Arq with adaptive modulation for communication systems

The principles of the present application relate to communication systems.

Layered coding systems are generally known and are used throughout the telecommunications industry. An example of such a layered coding system is the MIMO (Multiple Input, Multiple Output) architecture. These multi-antenna systems improve spectral efficiency through the use of spatial multiplexing.

A MIMO system is a system in which a plurality of transmitting antennas and a plurality of receiving antennas are used. MIMO systems can generally achieve higher capacitance in high-scattering environments than SISO (single input single output) systems. Various techniques can be used to achieve MIMO functionality: spatiotemporal codes can be applied to multiple transmitting antennas across multiple channel uses; layer structures can also be applied where only one-dimensional codes are applied to each layer. Examples of layered structures are V-BLAST and D-BLAST proposed by Nokia Bell Labs. In V-BLAST, independently encoded data streams are sent through different transmitting antennas. Therefore, in V-BLAST, the layer represents one antenna. In D-BLAST, the data stream / antenna association is cycled cyclically.

In general, layer architecture means any interleaving method in which different antennas belong to different layers at any given time and each antenna index belongs to only one layer at any given time. A layer is an index of the antenna as a function of time. The layer structure is shown in Figure 1 for illustrative purposes. Here, layer 1 from time index 1 to 7 is represented by antenna index 3,2,1,3,2,1,3.

<p> According to some general aspect of the principles of the present application, the method sends codeword encoded with a rateless code, monitors a predetermined time period, and is absent based on the expiration of the time period. Includes sending subsequent codewords encoded with a rate code.</p><p> According to another aspect of the principles of the present application, the device allows the transmission of codewords encoded in a rateless code with a timer that monitors a predetermined time period, based on the expiration of the predetermined time period. Includes a controller that forces the transmission of subsequent codewords encoded with the unrated code.</p><p> According to another aspect, the method received a codeword encoded with no rate code and occurred either before the successful reception of the received codeword or the expiration of a predetermined time period. Includes sending an indication signal in response.</p><p> In yet another aspect, the device sends a timer that monitors a predetermined time period and a controller that sends an indicator signal indicating either the expiration of the predetermined time period or the successful reception of codeword encoded with no rate code. And include.</p><p> Details of one or more implementations are provided in the accompanying drawings and in the description below. Further features will be apparent from the description and drawings, and from the claims.</p><p> In the drawings, similar reference numerals indicate similar components throughout the drawings.</p>

<figref num="1">It is a figure which shows the communication structure in the layer structure which shows the index of an antenna as a function of time.</figref><figref num="2">It is a block diagram of a communication system based on a certain aspect of the principle of this application.</figref><figref num="3">It is a more detailed block diagram of an exemplary MIMO communication system that can incorporate the principles of the present application.</figref><figref num="4">It is a flow chart of the method based on a certain aspect of the principle of this application.</figref><figref num="5a">It is a flow chart of the method based on another aspect of the principle of this application.</figref><figref num="5b">It is a flow chart of the method based on another aspect of the principle of this application.</figref><figref num="5c">It is a flow chart of the method based on another aspect of the principle of this application.</figref><figref num="6">It is a block diagram of the apparatus based on a certain aspect of the principle of this application.</figref><figref num="7">It is a flow chart of the method based on another aspect of the principle of this application.</figref><figref num="8">It is a block diagram of the apparatus based on the further aspect of the principle of this application.</figref><figref num="9">It is a block diagram of the apparatus based on the further aspect of the principle of this application.</figref><figref num="10">It is a flow chart of the method based on the further aspect of the principle of this application.</figref><figref num="11">It is a flow chart of the method based on another aspect of the principle of this application.</figref><figref num="11a">It is a flow chart of the method based on another aspect of the principle of this application.</figref><figref num="12a">It is a flow chart of the method based on a certain aspect of the principle of this application.</figref><figref num="12b">It is a flow chart of the method based on another aspect of the principle of this application.</figref><figref num="13">It is a flow chart of the method based on another aspect of the principle of this application.</figref><figref num="14">It is a block diagram of a decoder based on a certain aspect of the principle of this application.</figref><figref num="15a">FIG. 5 illustrates an exemplary transmission using concatenated coding based on a further aspect of the principles of the present application.</figref><figref num="15b">FIG. 5 illustrates exemplary reception using concatenated coding based on another aspect of the principles of the present application.</figref><figref num="16">It is a flow chart of the method using the concatenation code on the transmitter side of the communication system based on the implementation based on the principle of this application.</figref><figref num="17">It is a flow chart of the method using the concatenation code on the transmitter side of the communication system based on the further implementation of the principle of this application.</figref><figref num="18">It is a flow chart of the method using the concatenation code on the receiver side of the communication system based on the implementation based on the principle of this application.</figref><figref num="19">It is a flow chart of the method using the concatenation code on the receiver side of the communication system based on the further implementation of the principle of this application.</figref><figref num="20">It is a block diagram of the apparatus based on a certain aspect of the principle of this application.</figref><figref num="21">It is a flow chart of the method of modifying a modulation method based on a certain aspect of the principle of this application.</figref><figref num="22">It is a flow chart of the method of modifying a modulation scheme based on another aspect of the principle of the present application.</figref><figref num="23">It is a block diagram of the apparatus which modifies the modulation scheme based on some aspect of the principle of this application.</figref><figref num="24">It is a flow chart of the method of modifying a modulation scheme based on a further aspect of the principle of the present application.</figref><figref num="25">It is a flow chart of the method of modifying a modulation scheme based on another aspect of the principle of the present application.</figref><figref num="26">It is a flow chart of the method of modifying a modulation scheme based on another aspect of the principle of the present application.</figref><figref num="27">It is a flow chart of the method of modifying a modulation scheme based on another aspect of the principle of the present application.</figref><figref num="28">It is a flow chart of the method of modifying a modulation scheme based on a further aspect of the principle of the present application.</figref><figref num="29">It is a flow chart of the method of modifying a modulation scheme based on another aspect of the principle of the present application.</figref><figref num="30">It is a block diagram of the apparatus which modifies the modulation scheme based on another aspect of the principle of this application.</figref><figref num="31">It is a flow chart of the method of modifying a modulation scheme based on another aspect of the principle of the present application.</figref><figref num="32">It is a flow chart of the method of modifying a modulation scheme based on another aspect of the principle of the present application.</figref><figref num="33">It is a flow chart of the method of modifying a modulation scheme based on another aspect of the principle of the present application.</figref><figref num="34">It is a flow chart of the method of modifying a modulation scheme based on another aspect of the principle of the present application.</figref>

In layered MIMO systems, such as the V-BLAST or D-BLAST architecture, unrate codes can be used across subchannels to provide error correction. In such a system, codewords can be decoded when sufficient information is received. Channel conditions, such as the signal-to-noise ratio (SNR), are monitored to determine when sufficient information is received. Mutual information is a function of SNR. The maximum transmission rate can be determined by averaging the amount of mutual information over time. One problem is that under poor conditions, the time required to accumulate enough mutual information to decode codewords can be long, creating real-time constraints such as streaming video. The system that has it suffers disproportionate delays and errors.

According to the principled implementation of the present application, the transmission of subsequent codewords encoded with no rate code can be timing based. Alternatively, the SNR information and the correspondingly stored lookup table can be used to obtain the capacity value of the communication layer to avoid over-estimation of the amount of mutual information received. ..

2 and 3 show transmitter 102 and receiver 104 of a communication system that implement various concepts of the principles of the present application. As an example, FIG. 3 shows a V-BLAST communication system showing a transmitter (ie, an encoder) having an input multiplexer 106 and a plurality of channel encoders 108, each having its own antenna 109. The receiver 104 includes a decoder 110 and an output multiplexer 112. Those skilled in the art have disclosed the communication systems of FIGS. 2 and 3 solely for illustrative purposes in this article, and to any communication system having any layered configuration in which the principles of the present application utilize rate-free codes (eg, You will recognize that it can be applied to any MIMO system. For example, transmitters and receivers can each be replaced by transceivers, depending on the particular application. Those skilled in the art will recognize that the modulator contained within the transmitter 102 and the demodulator contained within the receiver 104 are not shown in FIG. 3 for simplicity.

With reference to FIG. 4, according to some implementation of the principles of the present application, codewords are encoded and transmitted with no rate code (402). The time period is monitored upon transmission or at substantially the same time as the transmission (404). The time period is generally predetermined and has a length that allows the transmitter to assume that the transmitted codeword has been successfully received by the receiver. Those skilled in the art will recognize that this time period can be established and monitored in many different ways, without departing from the spirit of the principles of the present application. For example, a time period uses a processor or other computing medium, a clock with a timing flag or other indicator, and possibly maintains a separate timer for each predetermined time period. Can be established and monitored through the use of setting interrupts.

Throughout the time period, the transmitter determines if an indicator signal in the form of an acknowledgment signal (ACK) has been received (406). If the indicator signal ACK has been received during the time period, the next codeword is transmitted (410).

If no indicator signal ACK has been received during the time period, the system proceeds as if an erase flag had been received (408), forcing the subsequent transmission of the next codeword (40). 410). The erase flag does not necessarily have to be received by the transmitter, but by forcing the transmitter to follow a time period for codeword transmission, the system's real-time constraints or requirements can still be met.

Figure 5a shows another implementation of the principles of the present application, where the erase flag is embodied in the form of a negative acknowledge NACK. Thus, when the time period expires (504), the next codeword is transmitted, regardless of whether the indicator signal has been received (510). If an index signal is received during the time period, it is determined whether the index is an acknowledgment ACK or a negative receipt confirmation NACK (506).

According to various implementations, the acknowledgment ACK can be an indicator that the transmitted codeword was successfully received, or that it was successfully received and successfully decoded. Negative receipt confirmation NACK can be an indicator that the transmitted codeword may be unreliable or may not be completely decoded. When the NACK is identified, the transmitter modifies the subsequent modulation scheme used to transmit the next codeword (510). In one implementation, NACK acts to notify the transmitter that the current modulation scheme is not working on the decoder side, and the transmitter responds by modifying the modulation scheme for subsequent transmissions.

According to another implementation shown in Figure 5b, the transmitter can monitor or count the number of NACKs received during a given time period of 505 (514). This predetermined time period 505 is generally longer than the predetermined time period 504 and is selected to ensure that the channel is really bad (for NACK) or really good (for ACK-see Figure 5c). If the number of NACKs received is greater than or equal to the number of NACKs received during a given time period of 505 (516), the transmitter does not require further information from the receiver (eg, modulation). It can respond by lowering the order of modulation (for example, from 16-QAM to QPSK) and sending the next codeword accordingly, without requiring a correction index or the like).

Conversely, if the number of ACKs received is greater than or equal to the number of ACKs received during the given time period 505, as shown in FIG. 5c (522), then the transmitter has the following codeword: It can be responsive by increasing the order of modulation prior to transmission 510 (eg, from QPSK to 16-QAM). The implementations of FIGS. 5b and 5c may also continue to transmit additional codewords while accumulating and counting ACKs and / or NACKs.

FIG. 6 is a diagram showing a transmitter 102 based on the principled implementation of the present application. The transmitter 102 includes a controller 600, a processor 602 and at least one memory / data storage device 608. Processor 602 includes an onboard clock or timer 604 that can be used in many different ways to provide timer functionality for various principles of the present application, as described above. According to various implementations, the controller 600 is an application specific integrated circuit (ASIC), a processor programmed to function according to one or more of the principles of the present application, or to operate according to one or more of the principles of the present application. It can be any combination of required logic or integrated circuit design. The memory 608 can be embodied in many different forms without departing from the spirit of the principles of the present application. For example, memory 608 can be ROM, RAM, removable disk media, hard drives, flash memory or any other suitable storage device.

FIG. 7 shows a flow diagram of Method 700 for receiving codewords encoded with no rate code. As shown, codewords encoded with no rate code are received (702). The action of receiving the unrate-encoded codeword 702 is a progressive action. During reception, the time period is monitored (704) to determine if the time period has expired. Prior to the expiration of the time period, the codeword is successfully received (repeated if necessary) to determine if it has been decoded (706). If so, an indicator signal is sent (708) that provides a positive indicator that the codeword has been successfully received and decoded, and the subsequent codeword is received.

When the time period expires in step 704 and it is not confirmed that the codeword was successfully received and decrypted (step 706), the receiver receives an indicator signal to allow the subsequent reception of the codeword 710. Forcibly send 708. As described above, the index signal in this example may include an erasure flag, or may have one embodied in the negative receipt confirmation (NACK). It is used to notify the source of the received data to modify the modulation scheme used for subsequent transmissions.

According to one implementation, the (708) indicator signal sent can include a modulation correction index or other modulation modification instructions for the source of the encoded codeword. This is especially true when the encoded codeword is not received well and / or is poorly decoded (for example, when a NACK signal is generated and returned to the source of the received data). As mentioned above, a modulation correction index or other modulation method correction instruction can be a positive increase in modulation order when it is confirmed that reception and / or decoding has been successful multiple times within a given time period. it can.

FIG. 8 shows a block diagram of a portion of the decoder 110 and the components of the decoder 110. The decoder 110 includes a receiver 800, a controller 802, a processor 804, at least one form of memory / data storage device 806 and a clock 808. As mentioned above with reference to FIG. 7, the decoder 110 receives the encoded codeword and responds to either positive or negative reception conditions by sending an indicator signal to the source of the encoded codeword. provide. Positive reception conditions include, in one implementation, the successful reception of the encoded codeword, and in another implementation, both the successful reception and decoding of the received encoded codeword. Negative reception conditions indicate that in one implementation the received data is considered unreliable and may not be decoded, in another implementation a negative reception condition means that the received data is undecoded. Show that it is identified as possible.

As mentioned above, during communication in a layered MIMO system, the calculated mutual information (using the unconstrained channel capacity formula) is much larger than the actual mutual information obtained at the receiver. There can be. This is especially true when common modulation schemes such as QPSK or 16-QAM are used in the system. This is an overestimation of mutual information, which has a negative impact on subsequent transmissions.

To overcome this problem and avoid overestimating the amount of mutual information obtained at the receiver, the actual capacitance formula for modulation is used at each layer. For example, when SNR = 5db, the capacitance for QPSK modulation is 1.7 bits / symbol. If there is no closed-form capacitance formula (for example, there is no closed-form capacitance formula for 16-QAM modulation), or if the capacitance calculation is complicated (for example, it takes too much processing time), the layer in the communication system / Look-up tables can be used to obtain the amount of mutual information received based on a determined quality measure of the channel and the type of modulation used. According to one implementation, the quality metric is the signal-to-noise ratio (SNR) at the layer. In addition, look-up tables (LUTs) can also be used to obtain the optimum modulation format supported by the communication channel based on a determined quality metric for the layer / channel in the communication system.

With reference to FIGS. 9 and 10, a decoder 110 based on a further implementation of the principles of the present application is shown. The controller 900 of this decoder is configured to receive codewords encoded with no rate code (1002). With no-rate codes, only finite lengths are transmitted or received, but codewords may be defined as having an infinite length. Throughout this application, the term codeword is often used to refer to the part of an infinite length of "codeword" that is actually transmitted or received. Processor 902 is configured to calculate the quality measure of the communication medium on which the codeword is transmitted. Memory 904 stores lookup table (LUT) data that can be used to determine the optimal modulation format supported by the channel. The type of LUT data will include different LUTs for each of the individual modulation schemes known to be used in a particular communication system. Some examples of such modulation schemes include, but are not limited to, BPSK, QPSK and 16-QAM.

The calculated quality metric is used, for example, using processor 902 to determine the optimal modulation format supported by the communication system (1006). Once determined, the controller of the decoder is configured to receive subsequent codewords based on the modified modulation scheme. The modified modulation scheme was derived from a determined optimal modulation format that is supported by the communication medium and can be used to send data through the communication medium (1008).

According to the additional implementation 1100 shown in Figure 11, after receiving the codeword (1102), the decoder identifies the modulation scheme used by the source of the received data (1104). Quality metric for the communication channel is then calculated using, for example, a processor (1106). The calculated quality metric (eg, channel or layer SNR) and known modulation schemes are used to access memory 904 to obtain LUT values that correspond to the known modulation schemes. The optimal modulation format supported by the communication medium is determined (1108). The optimal modulation format can be determined, for example, by a processor that determines which modulation format LUT provides the best expected capacitance in a calculated quality metric. If the determined optimal modulation format differs from the current modulation scheme (or has a sufficiently large difference to justify the switch), the optimal modulation scheme is identified as the new modulation scheme. A "hysteresis" value can be used to avoid the ping-pong switching effect. The new modulation scheme is fed back to the source of the transmitted data (1110). The source is expected to send subsequent codewords using the fed-back modified modulation scheme. Subsequent encoded codewords are received using the fed-back modified modulation scheme (1112). Of course, the "optimal" format does not have to be global optimization, and many implementations determine formats that improve performance (but do not necessarily need to be optimized).

With reference to FIG. 11a, method 1115 is shown. In various implementations, LUTs are also used to determine the amount of mutual information being received. Method 1115 is an example of such an implementation. Method 1115 involves receiving data encoded with no rate code (1002) and determining quality metrics (eg SNR) for the channel (1004). Quality metric can be determined, for example, by calculating a metric, receiving a metric from another device, or accessing a metric from storage. The modulation scheme used to transmit the received encoded data is identified (1104).

Method 1115 further includes determining an estimate based on the identified modulation scheme / format and the determined quality metric, an estimate of the amount of mutual information received per unit of encoded data received. .. Estimates can be determined in a variety of ways, for example using closed-form capacitance equations. Method 1115 presents another implementation for non-closed-form capacitive equations that can provide improved speed.

Method 1115 further accesses a particular LUT based on the identified modulation scheme / format and determined quality metric (1120) and the amount of mutual information received per unit of encoded data 1130 received. Includes accessing an entry in the particular LUT that provides an estimate of. Method 1115 further comprises determining the amount of mutual information received based on the accessed entry (1140). In one implementation, a LUT is a one-dimensional table (eg, a list) that contains mutual information about a given modulation format, with each entry corresponding to a different SNR. In another implementation, the LUT is a two-dimensional table (rows correspond to modulation formats, columns correspond to SNRs, and entries correspond to mutual information indicators for specific rows (modulation formats) and columns (SNRs). For example, matrix). The mutual information indicator (LUT entry) can be determined, for example, based on the identified modulation scheme and the capacitance formula corresponding to the SNR. This use of the LUT may be performed without the use of other concepts and aspects described herein, or may be used in connection with one or more other concepts and aspects.

In MIMO and other communication systems, capacitance calculations are performed to calculate the mutual information received, but unfortunately it is typically only an approximation and accurate in the time limit over time. Is. Thus, in practice, it may still be insufficient to decode codewords, even when the overall amount of mutual information received is declared sufficient for decoding by the receiver. sell.

According to some aspect of the principles of the present application, this deficiency goes beyond what is considered the usual amount to allow accurate decoding of received codewords, and the accumulation of additional mutual information in the receiver. Is dealt with by enabling. The accumulation of additional mutual information provides a higher probability of successful decoding.

Thus, with reference to FIGS. 12a and 12b, Method 1200 with the principled implementation of the present application is shown. First, data is received for data blocks encoded with no rate code (1202). It is then determined whether an initial predetermined amount of mutual information (MI) about the data block has been received by the receiver (1203). This "initial predetermined amount" is an amount believed to be sufficient to allow the receiver to successfully decode the received codeword. Those skilled in the art will recognize that this "initial predetermined amount" can be different for each communication system and incorporates all known communication media variables such as noise.

Once an "initial predetermined amount" of mutual information is received, additional encoded data about the data block is received (1204), exceeding the initial predetermined amount and mutual about the data block. Another determination is made as to whether an excess amount of information has been received (1205). Once an additional or "excessive amount" of mutual information has been accumulated, the receiver decodes the received codeword (1206) and then the MI and encoded codeword for the next received transmission. Continue to receive. Codeword decoding 1206 is performed in this implementation using only an initial predetermined amount of encoded data. In another implementation, as shown in Figure 12b, decoding 1206 can be performed with both initially received encoded data and additionally received encoded data (1208). By using the excess accumulated MI associated with the excess / additional encoded data (1204) for the data block, the probability of successful decoding by the receiver is increased.

Those skilled in the art will recognize that the actual amount of "excess predetermined amount" can vary from communication system to communication system without departing from the spirit of the principles of the present application.

According to another implementation, the initial mutual information and the amount of excess mutual information accumulated can be time-based. For example, with reference to FIG. 13, a method 1300 based on another implementation of the principles of the present application is shown. Encoded data is received for unrate-coded encoded data blocks, as shown in the figure (1302). A determination is then made as to whether an initial predetermined amount of MI associated with the encoded data has been received (1304). This determination 1304 can be based on, for example, a time period or a capacity formula of the communication medium. In addition, a lookup table containing estimates of mutual information per unit of received data based on capacitance formulas for a given modulation and signal-to-noise ratio may be used. When the decoder determines that an initial predetermined amount of MI has been received (due to expiration of a time period or otherwise), the receiver begins accumulating (receiving) additional encoded data for that data block (due to expiration of time period or otherwise). 1306). The receiver accumulates additional or excess encoded data and the corresponding MI until an excess predetermined amount of MI is received (1308). The determination for an excess predetermined amount of MI can be based on any other known method for determining the time, bit length, or expected amount of data received. If it is determined that an excess predetermined amount of MI has been received, the codeword is decoded (1310) and the receiver / decoder can go back to the beginning and start receiving the next transmission of the encoded codeword.

As mentioned above, the first predetermined time period is long enough to allow or tolerate the decoder to successfully receive and decode the encoded codeword. This first predetermined time period may differ for different communication systems and different modulation techniques used by such systems. Implementations may combine two timers into a single timer.

FIG. 14 shows a decoder 1400 based on the principled implementation of the present application. This decoder includes a controller 1402 configured to receive mutual information (the amount of mutual information is calculated based on the encoded codeword received or other received data). Through the application of processor 1404 and memory 1406, the controller is further configured to receive both an initial predetermined amount of mutual information and an excess or additional predetermined amount of mutual information. In some implementations, the decoder 1400 may include a receiver 1410 adapted to receive mutual information.

According to the principles of the present application, excess or additional mutual information accumulation can provide improved reliability, which typically involves reduced data rates due to the added information. Is accompanied by a trade-off. In addition, the accumulation of additional or excess mutual information leads to longer codewords that the decoder should decode, and thus generally leads to higher decoding complexity. While these trade-offs are acceptable for many applications, some implementations are coded given the increased decoding complexity and / or reduced data rates resulting from the accumulation of additional mutual information. For words, use concatenated coding where the outer code is a block code, such as a read solomon or BCH code, and the inner code is a non-rate code.

In one such implementation, using the (N, K) outer block code, K information bits are first encoded into codewords of length N bits. Each codeword is broken down into smaller sized subblocks. For example, an N-bit codeword can be decomposed into four subblocks, each with a length of N / 4 bits. The inner unrate code applies to each subblock of the codeword. Unrate code because it is expected that the size of the unrate codeword required for successful decoding will be smaller by decomposing the block codeword into subblocks prior to encoding with the inner unrate code. The complexity of word decoding can be reduced. Alternatively, the outer block code can be made larger by decomposing the codeword into subblocks prior to encoding with no rate code, which is achieved using several smaller block codes serially. More error correction can be provided for a given number of parity bits. In addition, larger block codes provide better burst error correction, for example, by correcting bursts that smaller block codes cannot correct compared to smaller block codes. Moreover, at least some of the advantages of larger block codes and smaller unrate codes can be achieved together in the same implementation.

15a and 15b show diagrams of configurations for transmission and reception of codewords encoded with inner unrate codes, respectively, based on the principled implementation of the present application. As shown in Figure 15a, the transmitter / encoder sequence is input to the outer encoder 1502. The outer encoder 1502 encodes a block of the input data sequence into the codeword given at the output of the encoder 1502. The divider 1503 divides the data block output into subblocks, and the inner encoder 1504 encodes the subblocks with no rate code. The encoded transmission sequence is input to the modulator 1506, modulated and transmitted over the antenna. Figure 15b shows the receiver / decoder side. Here, the demodulator 1508 receives the modulated signal and demodulates the received modulated signal. The inner unrate code decoder 1510 first decodes the unrate code of the subblock to determine the subblock, then the combiner 1511 combines the subblock with the outer codeword, and the outer codeword is passed to the outer decoder 1512. Residual errors are further removed and decoding is cleaned up. The combination 1511 and the divider 1503 can be implemented, for example, in software and / or hardware. Some software implementations use registers and appropriate instructions, and some hardware implementations use shift registers and appropriate logic.

FIG. 16 shows a method 1600 for sending encoded data, based on another implementation of the principles of the present application. The data is accessed (1602), an outer block code is generated for that data (1604), and the outer block codeword is decomposed into subblocks (1606). Once subdivided, subblock codewords are encoded using unrate code (1608). Once encoded with unrate code, the unrate codeword for the subblock is sent to the receiver (1610).

According to one further implementation, Method 1700 generates an outer block codeword for an input block of data (1710) and determines an inner unrated codeword for a subblock of the outer block codeword (1720). Method 1700 then begins sending a predetermined amount of unrated codeword (1730). After the first time period expires (1740), it is assumed that a given amount has been sent, and Method 1700 begins sending a second given amount of unrated codeword (1750). It is assumed that after the expiration of the second time period (1750), the second prescribed amount was sent. Method 1700 can be repeated to send unrated codewords for each subblock. Further, in the implementation, both timers may be combined.

18-20 show another implementation of the principles of the present application on the receiver side. Referring to FIG. 18, the receiver begins by receiving a predetermined amount of mutual information about codewords encoded in a concatenated code (1802). Once a predetermined amount has been received, the receiver continues to accumulate or receive an excess amount of mutual information in excess of the predetermined amount. Once excess mutual information is received, the receiver is configured to decode the concatenated codeword (1806) by first decoding the inner unrated code to determine the subblock. Once the inner unrate code is decoded, the subblocks are combined to unravel the block codeword (1808). Once the block codeword is clarified, the outer code is decoded (1810) to clean up residual errors.

FIG. 19 shows another implementation in which a timer is established by the receiver to determine that sufficient information has been received. In this example, the receiver begins to receive a predetermined amount of mutual information about the codeword encoded by the concatenated code (1902). The first predetermined time period 1903 is monitored for its expiration. The receiver continues to receive a predetermined amount of mutual information until the expiration of the first predetermined time period. Upon expiration of the first predetermined time period, the receiver receives (accumulates) "excess" or additional mutual information (1904). This accumulation of excess mutual information is carried out over a second predetermined time period (1905). Upon expiration of this second time period, the codeword is decoded by first decoding the inner unrate code to determine the subblocks of the block codeword (1906). Subblocks are then combined to elucidate the block codeword (1907). Once combined, the outer block code is decoded (1908) to clean up residual errors.

FIG. 20 shows a block diagram of the decoder 2000 based on the principled implementation of the present application. As shown, the decoder 2000 includes controller 2002, processor 2004 and memory 2006. Controller 2002 is configured to receive codewords encoded through receiver 2010, which provide mutual information. Processor 2004 includes clock 2008 and can be programmed to establish all the time periods required to receive mutual information. Memory 2006 is part of Decoder 2000 and contains information such as the time period or interval required for mutual information receipt, depending on, for example, the modulation scheme used to transmit the encoded data. be able to. The decoder 2000 is further configured to decode the inner unrate code of each subblock so that the subblocks can be combined to elucidate the codeword. After the codeword is clarified by the combination of the inner unrate code decoding and the subblock, the outer code decoding is executed.

Those skilled in the art will appreciate that the controller and processor can be configured separately to function together, or be embodied in a single device with the corresponding programs and logic to function as described herein. You will recognize that you can also.

The use of receipt confirmation signals in layered communication systems using unrate codes has various advantages as discussed above. In particular, receipt confirmations can be sent as soon as sufficient mutual information is deemed to have been received. However, although valuable, the transmission of such receipt confirmations may not take full advantage of the communication channel (eg, do not utilize the full capacity of the channel to increase the data rate). There can be).

As an example, when the modulation on each channel is BPSK or QPSK, the channel can support higher order modulation (eg 16-QAM), which in turn supports higher data rates. become.

There are several ways to determine if such a modulation scheme modification is possible. The implementation illustrated and described with reference to FIGS. 21-34 is for illustrative purposes and illustrates the use of communication quality determination. Those skilled in the art will recognize that other methods and / or implementations of the same concept can be made without departing from the spirit of the principles of the present application.

With reference to FIG. 21, a method 2100 based on the principled implementation of the present application is shown. First, information related to the quality of communication through the at least one communication channel is accessed (2102). Based on the accessed information, an index is given as to the modulation scheme to be used to send unrate code encoded data through the channel (2104). In this example, the information related to the quality of the communication channel can be the frequency of occurrence of the indicator signal within a predetermined time period or a predetermined time period.

FIG. 22 shows a modified implementation of the method of FIG. In this method 2200, information related to the quality of communication through the at least one communication channel is accessed (2202) and the index signal is identified. At the onset of said access, a time period is established (2208). During that time period, the number or frequency of occurrences of the identified indicator signal is counted (2206). At the end of the time period, a modulation scheme is indicated for transmitting subsequent data in response to and based on the quality-related accessed information (2204). The length of the predetermined time period 2208 can be any suitable time length based on, for example, the current modulation scheme used, the time period estimated based on the expected results, and so on.

FIG. 23 shows a device 2300 based on the principled implementation of the present application. The device includes a controller 2302, a processor 2304 with a clock 2306, a memory 2308 and a connection to a bidirectional communication channel 2310. As discussed above, the quality of communication through communication channel 2310 is determined and used to indicate the modulation scheme to be used for the channel. In this way, controller 2302 accesses information related to the quality of communication channel 2310. Processor 2304 is configured to use the accessed quality information to provide a modified modulation scheme index for subsequent transmission of unrate code encoded data through communication channel 2310.

As an example, processor 2304 is shown as having clock 2306. Those skilled in the art will recognize that the clock 2306 can be implemented in many different ways without departing from the spirit of the principles of the present application. For the purposes of this example, clock 2306 can be used to establish a predetermined time period. During that predetermined time period, controller 2302 accesses information related to the quality of communication channel 2310. In this way, monitoring of communication quality through channel 2310 can be limited to a preset time period or a predetermined time period. This helps meet any of the real-time constraints of the communication system.

FIG. 24 shows a method based on another implementation of the principles of the present application. In this example, the decoder monitors the frequency with which the indicator signal is received through the at least one communication channel (2402). These indicator signals indicate the quality of communication through the at least one communication channel. Based on the frequency of occurrence of such monitored indicator signals, the modulation scheme used to transmit data over the communication channel can be changed or changed for subsequent data transmissions (2404). .. This change or change leads to, for example, an instruction to increase the modulation order for a higher data rate, or a lower bit rate when the communication channel is determined to better support a lower modulation order. Can be an instruction to lower the modulation order, which increases the reliability of the data.

According to some exemplary implementations, the form of the indicator signal is an acknowledgment signal (eg ACK), a negative acknowledgment signal (NACK) or any other that its generation or receipt can be used to determine the quality of the communication channel. It can be any specified signal. Examples of the use of ACK and NACK are given above.

FIG. 25 shows an implementation of FIG. 24, which is a further modified method in which a time period is imposed on the monitoring of the frequency of occurrence of the received indicator signal. As shown in the figure, the frequency of occurrence of the received index signal is monitored (2504) for a predetermined time period (2502). Upon expiration 2504 of a given time period, the modulation scheme used to transmit subsequent data through at least one of the communication channels is modified to maximize the modulation scheme and raise the data rate to the maximum that the channel can support. Be (2506). However, as described above, change of the modulation scheme, the communication channel is higher support the modulation orders as it can sometimes not be bets can also be a request for reduction or lower order modulation. Implementations can vary as to how to determine if a channel can support higher order modulation. For example, one implementation declares that a channel can support a particular modulation format (order) is high (using a typical forward error correction code) so that all errors can be corrected in the data sent through that channel. Only if there is expectation.

FIG. 26 shows a method 2600 based on a further implementation of the principles of the present application. First, the frequency of occurrence of the received indicator signal is monitored (2602). In this regard, a modulation format determination is made that is expected to improve or potentially maximize "good" throughput (the amount of data received and decoded correctly per unit time) (2604). The determined format may be an optimal modulation format that can be supported by the at least one communication channel using the frequency of occurrence of the indicator signal data. For example, a LUT may be developed that correlates the ACK frequency (for a given modulation format) with the highest modulation format that can be supported. Subsequent changes in modulation scheme 2606 are performed using the determined modulation format supported by the channel.

FIG. 27 shows a method 2700 based on another implementation of the principles of the present application. In this implementation, the receiver of the transmitted data generates an indicator signal indicating the secure receipt and decoding of the data received through at least one of the communication channels and sends it to the transmitter (2702). The frequency of indicator signal generation is monitored (2704). Based on the frequency of occurrence of the monitored indicator signal, a modulation scheme indicator (2706) for subsequent transmission of data through said channel is given to the source of the received data.

FIG. 28 shows a modified method 2800 of the method shown in FIG. In this implementation, a predetermined time period is established (2805) to time the monitoring of the frequency of occurrence of the generated indicator signal (2804). Upon expiration of a predetermined time period, the receiver indicates a modulation scheme for subsequent data transmitted through said at least one communication channel (2806).

FIG. 29 shows another implementation 2900 of the principle-based method of the present application. As shown, the receiver generates an indicator signal and sends it to the source of the received data (2902), and the frequency of occurrence of the indicator signal is monitored (2904). As before, in this implementation, monitoring is performed for a given time period (2906). When the time period expires, the receiver sends a modulation index to the incoming data source to modify the modulation scheme used to transmit subsequent data through at least one of said communication channels (2908). ).

The modulation index can be any type of signal that the transmitter / encoder can recognize and act on. For example, the modulation index can be a control signal provided in the header of other data fed back from the receiver to the transmitter. In other implementations, it can also be part of an indicator signal (which can be ACK or NACK). Those skilled in the art will recognize that the shape of the modulation index may be any suitable shape.

FIG. 30 shows a decoder 3000 based on the principled implementation of the present application. The decoder 3000 includes a receiver 3002 configured to receive incoming data via the at least one communication channel 3012. The incoming data may be encoded with a non-rate code. Controller 3004 is configured to calculate quality metrics for communication channel 3012. The quality measure represents the capacity of the at least one communication channel. Once the quality metric has been calculated, the controller works with processor 3006 to have the decoder generate a modulation index using the calculated quality metric. As discussed above, the modulation index is a control that feeds back to the source of the transmitted data and gives the source instructions to modify the modulation scheme used to transmit subsequent data through communication channel 3012. It is a signal. The decoder 3000 also includes a memory / data unit 3008 and a clock 3010.

According to this implementation, quality metric is a concrete determination of the quality level that can be obtained on communication channel 3012. One example of such quality metric would be the signal-to-noise ratio (SNR) of channel 3012. The SNR of a channel can be used in conjunction with other known information such as current modulation schemes to identify new or modified modulation schemes to maximize channel usage. In a system with multiple communication channels to transmit modulated data, such as a layered communication system, the average SNR for all channels can be used as a quality measure. Alternatively, the average SNR for each channel can be used as a quality measure for each channel. The average can be an average across layers, a temporal average, and so on. In other alternative implementations, block-by-block SNRs may be used without departing from the spirit of the principles of the present application. Other implementations may include a peak SNR determination for use as a quality metric.

With reference to FIG. 31, an exemplary method 3100 implemented by the decoder 3000 based on some aspect of the principles of the present application is shown. First, the decoder accesses information related to the quality of communication through the at least one communication channel (3102). A determination is then made about the modulation format currently used to send the signal through the at least one communication channel (3104). Once the current modulation format has been determined, the decoder uses that information along with the quality information accessed and orders the source of the received data to modify the modulation format used to send subsequent data. Including indicators can be given (3106).

According to another implementation shown in FIG. 32, Method 3200 accesses information related to communication quality (3202) to determine the current modulation format used on at least one of the communication channels. (3204) Provide that. Quality metric (eg, frequency of SNR or ACK) is then calculated from the accessed information related to the quality of the communication channel (3206). The calculated quality metric is then used to indicate the modulation scheme that should be used to send subsequent data through the channel in the context of known or current modulation formats (3208).

FIG. 33 shows another implementation 3300 of the method based on the principles of the present application. In this implementation, the decoder receives data encoded with no rate code (3302). Using this data, the decoder calculates the quality measure (3304). This quality metric provides information related to the optimal modulation format supported by the at least one communication channel.

Using the calculated quality metric, the decoder orders the source of the received data to modify the modulation scheme used to transmit subsequent data through said at least one communication channel (3306).

FIG. 34 shows a modified method implementation 3400 of the method shown in FIG. As before, the decoder receives the unrate-coded encoded data (3402) and calculates a quality metric that indicates the optimal modulation format supported by at least one communication channel (3404). The decoder then responds to the calculated quality metric to generate a modulated index signal indicating the modulation scheme to be used by the source of the data received to send subsequent data through said at least one communication channel.

Obviously, many implementations described in this application can be performed by receivers, transmitters, or both.

Various aspects, implementations and features may be implemented in one or more of the various ways, even though they are described above without reference to a particular way, or only in one way. For example, various aspects, implementations and features are among devices and computer-readable media, including, for example, methods, devices, devices or processing devices for performing methods, programs or sets of other instructions, programs or sets of instructions. It can be implemented using one or more.

The device may include, for example, discrete or integrated hardware, firmware and software. As an example, the device may include, for example, a processor. This processor refers to processing devices in general and includes, for example, microprocessors, integrated circuits or programmable logic devices. As another example, the device may include one or more computer-readable media having instructions to perform one or more processes.

Computer-readable media may include software carriers or other storage devices such as, for example, hard disks, compact diskettes, random access memory (RAM) or read-only memory (ROM). Computer-readable media can also include, for example, formatted electromagnetic waves that encode or transmit instructions. The instructions may be, for example, hardware, firmware, software or electromagnetic waves. Instructions may be found, for example, in the operating system, separate applications, or a combination of both. Thus, a processor can be characterized, for example, as either a device configured to run a process or a device containing a computer-readable medium with instructions to run the process.

A number of implementations have been described, but it will be understood that various modifications can be made. For example, the elements of various implementations may be combined, supplemented, modified, or removed to produce other implementations. Therefore, other implementations are also within the scope of the claims.