physical layer continues according to the result of the internal decoder's decision.
The correctly decoded frames are provided to a demultiplexer 320 which distributes the correctly decoded frames among the receive buffer 322 (i), using a procedure inverse to the procedure used for multiplexing. If all the systematic frames k are correctly decoded by the internal decoder for a particular receive buffer, 322 (i), the systematic frames from the systematic portion 324 (i) of the receive buffer 322 (i) are provided to the upper layers.
If the internal decoder cannot decode the frame, the decoder declares an erasure, and provides demultiplexer 324 with an indication that the frame is missing. The demultiplexer 324 provides the information to the external block decoder 328 (i) coupled in communication to the received buffer 322 (i) to which the frame belonged. The process continues until there are enough systematic frames and correctly accumulated received parity frames in the systematic portion 324 (i) and in the parity portion 326 (i) of the receive buffer 322 (i), or until the memory intermediate reception 322 (i) is full. The external decoder (not shown) is then activated to recover the erased systematic frames. The recovered systematic frames are provided to the upper layers.
If the total number of correctly received frames in the reception buffer 322 (i) is less than k, according to one embodiment, the external decoder is not activated as there is no guarantee that the decoding will be successful. The systematic frames received correctly together with the identification of the missing bits are provided to the upper layers. In another embodiment, the receiver uses the decoded bits from the internal decoder (which are unreliable, as indicated by failed CRC checks) to recover bits for the systematic bits. According to one embodiment, the receiver decodes the unreliable bits from the internal decoder and finds the most probable codeword. In the other embodiment, the receiver uses the signal quality measurement of the erased frames in the buffer to choose enough erroneously received frames with the highest signal-to-noise ratio to form a sub-buffer with k rows. The receiver then performs a bit flip (changing a bit value from 0 to a bit value 1 and vice versa one column at a time) and checks if the bit flip has produced a code word. In one embodiment, bit flipping is performed first with the least reliable bits and continues with the bits in the order of increasing reliability of the bits. The reliability of a bit can be determined according to internal decoding metrics, for example, a signal-to-noise ratio and interference during the frame, such as the Yamamoto metric, the recoded symbol error rate, the recoded energy metric, and other metrics that are known to those of ordinary skill in the art, or combinations of the metrics. If no code word was found, bit flipping continues through all remaining columns for all unreliable rows. If no code word was found, bit flipping continues with an increasing number of flipped bits (that is, changing 2 bits at a time, then 3 bits, up to the maximum number of bits), until either a codeword is found or all combinations have been exhausted. In another embodiment, the CRC of the unreliable rows is used to check the overall success of the decoding in this situation. The frames are provided to the upper layers only if the CRC of all the rows correspond, otherwise only the bits of the reliable rows are provided to the upper layers.
To improve decoding reliability, in another embodiment, demodulation and internal decoding are carried out on more than k frames correctly received in a buffer. According to yet another embodiment, internal demodulation and decoding are carried out on all frames in the buffer. In both embodiments, the external decoding is performed on rows k (or km) with the highest quality. The quality can be determined according to internal decoding metrics, for example, a signal-to-noise and interference ratio in the frame, such as the Yamamoto metric, the recoded symbol error rate, the recoded energy metric, and others. parameters that are known to those of ordinary skill in the art, or combinations of the metrics. The use of quality metrics for quality estimation, is described in detail in US Patent No. 5,751,725 entitled PROCEDURE AND APPARATUS FOR DETERMINING THE SPEED OF DATA RECEIVED IN A VARIABLE SPEED COMMUNICATION SYSTEM and in US Patent No. 5,774,496 entitled PROCEDURE AND APPARATUS FOR DETERMINE THE DATA SPEED OF THE DATA TRANSMITTED WITH VARIABLE SPEED IN A COMMUNICATION RECEIVER and both are assigned to the assignee of the present invention.
ES 2 402 472 T3
One of ordinary skill in the art will appreciate that the number of transmit buffers 304, and consequently, receive buffers 322 is a trade-off between processing overhead and the potential amount of data loss. A small value of k, which produces more transmit / receive buffers produces a higher processing overhead. On the other hand, a large value of k resulting in fewer transmit / receive buffers causes the transmit buffer size to increase, leading to discarding a large block of data if the contents of the transmit buffer cannot be recovered due to more row deletions than (n - k). A large transmit buffer size also increases the memory requirement on the destination terminal.
Those skilled in the art will understand that information and signals can be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
Those skilled in the art will further appreciate that the various logic blocks, modules, circuits, and algorithm steps described in connection with the embodiments described herein can be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various components, blocks, modules, circuits, and stages have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software will depend on the particular application and the design limitations imposed on the overall system. Those skilled in the art can implement the described functionality in various ways for each particular application, but such implementation decisions should not be construed as causing a departure from the scope of the present invention.
The various logic blocks, modules, and circuits described in connection with the embodiments described in this document can be implemented or realized with a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable programmed gate (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a procedure or algorithm described in connection with the embodiments described in this document can be performed directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integrated into the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In the alternative, the processor and the storage medium can reside as discrete components in a user terminal.
The foregoing description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but should be granted the broadest scope consistent with the principles and novel features described herein.
A portion of the description in this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction of any of the patent documents or patent description, as it appears in the patent file or records of the Patent and Trademark Office, but is otherwise reserves all copyrights whatever they may be.
Contents7
3 sheets
Sheet 1 Sheet 2 Sheet 3
33 members in 12 offices
Priority claims5
| Document | Office | Kind | Date |
|---|---|---|---|
| 976591 | United States of America | – | |
| 97659101 | United States of America | A | |
| 97659101 | United States of America | A | |
| 976591 | – | – | – |
| US20010976591 | – | – | – |
Members33
| Document | Office | Kind | |
|---|---|---|---|
| US2003072384A1 | United States of America | A1 | |
| WO03034598A2 | World Intellectual Property Organization (WIPO) | A2 | |
| AU2002342013A1 | Australia | A1 | |
| WO03034598A3 | World Intellectual Property Organization (WIPO) | A3 | |
| TW569544B | Taiwan Province of China | B | |
| KR20040041687A | Republic of Korea | A | |
| EP1435134A2 | European Patent Office (EPO) | A2 | |
| CN1602588A | China | A | |
| JP2005532701A | Japan | A | |
| BR0213215A | Brazil | A | |
| KR100892891B1 | Republic of Korea | B1 | |
| JP4274942B2 | Japan | B2 | |
| US7649829B2 | United States of America | B2 | |
| US2010107041A1 | United States of America | A1 | |
| EP1435134B1 | European Patent Office (EPO) | B1 | |
| AT470994T | Austria | T | |
| ATE470994T1 | Austria | T1 | |
| DE60236677D1 | Germany | D1 | |
| CN101848064A | China | A | |
| EP2239856A2 | European Patent Office (EPO) | A2 | |
| CN101867448A | China | A | |
| EP2242181A2 | European Patent Office (EPO) | A2 | |
| US2010272124A1 | United States of America | A1 | |
| EP2242181A3 | European Patent Office (EPO) | A3 | |
| EP2239856A3 | European Patent Office (EPO) | A3 | |
| CN1602588B | China | B | |
| CN101867448B | China | B | |
| EP2242181B1 | European Patent Office (EPO) | B1 | |
| EP2239856B1 | European Patent Office (EPO) | B1 | |
| ES2402472T3This record | Spain | T3 | |
| CN101848064B | China | B | |
| US8713400B2 | United States of America | B2 | |
| US8730999B2 | United States of America | B2 |
Numbers
- Publication
- 2402472
- Publication, DOCDB
- 2402472
- Publication, EPODOC
- ES2402472T
- Application
- 10004607
- Application, DOCDB
- 10004607
- Application, EPODOC
- ES20100004607T
Titles2
- Spanish
- Codificación y decodificación concatenadas para protocolo de comunicación de capas múltiples
- English
- Concatenated encoding and decoding for multilayer communication protocol
Classification
- CPC, 8
- H04L1/0057
- H04L27/26
- H03M13/2909
- H03M13/293
- H03M13/2936
- H04L1/0041
- H04L1/0045
- H04L1/0066
- IPC, 4
- H03M13 29
- H04L1 00
- H03M13 15
- H04J3 00