Abstract:
Skipping, spreading or otherwise metering signaling across multiple transmission opportunities is contemplated. The contemplated signal processing may be beneficial in ameliorating the influence of burst noise and other interferences on signal transmissions. The contemplated signal processing may be operable to facilitate supplementing and/or replacing other error correction techniques aimed at reducing signaling interference.

Description:
TECHNICAL FIELD 
     The present invention relates to ameliorating the influence of burst noise and other interferences on signal transmissions, such as by skipping or spreading signaling across multiple transmission opportunities. 
     BACKGROUND 
     U.S. patent application Ser. No. 13/538,456, entitled Interleaved Signaling, and U.S. patent application Ser. No. 13/841,313, entitled Orthogonal Signal Demodulation, the disclosures of which are hereby incorporated by reference in their entireties, relate to the transmission, modulation and demodulation of data through the use of various signaling techniques. The signaling described in the incorporated patent applications, as well as other types of wired and wireless signaling, may be susceptible to impairments added to the transmitted signal as it traverses a signal path. Particularly problematic impairments may result from random noise and/or burst noise. Random noise may be continuous in the time domain and generally flat or “white” in the frequency domain. Burst noise may be strong in amplitude, but relatively short in duration, which may include the noise being wide in frequency. Burst noise may be caused by switching in electrical circuits, such as switching regulated power supplies, switching inductive loads with mechanical contacts, automotive ignitions, and power supplies for lighting such as compact florescent lamps, etc. 
     Forward error correction (FEC), Reed-Solomon (RS) codes, low-density parity-check codes (LDPC) and error other block FEC techniques, such as but not necessarily limited to those described in the incorporated patent applications, may be used to ameliorate channel errors resulting noise related impairments. One non-limiting aspect of the present invention contemplates supplementing and/or replacing such error correction techniques in order to facilitate ameliorating noise influences on transmitted signaling. 
     Block codes have overhead, in the form of additional data added to allow FEC. Generally a stronger error correction ability requires more overhead. When a noise burst is received, an efficient block code with low overhead, which was designed to correct random symbol errors associated with Gaussian (random) noise, will be unable to correct all of the errors caused by the burst. This results in an uncorrectable block. A solution that has been implemented is interleaving, where the noise burst is spread over multiple code blocks, and each code block receives a lesser number of symbol errors, resulting in a corrected code block. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a system for transporting signals in accordance with one non-limiting aspect of the present invention. 
         FIG. 2  illustrates a MAP in accordance with one non-limiting aspect of the present invention. 
         FIG. 3  illustrates one of the minislots in accordance with one non-limiting aspect of the present invention. 
         FIG. 4  illustrates a diagram of a method for transmitting data in accordance with one non-limiting aspect of the present invention. 
         FIG. 5  illustrates a diagram of a method for transmitting data in accordance with one non-limiting aspect of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
       FIG. 1  illustrates a system  10  for transporting signals in accordance with one non-limiting aspect of the present invention. The system  10  is shown with respect to a transmitter  12  being configured to transport signaling over a network  14  for receipt at a receiver  16 . The receiver  16  may be configured to further process the transported signaling for output to a device (not shown) and/or interfacing with a user. The system  10  may be configured to facilitate transporting virtually any type of signaling between a first location/device (e.g., the transmitter  12 ) and a second location/device (e.g., the receiver  16 ). Optionally, the signaling transported over or through the network  14  may traverse one or multiple wired and/or wireless mediums before reaching the receiver  16 , such as in the manner described in the patent applications referenced above and/or described in U.S. patent application Ser. No. 14/181,640, filed Feb. 15, 2014, and entitled Multiple-Input Multiple-Output (MIMO) Communication System, the disclosure of which is hereby incorporated by reference in its entirety. The relationship of the transmitter  12  and the receiver  16  is shown for exemplary non-limiting purposes as the present invention fully contemplates the transmitter  12  acting as a receiver or a client in some circumstances and the receiver  16  acting as a transmitter or a server in some circumstance. 
     The present invention is predominantly described with respect to facilitating signaling over any the network  14  or other sufficient medium between the transmitter  12  and the receiver  16 . The network  14  be a public or private network having capabilities sufficient to facilitate processing of signals transmitted according to but not limited to Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiplexing (OFDM), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), code division multiple access (CDMA) and any other modulation technique that allow granular allocation of signals in a time and/or a frequency domain and/or code domain. The network may be configured to facilitate processing signals communicated according to any number of standards and/or protocols, such as but not necessary limited to Data Over Cable Service Interface Specifications (DOCSIS) 3.1, Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wi-Max, Wi-Fi, Digital Video Broadcasting-Terrestrial (DVB-T), Digital Video Broadcasting-Handheld (DVB-H), etc., the disclosures of which are hereby incorporated by reference in their entireties. One non-limiting aspect of the present invention contemplates a scheduler being operable with one or more of the transmitter  12 , the network  14  and/or the receiver  16  to facilitate scheduling and/or processing of signals communicated therebetween, regardless of whether signaling is transmitted according to one of the above-identified protocol/standards or another. 
     The scheduler  20  is shown for exemplary non-limiting purposes as being a standalone item but may be incorporated or otherwise associated with one or more suitable components within the system  10 . The scheduler  20  may be configured in accordance in the present invention to facilitate scheduling data for transmission from the transmitter  12  to the receiver  16  via the network  14 . One non-limiting aspect of the present invention contemplates the scheduler  20  being configured to facilitate transporting data according to DOCSIS 3.x, which as described in Data-Over-Cable Service Interface Specifications DOCSIS 3.1: Physical Layer Specification CM-SP-PHYv3.1401-131029, the disclosure of what is hereby Incorporated by reference in its entirety. As noted in DOCSIS 3.1, a cable modem (CM), a cable modem termination system (CMTS) or other suitable transmitter and/or receiver  12 ,  16  may utilize a convergence logical layer between MAC (media access control) and PHY (physical) layers to facilitate OFDM downstream channels and OFDMA upstream channels, such as to map data for transmission. The scheduler  20  may be configured to facilitate mapping or otherwise scheduling data for transmission according to a transmission schedule, e.g., the scheduler  20  may provide instructions to the transmitter  12  sufficient to facilitate partitioning MAC frames into codewords and to map codewords into minislots relative to a transmission schedule utilized by the transmitter to transmit related signaling over the network  14 . 
       FIG. 2  illustrates a MAP  30  in accordance with one non-limiting aspect of the present invention. The MAP  30  may be used to represent network resources or space that is available to facilitate network-based data transmission, such as in the manner described in U.S. patent application Ser. No. 12/827,496, entitled Systems And Method Of Decoupling Media Access Control (MAC) And Physical (PHY) Operating Layers, the disclosure of which is hereby Incorporated by reference in its entirety. The MAP illustrates a number of channels  32 ,  34 ,  36 , each associated with a portion of a plurality of minislots ( 1 - 3300 ). Each minislot corresponds with one sub-channel and one sub-frame, the sub-channels corresponding with a frequency (F 1 -F 15 ) and the sub-frames corresponding with a unit time ( 1 - 10 ).  FIG. 3  illustrates one of the minislots in accordance with one non-limiting aspect of the present invention. Each minislot may be used to represent a capacity unit comprised of a number of sub-carriers over time. The sub-carriers may be grouped based on their capacity characteristics to form a sub-channel of constant capacity. One non-limiting aspect of the present invention contemplates collecting or otherwise arranging the sub-carriers such that each minislot totals the same capacity, regardless of the actual number of sub-carriers being used to form each minislot. (As one skilled in the art will appreciate, the amount of data that can be carried by certain sub-carriers can vary according to frequency, network characteristics, etc.). 
     The frequency (sub-channel) and time (sub-frame) coordinates represented along the vertical axis and the horizontal axis respectively may be used identify a starting frequency (start sub-channel) and an encompassed frequency range (number of sub-channels) as well as a start time (start sub-frame) and a duration (number of sub-frames) of data transmitted over the network. The scheduler  20  may be responsible for supporting the MAP  30  and coordinating scheduling and allocation of the related resources in order to enable the data communications required by the end stations  16  and the services provided therethrough. In order for the data to be transmitted over the network  14 , it may be mapped to the two-dimensional MAP  30  (transmission schedule), or a similar two-dimensional MAP, in the event the data is being transmitted over the type of network that allocates resources in two-dimensions as function of frequency and time. The two-dimensional mapping contemplated by the present invention requires detailed knowledge about available sub-carriers and related processing in order to properly group the sub-carriers into the same sized (capacity) sub-channels, including capabilities to monitor available network resources and continuously changing characteristics of the sub-carriers (as one skilled in the art will appreciate, the amount of data each sub-carrier can transport may vary over time according to any number of steady or transient network conditions, such as but not limited to sub-carrier RF level distortion, background noise level, and the presence of burst noise). 
     The two-dimensional mapping may also require knowledge of the two-dimensional MAP parameters such as the MAP duration in sub-frames and the number of sub-channels to be used for transmission. These parameters may be configurable to achieve the intended performance (latency, robustness). In order the limit the complexity of the MAC layer and/or to allow scaling of the MAC layer to support high speed operations, one non-limiting aspect of the present invention contemplates shielding the MAC layer from having to append data necessary to map the data input, i.e., the logic link control (LLC) frame, to the two-dimensional MAP. The scheduler  20  may be configured to facilitate mapping the codewords to the transmission schedules such that each codeword is scheduled for transmission during one or more of the minislots. The minislots may be defined in the above-described manner relative to a frequency domain and a time domain such that the scheduler  20  may be responsible for scheduling transmission of the codewords relative to the frequency and/or time domains. The foregoing is provided for exemplary non-limiting purposes as one example of a two-dimensional transmission schedule as the present invention fully contemplates its use and application with other types of transmission schedules, including schedules that may be limited in the frequency domain or require signaling to be transmitted at a fixed frequency such that the schedule may only be responsible for scheduling transmission according to the time domain. 
       FIG. 4  illustrates a diagram  40  of a method for transmitting data in accordance with one non-limiting aspect of the present invention. The method may be controlled with the scheduler  20  or other device having a non-transitory computer-readable medium with a plurality of instructions operable to facilitate directing, controlling or otherwise implementing the operations contemplated herein. The method is predominantly described for exemplary non-limiting purposes with respect to facilitating data transmissions from the transmitter  12  to the receiver  16 . This is done without intending to limit the scope contemplation of the present invention as the operations and processes contemplated herein may be sufficient to facilitate scheduling other types of transmissions besides those associated with the transmitter  12  and the receiver  16 . Block  42  relates to identifying data desired for transmission, such as a MAC frame or other identifiable data construct. Block  44  relates to facilitating partitioning of the data into a plurality of codewords, such as in the manner described in DOCSIS 3.1. The partitioning may be characterized by dividing the data desired for transport into a plurality of smaller datasets referred to as codewords due to each of the codewords being assigned parity, forward error correction (FEC), a header and/or or other types of bits/bytes sufficient to distinguish each from one another. The parity data may be added to each codeword to facilitate enabling the receiver  16  to recover missing information or otherwise provide error correction, such as to enable data recovery when signal transmissions are disrupted or otherwise experience interference. 
     Block  46  relates to adding the parity (FEC etc.) to the data while being partitioned into each codeword. Following the partitioning, each codeword may comprise a header portion, a payload portion and a parity portion. (Optionally, the header portion may be eliminated or unnecessary in some implementations of the present invention, such as when if a CMTS is expecting the transmission and/or the CMTS told the transmitter when and at what frequency to transmit). If generated in accordance with DOCSIS 3.1 a full codeword may be comprised of 2025 bytes (16200 bits) divided into 225 bytes (1800 bits) of parity and 1800 bytes (14400 bits) of low-density parity check (LDPC) payload. That payload may be further divided into 21 bytes (168 bits) of Bose, Ray-Chaudhuri, Hocquenghem (BCH) parity, a 2 byte fixed header, and a variable 1777 byte maximum payload for DOCSIS frames. The partitioning of the data into the codewords may be characterized by each codeword comprising a certain number of bits allocated to each of the header, payload and parity portion. While the partitioning is predominantly described with respect to generating codewords, other data construct having a similar function or partitioning may be utilized without deviating from the scope contemplation of the present invention, e.g., some protocols or standards may use any linear block code as an equivalent to the described codeword. The scheduler  20  may be configured in accordance with the present invention to facilitate scheduling transmission of the codewords in a manner aimed at ameliorating the influences of burst noise or other signal disruptions. 
     The scheduler  20  may schedule transmission of the codewords to ameliorate the influences of burst noise or other signal disruptions by segmenting one or more of the codewords desired for transmission into a plurality of segments. The segments may each comprise a portion of the total number of bits corresponding with the associated codeword such that all segments in total equals or exceeds the same number of bits as in the corresponding codeword. Optionally, data may be added to each codeword to facilitate re-constructing and/or other operations at the receiver once all segments are received.  FIG. 4  illustrates a scenario where the scheduler  20  schedules transmission of a first codeword  46  and a second codeword  48  such that the first codeword  46  is segmented into a first, second, third, fourth and fifth segment (seg  1 , seg  2 , . . . seg n) and the second codeword  48  is not segmented. The segmentation of the first codeword  46  may be characterized by each of the corresponding segments being spaced apart in the time domain, which for exemplary non-limiting purposes is shown to correspond with a time interval (T) defining the equal spacing of each segment. The scheduler  20  may selectively determine the time interval (T) according to any number of variables and parameters and may adjust the interval between each segment to facilitate desired signal transports, i.e., each of the segments need not necessarily be equally spaced from each other in the time domain. The second codeword  48  illustrates a total number of bits comprising the second codeword  48  being scheduled for successive transmission such that each bit occurring from a beginning bit to and an ending bit is transmitted in adjoining sequence, i.e., without any gaps or separation within the time domain. Segmentation may be done, for example, in response to the detection of burst noise on the (upstream) channel. Those skilled in the art will recognize that segmentation causes increased latency, but a small increase in latency may be much preferable to the data stopping. Furthermore, the time intervals (T) represent signaling (transmission) opportunities for other users. The timing of the time intervals (T) may be set to align with noise peaks associated with the 60 or 50 Hz power line frequencies. Switching regulator noise has been observed to increase and decrease at a 120 Hz rate with 60 Hz AC power because of switching of rectifier diodes in switching power supplies. 
     The scheduler  20  may be configured to facilitate scheduling the transmission of the first and second codewords  46 ,  48  by assigning the segments to individual minislots such that at least one minislot separates each segment of the first codeword  46  and such that no minislots separate the beginning and the ending bits of the second codeword  48 . Of course, the present invention is not necessarily so limited and fully contemplates the scheduler  20  being configured to facilitate scheduling transmission according to other units of time besides minislots. The scheduler  20  may also be configured to facilitate segmenting the second codeword  48  or any additional number of codewords partitioned from the data in a manner similar to that described with respect to the first codeword  46 , optionally with each segment of a corresponding codeword having the same skipped time interval (T) or other time interval uniquely determined for its transmission. The scheduler  20  may be configured to facilitate scheduling the second codeword  48  or any additional codeword being segmented such that one or more of the segments associated therewith are scheduled to occur within the interval T occurring between one or more of the segments associated with the first codeword  46  or another codeword, e.g., a first segment (seg  1 ) and a second segment (seg  2 ) of the first codeword  46  may be scheduled and then a first segment of a second codeword (not shown) may be scheduled to occur therebetween such that at least one segment of the first codeword  46  adjoins a segment of the second codeword. 
     One non-limiting aspect of the present invention contemplates the scheduler  20  or other device having an algorithm or other logic sufficient to facilitate determining segmentation of the codewords and a skipping interval (e.g., time interval T). A first segment value (S) representative of the number of segments associated with the first codeword or other segmented codewords may be determined according to the following: S=x.ceil(m/k), wherein x=a segmentation factor ≧1; m=length of the first codeword in bits; and k=maximum correctable number of bits. The segmentation factor may be selected to be one in order to determine a minimum number of segments and selected to be a higher value is more segments are desired. The number of segments influences the duration or time taken to transmit a particular codeword and the likelihood that the codeword is affected by a noise burst, e.g., a greater number of segmentations takes longer to transmit but is less likely to be affected by a noise burst in comparison to a lesser number of segmentations. The m and k values may be design parameters associated with typical codeword sizes and/or other values characteristics of network transmissions and may be set to other variables such as symbols, etc. 
     The skipping interval or time interval (T) may be determined according to the following: T=ceil[((P*B)/(k/Rb*S))−1], wherein B=a duration of a burst noise; P=percentage of the burst noise anticipated to affect transmission of the data; Rb=a transmission rate of the first codeword; and S=the segmentation value determined above. The duration of the burst noise B may be measured or estimated to reflect a known burst noise and/or an anticipated burst noise. The percentage P of the burst noise anticipated to affect the transmission may be determined to be 80% or some other value sufficient to indicate how much of the burst noise will actually affects signal transmissions, e.g., the burst noise may experience a rise at a beginning and a drop at an end such that only the portion occurring therebetween may be relevant for calculation purposes. Optionally, such as to ensure success of the forward error correction or other parity-based processes, the percentage P may be selected to be less than or equal to k/m. The transmission rate Rb may be determined by the communication medium, network or other transmission capabilities associated with facilitate signaling between the transmitter and the receiver and may vary over time according to congestion or other network variables. In this manner, the skipping interval may be determined in the time domain to facilitate spacing each segment associated with a comment codeword. The time unit associated with the skipping interval T may vary according to the transmission schedule or other intervals at which the transmitter  12  may be able to time signal transmissions, e.g., the interval T may be a value where the units are relative to the transmission schedule or capabilities of the transmitter  12 . 
     Once the segmentation interval (S) and the skipping interval (T) are determined, the scheduler  12  may be configured to facilitate providing suitable instructions to the transmitter  12  and/or the receiver  16 . The instructions may be sufficient for enabling the transmitter  12  to schedule a transmission of the corresponding segments and/or codewords according to the appropriate transmission schedule (e.g., a transmission schedule similar to that shown in  FIG. 2  where segments may be scheduled in the time and/or frequency domains). The scheduler  20  may provide instructions to the receiver  16  having spacing information sufficient to facilitate buffering the segments associated with each codeword. The receiver  16  may utilize the spacing information to identify time periods when to clock into a buffer in order to facilitate buffering the segments, e.g., when expecting to receive when the segments, the receiver  16  May clock into the transmitted signaling and thereafter clock out in order to reduce the amount of data being buffered for processing. Of course, the instructions provided to the receiver  16  may vary depending on the capabilities of the receiver and its ability to selectively buffer and/or to selectively store data or other signaling transmitted thereto. 
       FIG. 5  illustrates a diagram of a method for transmitting data in accordance with one non-limiting aspect of the present invention. The scheduling associated with  FIG. 5  is shown to be variable relative to both of a time domain and a frequency domain whereas the scheduling associated with  FIG. 4  is shown to be variable relative to the time domain. The scheduler may be configured to facilitate scheduling according to the frequency and time domains in the manner similar to that described above with respect to  FIG. 4 , e.g., identifying a number of segments and then identifying an offset or skipping to be performed between each segment. The additional frequency domain scheduling may include scheduling segments such that segments skipping occurs relative to a time interval T as well as a frequency interval F. The frequency interval F may be selected for similar purposes as that described above with respect to the selection of the time interval T, e.g., to facilitate transmitting codewords across different frequencies in order to ameliorate the likelihood of interferences affecting an entirety of the corresponding codeword. As with the time interval T, the frequency interval F is shown to correspond with equal frequency spacing between each of the segments for exemplary non-limiting purposes as the frequency interval F may be selected to vary between segments and/or as a function of individual codewords. This embodiment would have a relative advantage against an intermittent narrowband interferer, such as Ham radio traffic. 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.