MXPA01002141A - Codec mode decoding using a priori knowledge - Google Patents

Abstract

A communication system supports multiple source coding/channel coding schemes. A mode indicator can be transmitted with payload data to inform the receiver of the particular scheme currently being employed. The mode indicator may be encoded using a relatively weak channel coding to minimize extraneous overhead transmissions. To enhance the likelihood of successfully decoding the mode indicator, which has information that is highly important in successfully decoding the payload data, various value likelihood parameters can be calculated and combined to identify a most likely mode. Included in the likelihood (soft) parameters is one parameter which can be calculated based on a model of the mode information's likely value (e.g. Markov model).

Description

COPEC MODE DECODING USING PREVIOUS KNOWLEDGE BACKGROUND The present invention is generally related to modeling in the field of communication systems and, more particularly, to the determinant coding modes in digital communication systems that support the schemes of communication. error correction coding without ground channel / multiple telephone signals. The growth of commercial communication systems and, in particular, the explosive growth of cellular radiotelephone systems, have imposed system designers to look for ways to increase system capacity without reducing the quality of communication beyond the tolerance thresholds. of the consumer. One technique to achieve these objectives involved switching systems, where analog modulation was used to print data on a carrier wave, to systems where digital modulation was used to print the data on carrier waves. In digital wireless communication systems, standardized air interfaces specify most of the parameters of the system, including the types that encode the telephone signal, the display format, the communication protocol, etc. For example, the European Telecommunications Standards Institute (ETSI) has specified a Global System for Mobile Communications (GSM) standard that uses time division multiple access (TDMA) to communicate with control, voice and data information about physical radio frequency (RF) channels or links using a modulation scheme of Minimum Displacement Modification with Gaussian Filter (GMSK) at a symbol rate of 271 ksps. In the Association of the Telecommunications Industry of the United States of America (TIA) has published a number of Internal Standards, such as IS-54 and IS-136, which define various versions of advanced digital mobile telephony service (D-AMPS) ), a TDMA system that uses a differential quadrature phase shift modulation (DQPSK) scheme for communication data over RF links. TDMA systems subdivide the available frequency into one or more RF channels. The RF channels are also divided into a number of physical channels that correspond to broadcast boxes in TDMA boxes. The logical channels are formed in one or several physical channels where modulation and coding is specified. In these systems, mobile stations communicate with a plurality of dispersed base stations by transmitting and receiving bursts of digital information over uplink and downlink RF channels. The growth number of mobile stations in use today has generated the need for more voice and data channels within cellular telecommunication systems. As a result, the base stations have separated more closely, with an increase in interference between mobile stations operating on the same frequency in neighboring or closely spaced cells. In fact, some systems now use code division multiple access (CDMA), using a form of spread spectrum modulation where the signals intentionally share the same time and frequency. Although digital techniques provide a greater number of useful channels of a given frequency spectrum, there still remains a need to maintain the interference at acceptable levels, or more specifically to monitor and control the carrier-to-interference-to-interference-resistance ratio. say, carrier to interference ratio (C / I)). Another factor which is widely important in providing various communication services is the desired / required user's bit rate for data that is • transmit over a particular connection. For example, for voice and / or data services, the user's bit rate corresponds to voice quality and / or data production, with a much higher user bit rate that produces much better quality of and / or higher data production. The total user bit rate is determined by a selected combination of techniques for telephone signal coding, channel coding, modulation, and resource allocation, for example, for a TDMA system, the latter technique may refer to the frame number of the device. assignable emission per connection, for CDMA system, this last parameter can refer to the number of assignable codes per connection. Telephone signal coding techniques (or more generally "source coding") are used to compress the input information into a format that uses an acceptable amount of bandwidth, but from which an intelligible output signal can be produced. There are many different types of telephone signal coding algorithms, for example, residual excited linear prediction (RELP), regular pulse excitation (RPE), etc., the details of which are not particularly relevant to this invention. More significant in this context is the fact that several telephone signal coders have several output bit rates and that, as one would expect, telephone signal coders have a higher output bit rate that tends to provide consumer acceptance. Larger its reproduced voice quality than those that have a lower output bitrate. As an example, consider that the more traditional wire-based telephone systems use the coding of PCM telephone signals at 64 kbps, while the GCM systems employ an RPE telephone signal coding scheme that operates at 13 kbps. In addition to telephone signal coding, digital communication systems also employ various techniques to handle information received in an erroneous manner. Generally speaking, these techniques include those that help a receiver correct erroneously received information, for example , error correction techniques without return channel (FEC), and those that allow erroneously received information to be transmitted back to the receiver, for example automatic re-transmission request (ARQ) techniques. FEC techniques include, for example, convolutional or block coding (collectively referred to herein as "channel coding") of the data prior to modulation. Channel coding involves representing a certain number of data bits that use a certain number of code bits. Thus, for example, it is common to refer to convolutional codes for their code rates, for example, 1/2 and 1/3, where the lower code rates provide greater error protection but bit rates of the lowest user for a given channel bit rate. Conventionally, each of the techniques that impact the user's bit rate were set for any given radio communication system, or at least for the duration of a connection established by a radio communication system. That is, each system established connections that operated with a type of telephone signal coding, a type of channel coding, a modulation type and a resource assignment. More recently, however, the dynamic adaptation of these techniques has become a popular method to optimize the performance of the system against the numerous parameters that can vary rapidly over time, for example, the propagation characteristics of the radio of the radio communication channels, the system load, the user's bit rate requirements, etc. For example, different modulations have been dynamically assigned to selectively take advantage of the resistances of the individual modulation schemes and to provide larger user bit rates and / or increase the noise and interference resistance. An example of a communication system employing multiple modulation schemes is found in US Patent No. 5, 577,087. A technique for switching between 16QAM and QPSK is described herein. The decision to switch between the types of modulation is made based on the quality measures, however this system uses a constant user bit rate which means that a change in the modulation scheme also requires a change in the speed of channel bits, for example, the number of broadcast frames used to support a transmission channel. It is seen that many different combinations of these processing techniques can be used selectively as between different connections supported by a radio communication system and during the lifetime of an individual connection. However, the receiver must be aware of the types of processing that are used by the transmitter in order to properly decode the information with the reception. Generally, there are two categories of techniques for informing the receiver about the processing techniques associated with a radio signal: (1) explicit information, ie, a message field within the transmitted information that has a value so that it is indicative of the types of processing and (2) implicit information, which is sometimes referred to as "blind" decoding, where the receiver determines the processing performed by the transmitter by analyzing the received signal. This last technique is used in CDMA systems that operate in accordance with the TIA / EIA IS-95 standard. Explicit information is sometimes considered to be preferable since it reduces the processing delay in the receiver, although it comes at the cost of the transmitter's need to include additional operational bits together with the user's data. Of particular interest to the present invention are the indicators so as to reflect the combination of the telephone signal coding, channel coding currently employed by the transmitter. For example, when channel conditions are good, the transmitter may employ a telephone signal coding / channel coding mode that provides a bit rate encoding the high source and a relatively low degree of error protection. Alternatively, when the channel conditions are poor, then a coding mode can be employed which provides a low bit rate telephone signal encoding technique coupled with a relatively high degree of error protection. Systems can quickly switch between these different encoding modes based on changes of variation in channel conditions. As mentioned above, a mode indicator can be transmitted to the receiver (either the base or the mobile station of the receiver) so that it can employ the appropriate telephone signal decoding / decoding techniques. Normally, this mode indicator can include only some, for example, two bits that are transported along with the data fields. Thus, it will be appreciated that it is particularly important for the receiver to be able to exactly decode the encoding mode indicator since, otherwise, an entire frame of data may be unrecoverable. This desire for the exact reception of the indicate mode can lead designers to strongly protect the mode indicator with heavy channel coding. However, the use of heavy channel coding implies higher redundancy, which means that more bits are transmitted for the mode indicator field. This is, as explained in the above, undesirable, since the operating bits should be decreased, but not increased. In this way, it may be desirable to provide technique and systems to increase the likelihood that mode indicators, such as the encoding mode indicator, will be properly decoded, while at the same time decreasing the number of operational bits that will be transmitted with the payload data.

COMPENDIUM OF THE INVENTION These and other disadvantages and limitations of conventional methods and systems for communicating information are overcome in accordance with the present invention, wherein the relatively weak channel coding (eg, convolutional coding and / or block coding) are used. to protect the information transmitted on the air interface. In this way, the transmission of operational bits is decreased, thereby maximizing the production of user data for a given resource allocation. The mode information may comprise, for example, an indicator so as to inform a receiver of the combination of telephone signal coding / channel coding currently used to encode the payload data, a request so as to inform a transmitter in a particular code mode desired by a receiver for the subsequently transmitted information blocks or frames and / or channel measurement information, which acts as an implicit request for a particular code mode that is provided by the transmitter. In order to compensate for the relatively weak channel coding used to protect the mode information, exemplary embodiments of the present invention increase the exact decoding of the mode information by providing a plurality of estimated or estimated probable parameters that combine to maximize a probability. of the correct determination of the value of the mode information. For example, a first probability parameter may be derived from the flexible information that is available as part of the decoding of the mode information field, for example, in a Viterbi decoding process. A second probability parameter can be derived from a model created specifically to use prior knowledge of the information itself. These two probability parameters can be combined to identify the information in current mode (most likely).

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects, features and advantages of the present invention will become more apparent upon reading the following detailed description, taken in conjunction with the accompanying drawings, wherein: Figure 1 is a block diagram of a exemplary GSM communication system advantageously using the present invention; Figure 2 (a) represents a codec mode used in a conventional GSM system; Fig. 2 (b) represents a conventional bitmap in a telephone signal frame for the unequal error protection coding; Figure 3 (a) is a block diagram illustrating the multiple, individual codec modes that can be selected to process data to be transmitted and a correspondingly indicator according to an exemplary embodiment of the present invention; Figure 3 (b) is another block diagram illustrating another exemplary technique for generating multiple codee modes; and Figure 4 depicts a block diagram of a receiver that includes a processor in a likely manner and a mode information model in accordance with an exemplary embodiment of the present invention. DETAILED DESCRIPTION The following exemplary embodiments are provided in the context of TDMA radio communication systems. However, those skilled in the art will appreciate that this access methodology is merely used for purposes of illustration and that the present invention can be easily applied to all types of access methodology including frequency division multiple access (FDMA), TDMA, multiple access by code division (CDMA) and hybrids thereof. On the other hand, the operation according to the GSM communication systems is described in the documents of the European Institute of Communication Standards (ETSI) ETS 300 573, ETS 300 574 and ETS 300 578, which are incorporated herein by reference. Thus, the operation of the GSM system is only described herein to the extent necessary to understand the present invention. However, the present invention is described in terms of exemplary embodiments in a GSM system, those skilled in the art will appreciate that the present invention can be used in a wide variety of other digital communication systems, such as those based on PDC or D standards. -AMPS and increases thereof. Referring to Fig. 1, a common system is represented: according to an exemplary embodiment of the present invention. The system 10 is designed as a 'hierarchical network with multiple levels for handling calls. Using a set of uplink and downlink frequencies, mobile stations 12 operating within the system 10 participate in calls using broadcast frames assigned to them on these frequencies. At a higher hierarchical level, a group of Mobile Switching Centers 14 (MSCs) are responsible for routing calls from a source to a destination. In particular, these entities are responsible for the establishment, control and termination of calls. One: of the MSCs 14, known as the head MSC, handles' communication with a Public Switched Telephone Network 18 (PSTN), or other public and private networks.

At a lower hierarchical level, each of the MSCs 14 is connected to a group of base station controllers 16 (BSCs). Under the GSM standard, the BSC 16 communicates with an MSC 14 under a standard interface known as the A interface, which is based on the Mobile Application Part of the CCITT Signaling System No. 7. At a still lower level of hierarchy, each of the BSCs 16 controls a group of base transmitting receiver stations 20 (BTSs). Each BTS 20 includes a number of TRXs (not shown), which use the uplink and downlink RF channels to serve a particular common geographic area, such as one or more communication cells 21. The BTSs 20 mainly provide the links RF for transmitting and receiving bursts of data to and from mobile stations 12 within its designated cell.In an exemplary embodiment, a number of BTSs 20 is incorporated into a radio base station 22 (RBS). to be, for example, configured according to an RBS-2000 product family, whose products are offered by Telefonaktiebolaget LM Ericsson, the assignee of the present invention For more details regarding the exemplary mobile station 12 and the RBS implementations 22, the interested reader refers to the US Patent Application Serial No. 08 / 921,319, entitled "A Link Adaptation Method for Links using Modulation Schems That Have Differente Symbol Rates ", for Magnus Frodigh et al., And presented on August 29, 1997, description of which is expressly incorporated herein by reference. In accordance with exemplary embodiments of the present invention, information transmitted between a BTS 20 and a mobile station 12 can therefore be processed using different codee modes. The phrase "code mode" as used herein refers to a combination of source coding (eg, telephone call coding) and channel coding, although the present invention can also be applied to the transmission and reception of other types. of mode indicators and, even more generally, to the transmission and reception of other information on an air interface. To more fully understand the exemplary modes for the indicators, requests and information associated with it may be protected, transmitted and encoded, which is considered the exemplary GSM codeine mode illustrated in Figures 2 (a) and 2 (b). Figure 2 (a) represents a portion of the signal processing path transmitted downstream of the A / D converter (not shown) that digitizes an exemplary input audio signal. A block of 160 samples is presented in an RPE telephone call encoder 30 that operates in accordance with well-known GSM specifications (eg GSM 06.53) to produce two categories of output bits, class 1 182 bits and class 2 bits 78, for a total output bit rate of 13 kbps. As seen in Figure 2 (b), class 1 bits are further divided into class class bits and class Ib bits, both of which are input to a channel encoder 32, which performs convolutional 1/2 speed decoding. . This results in a production of 378 bits from the channel encoder 32, including parity bits 3 associated with class bits la and four end bits associated with class Ib bits. This composite process can be considered to be an example of an individual code mode. However, future systems that provide a plurality of different codee modes are displayed. For example, as conceptually illustrated in Figure 3 (a), there may be two different telephone call coders and two different channel coders that can be used in various combinations to encode bits before transmission. A first telephone call code 40 can operate to process the digital samples and provide an output bit rate of X kbps, while a second telephone call encoder 42 can process the digital input samples to provide an output bit rate of And kbps, where X >; Y. Similarly, the different channel coders 44 and 46 (in this example, convolutional coders, although one or both may alternatively be block coders) provide different degrees of error protection by virtue of their different speeds 1 / A and 1 / B, respectively, wherein A > B. In this way, it can be seen that by using the mode control processor 48 together with multiplexers 50 and 52 to select a path, for example, a combination of telephone call encoder and channel encoder for this example, to process a particular block or payload data frame, four different codee modes are available. Many other techniques are, of course, available to create multiple codec modes in a transmitter. Consider the example in Figure 3 (b), where a plurality of source coders (eg, telephone call) 60, 62, 64 and 66 are provided in selectable transmit signal processing paths. Each encoder has a different output speed (X> Y> Z> A kbps) and is associated with a different one of the channel encoders 68, 70, 72 and 74. To provide a uniform output data rate of F kbps between different selectable paths (which may be desirable for similar resource allocation or connection), the channel encoders may be designed so that the amount of redundancy added to the data stream encoded by the source is greater for the encoder than bit rate source and smaller for higher bit rate source encoders. As in the previous example, the particular codec mode selected for any given frame or data frame can be controlled for example, by a mode control processor 76 and multiplexer 78. Regardless of the technique used on the transmission side to provide the Different codec modes, in order to be able to correctly decode the received data, a receiver will need to know the codec mode used by the transmitter to process any given frame or frame of received data. In accordance with exemplary embodiments of the present invention, this can be achieved by transmitting a mode indicator from the transmitter to the receiver together with or in progress of the data block or frame to which it relates. In the example of Figures 3 (a) and 3 (b), a two-bit mode indicator field would suffice to inform the receiver of the combination of the telephone call encoder and channel encoder used to process the data before transmission . Alternatively, the receiver may transmit a request for a particular codec mode to the transmitter or the receiver may transmit signal quality measures associated with the downlink channel (eg, BTS to the mobile station link) to the transmitter, which The transmitter then uses to identify an appropriate codee mode. In any of these three cases, some type of mode information is exchanged between the transmitter and the receiver over the air interface, whose phrase is used to include each of these three specific examples, as well as other types of mode information. In any case, since the mode information is also communicated on the air interface between the BTS 20 and the mobile station 12, it must also be protected against channel errors as well as data errors. However, it is not feasible since the mode information can be transported over the air interface using only a few bits per frame, efficient source coding (i.e. reduction of redundancy) with low delay. On the other hand, adding heavy channel coding, ie with a large amount of redundancy, is undesirable since it also adds to operational transmissions (ie, unusable load data) and reduces the user's effective bit rate. . It is also desirable to maintain a low coding delay so that codec modes can be changed quickly to account for rapid changes in transmission channel conditions. In accordance with exemplary embodiments of the present invention, therefore, the mode information is the encoded channel using a relatively weak channel code (i.e., a small amount of redundancy.) In Figure 3 (a), this is exemplified by the channel encoder 54 which employs a convolutional code rate 1 / C. In Figure 3 (b), this is exemplified by a block encoder 67 which employs block coding (8.2). More specific, though merely illustrative, examples of coding Relatively weak channel for the mode indicator are convolutional coding of velocity 1/3 to 1/2 (or greater) and block coding (4,2) to (8,2) (where, in each example, the first number within the parentheses is the number of ordinary bits and the second number is the number of net bits.) In order to appropriately decode, on the receiver side, the mode information which is conveyed over the air interface, which uses a relatively weak form of codi Channeling, exemplary embodiments of the present invention also employ probability calculations or composite possibility to assist in the appropriate decoding of information in a manner as illustrated in Figure 4. In that sense, an antenna 100 of the receiving apparatus, for example , receives radio signals on a certain radio channel. The signals (eg, data / telephone messages) transmitted on this channel can be strongly distorted, for example due to fading, so that TDMA bursts give rise to a highly distorted telephone call frame. The demodulation occurs in the radio receiver 102 at a given radio frequency (in the GSM system 865-935 MHZ) in a known manner, to obtain a modulated baseband signal. The resistance levels of the radio signals entering the radio receiver 102 can be measured and referenced as sm in the Figure. The baseband modulated signal is demodulated in the demodulator 104 within the IF range, this demodulator also includes an equalizer to compensate for or correct the multipath propagation to which the incoming signal has been subjected during transmission in a known manner. For example, the well-known Viterbi equalizer can be used for this purpose. The so-called flexible associated information with the probability of any given estimated symbol is obtained from the Viterbi equalizer in the demodulator 104, this flexible information is referred to as Sj in Figure 4. A deinterlacer 106 is connected downstream of the demodulator / equalizer 104 and recover the divided time bursts claimed by the receiver in a known manner. The receiver also includes an information probability processor 107 so that it calculates a composite probability associated with the value of the mode information and provides an output to the channel decoder 109 and the telephone call decoder 112, indicating the techniques identified by the receiver, such as those most likely used by the transmitter to initially process the block or frame data received. The composite probability includes, for example, a first probability parameter associated with the flexible information Sj generated during the demodulation process of the mode information and a second probability parameter generated by possibility or probability models 108. The first probability parameter can be a calculated metric along with, for example, the Viterbi decoding of the mode information. For each potential mode information value (for example, 00, 01, 10, 11, in example four in code mode above) the demodulation process can provide a first probability parameter. Similarly, the model 108 can also provide a second probability parameter value for each potential value of the mode information. The first and second probability parameter values associated with each potential value of the mode information may be combined, for example, multiplied together, to generate a composite probability for each potential value of the mode information and the highest possibility or probability may be selected for use by the channel decoder 109 and the telephone call decoder 112. The model employed in block 108 may vary depending on the various considerations of the system. For example, Markov models can be used as probability models for mode information. Markov models are, per se, well known in the art and, therefore, are not further described herein. However, the interested reader can obtain additional information regarding the Marcov models generally, and their use to provide estimates of the symbol values, in articles such as "Robust Speech Dedcoding: A Universal approach to Bit Error Concealment", authorized by Fingsdcheidt et al. and found in the Procedures of ICASSP'97, Munich, Germany, as well as "Robust GSM Speech Decoding Using the Channel Decoder's Soft Output", authorized by Fingsdcheidt et al. and found in the Procedures of Eurospeech '97, Rhodes, Greece, the descriptions of both articles are expressly incorporated herein by reference. For example, a Marcov model of order 0 is suitable for use as model 108 of information so if the codewords of mode codee is not distributed identically, that is, if all the possible codec modes to be used are not probably in a similar way for a given block or data frame of interest. More specifically, a Marcov model of order 0 is suitable for model 198 of information mode when a priori temporal knowledge does not influence the probability of a particular code mode. For example, if a certain block of data or block is received in time nl which has been processed with mode 1 and if this knowledge does not alter the relative probability whose code mode will be used by the transmitter to process the next block or frame of data, then a Marcov model of order 0 would be an appropriate choice for model 108. On the other hand, if codee mode used in time nl does not influence the probability of one or more codee modes being used at a subsequent time point , then a Marcov model of order 1 is suitable for the mode information model 108 to model the unequal transition probabilities from the codec mode codee procedure to the current one. The transition probabilities of the first order model can, for example, be established according to the following rules • Since mode changes are sometimes, the probability of switching from one code mode to another is small compared to the probability of maintenance in a current mode.

• Mode changes can only occur to adjacent modes, for example, if there were three different channel coding modes, it could only be permissible to switch from a heavier coding mode to a second channel coding mode more heavy, but not from the heavier channel coding mode to the weakest channel coding mode. In this way, transition probabilities for modes that are not direct neighbors can be set to 0. • More than n mode changes per timeslot of m frames can be prohibited. The probabilities of transition to other modes than the current mode then it can be set to 0 when the count n is exceeded within the time interval. • The entity that sends a codee request is aware of the required mode. Although there will be some delays until the request for the receiving entity, and the data of the telephone call is accordingly coded using the new source / channel coding combination and transmitted together with the indication accordingly, The decoder can deflect the transition probabilities of the Marcov model for the mode information to the value representing the required mode. • Channel conditions in uplink and downlink are correlated. Therefore, it is likely that the code mode request is received from the remote entity that corresponds to the code mode that is sent to the remote entity. The transition probabilities of the Marcov model for the codee mode request received by the first radio link (e.g., downlink) in this way can be diverted to the code mode required by the other link (e.g., uplink). Those skilled in the art will appreciate that these are merely examples of probabilistic models that can be used to determine a probability of the information so that it is a particular value for any given frame based on the rules and past history. On the other hand, whatever model is selected may itself be adapted due to changes in system configuration associated with other parameters, for example, changes in: • the number of codec modes; • resolution of link quality measures; • the rate of transmission of information in code mode (for example, for discontinuous transmission (DTX)); • degree of channel protection (i.e., amount of redundancy) of the codee mode information (eg, for DTX) • channel coding scheme (eg, convolutional or block coding) for the codee mode information ( for example for TDX) • of the architecture concept (whether symmetric or centralized control) of the two-way communication system. The last adjustment parameter refers to symmetric or centralized control architectures. Symmetric control architectures refer to systems where there is no distinction between the uplink and the downlink, that is, the mobile station and the base station are not distinguished. In this way, the transmitter for the link can control the selection of a mode. Alternatively, the mode requester, eg the receiver in a link, can control a mode (ie, the mode request and / or the measurements are attached to the transmitter). The centralized control architectures refer to scenarios where the system where the system is the master and the remote device, for example, the mobile station, is the slave. In this context, the system can control the code mode for both links, ie the mode requests by the mobile station is not linked. In this way, the type of architecture may reflect the likelihood of a particular mode being used for future data transmission, for example, the security with which a mobile station knows that its mode request will be distinguished by the system. On the other hand, with respect to other exemplary model setting parameters described above, those skilled in the art will recognize that during the DTX, a link is inactive and the codee mode information is transmitted at a reduced speed. For example, while the codec mode information is transmitted in each frame of the active link, more of the inactive link codee information is transmitted less frequently, eg, every sixth frame. Therefore it is likely that the information changes more frequently (by transmission) for the inactive link. As a consequence, the transition probabilities of the first-order Marcov model have to be adjusted to account for DTX in such a way that maintaining a current codee mode is less likely, while changing modes is more likely. Another possible model change associated with DTX can recognize that there is more available transmission capacity in a frame when DTX is being used, which in turn allows the strongest error correction coding to be used to protect the mode information. In the latter case, when the first probability parameter (from the flexible output channel decoding) is combined with the second probability parameter (from the probability model), the first one can be given more weight. In any case, once a composite probability is calculated for each possible value of the mode information and the most likely codee mode is identified, this provides the information necessary for decoding channel 109 and decoding telephone call 112 to operate using appropriate processing algorithms. For example, the main function of channel decoding 109 is to perform the opposite of the operation performed by the channel encoder on the transmitter side, ie, to retrieve the information transmitted from the known redundant bits and the known channel coding ( for example, a convolutional code). The decoded telephone call frames are delivered from the channel encoder 109 to the decode 112 of telephone call, telephone-frame call by telephone-frame call, by means of a flexible error concealment means 110. The flexible error concealment means 110 preferably is a state machine that is implemented in the software, and is responsible for handling situations where, for example, a telephone call frame is decoded erroneously. A complete synthesis of the received telephone call frames is performed in the telephone call decode 112 in order to supply telephone call signals to a sound reproduction unit 114 in the mobile station. Although the invention has been described in detail with reference to only some exemplary embodiments, those skilled in the art will appreciate that various modifications can be made without departing from the invention. Accordingly, only the invention is defined by the following claims which are intended to cover all equivalents thereof.

Claims (49)

1. CLAIMS 1. A method for communicating mode information between a transmitter and a receiver in a communication system comprising the steps of: providing at least two different codee modes for processing the information in the transmitter, wherein the mode information is associates with at least two different codee modes; coding, in the transmitter, mode information with an error protection coding having a predetermined level of redundancy associated therewith; transmit the information in coded mode over an air interface; decoding, in the receiver, the encoded mode information using a flexible output channel decoding process to generate a first probability parameter for each different potential value associated with the mode information; evaluating, in the receiver, a probability model associated with the mode information to generate a second probability parameter for each different potential value associated with the mode information, and selecting one of the different potential values for the received mode information in the first and second probability parameters.
2. 2. The method of claim 1, wherein the step of selecting further comprises: combining, at the receiver, the first and second probability parameters, and selecting one of the different potential values having a higher combined probability.
3. The method of claim 1, wherein the decoding step further comprises the steps of: encoding -convolutionally the mode information.
4. The method of claim 3, wherein the step of convolutionally encoding the mode information further comprises the step of convolutionally encoding the mode information in a ratio greater than or equal to 1/3.
5. The method of claim 1, wherein the step of encoding the mode information further comprises the step of: encoding the mode information en bloc.
6. The method of claim 5, wherein the step of en bloc encoding the information in mode further comprises the step of: enblocking the mode information using a block code of 4.2 to 8.2.
7. The method of claim 1, wherein the mode information is an indicator that identifies one of at least two different different codec modes that is used to process data that is transmitted by the transmitter.
8. The method of claim 1, wherein each of at least two code mode modes identifies a source coding technique and a channel coding technique.
9. The method of claim 1, wherein the mode information is a request for one of at least two of the different codee modes.
10. The method of claim 1, wherein the mode information is the channel measurement information that can be used by the receiver to determine an appropriate one of at least two different code modes.
11. The method of claim 1, further comprising the step of: adjusting the probability model based on a change in a number of at least two different codee modes.
12. The method of claim 1, further comprising the step of: adjusting the probability model based on a change in resolution of the channel quality measurements associated with the transmission of information on the air interface between the transmitter and the receiver.
13. 13. The method of claim 1, further comprising the step of: adjusting the probability model based on a change in the proportion of mode information.
14. The method of claim 1, further comprising the step of: adjusting the probability model based on a change in the predetermined level of redundancy of the error protection coding.
15. 15. The method of claim 1, further comprising the step of: adjusting the probability model based on a change in a coding scheme used by the mode information.
16. 16. The method of claim 1, also includes the stage of: adjusting the probability model based on a change associated with the discontinuous transmission.
17. 17. The method of claim 1, wherein the communication system is a two-way communication system.
18. 18. The method of claim 1, further comprising the step of: adjusting the probability model based on a change in an architecture of the two-way communication system.
19. 19. The method of claim 1, wherein the communication system is a one-way communication system.
20. The method of claim 1, wherein the probability model is a zero-order Markov model that has probabilities that reflect a distribution of mode information. _ twenty-one .
21. The method of claim 1, wherein the probability model is a Markov model of order one having the probabilities that reflect a transition of mode information.
22. 22. The method of claim 17, further comprising: adjusting the probability model based on the knowledge of one required from at least two different codee modes.
23. The method of claim 17, further comprising the step of: adjusting the probability model for a link between the transmitter and the receiver based on the knowledge of one of at least two different codee modes that is currently employed in another link to transmit the information from the receiver to the transmitter.
24. 24. A communication system that includes a transmitter and a receiver that communicates the mode information between them comprises: means for providing at least two different codee modes for processing the information in the transmitter, wherein the mode information is associated with at least two different codeine modes; means for encoding, in the transmitter, the mode information with an error protection having a predetermined level of redundancy associated therewith; means for transmitting the information in coded mode on an air interface; means for decoding, in the receiver, the encoded mode information using means for a flexible output channel decoding process to generate a first probability parameter for each different potential value associated with the mode information; means for evaluating, in the receiver, a probability model associated with the mode information to generate a second probability parameter for each different potential value associated with the mode information, and means for selecting one of the different potential values for the information received mode based on the first and second probability parameters.
25. 25. The method system of claim 24, wherein the means for selecting further comprises: means for combining, at the receiver, the first and second probability parameters, and means for selecting one of the different potential values that has a probability. combined higher.
26. 26. The system of 24, wherein the means further comprise: means for convolutionally encoding the mode information.
27. The system of claim 26, wherein the means for convolutionally coding the mode information further comprises: means for convolutionally encoding the mode information into a ratio greater than or equal to 1/3.
28. The system of claim 24, wherein the means for encoding the mode information further comprises: means for encoding the mode information en bloc.
29. 29. The system of claim 28, wherein the means for en bloc encoding the mode information further comprises: block coding the mode information using a block code of 4.2 to 8.2.
30. 30. The system of claim 24, wherein the mode information is an indicator that identifies one of at least two different codec modes that is used to process data being transmitted by the transmitter.
31. The system of claim 24, wherein each of at least two code mode modes identifies a source coding technique and a channel coding technique.
32. 32. The system of claim 24, wherein the mode information is a request for one of at least two different codee modes.
33. The system of claim 24, wherein the mode information is the channel measurement information that can be used by the receiver to determine an appropriate one of at least two different code modes.
34. 34. The system of claim 24, further comprising: means for adjusting the probability model based on a change in a number of at least two different codee modes.
35. 35. The system of claim 24, further comprising: means for adjusting the probability model based on a change in the resolution of the channel quality measurements associated with the transmission of information on the air interface between the transmitter and the receiver.
36. 36. The system of claim 24, further comprising: means for adjusting the probability model based on a change of a mode information proportion.
37. 37. The system of claim 24, further comprising: means for adjusting the probability model based on a change in the predetermined level of redundancy of the error protection coding.
38. 38. The system of claim 24, further comprising: means for adjusting the probability model based on a change in a coding scheme used for the mode information.
39. 39. The system of claim 24, further comprising: means for adjusting the probability model based on a change associated with discontinuous transmission.
40. 40. The system of claim 24, wherein the communication system is a two-way communication system
41. 41. The system of claim 40 further comprises: means for adjusting the probability model based on a change in an architecture of the Two-way communication system.
42. 42. The system of claim 24, wherein one-way communication system.
43. 43. The system of claim 24, wherein the probability model is a Markov model of a zero order that has probabilities that reflect a distribution of the information mode.
44. 44. The system of claim 24, wherein the probability model is a Markov model of order of one that has probabilities that reflect a transition of the mode information.
45. 45. The system of claim 40, further comprising: means for adjusting the probability model based on the knowledge of one required from one of at least two different codee modes.
46. 46. The system of claim 40, further comprising: means for adjusting the probability model for a link between the transmitter and the receiver based on the knowledge of one of at least two different codee modes that is currently employed in another link for transmit the information from the receiver to the transmitter.
47. 47. A method for decoding the information so that it comprises the steps of: decoding the mode information to obtain a first probability parameter associated with a value of the mode information; evaluate a probability model to obtain a second probability parameter associated with the value of the mode information; and selecting a final value for the mode information based on the first and second probability parameters.
48. 48. The method of claim 47, wherein the probability model is a zero-order Markov model that has probabilities that reflect a distribution of mode information.
49. 49. The method of claim 47, wherein the probability model is a Markov model of order one having probabilities that reflect a transmission of the mode information.