Spectrum analysis capability in network and/or system communication devices

Spectrum analysis (SA) capability is included in various communication devices within a communication network. One or more of the devices use the SA information from other devices in the system to determine status of various communication links were devices in the system. One or more processors within one or more devices can identify any actual/existing or expected failure or degradation of the various components within the system. Such components may include communication devices, communication channels or links, interfaces, interconnections, etc. When an actual/existing or expected failure or degradation is identified, the affected components may be serviced or devices within the system may operate to mitigate any reduction in performance caused by such problems. Such SA functionality/capability may be implemented in one communication device or in a distributed manner across a number of devices in a communication system.

BACKGROUND

1. Technical Field

The present disclosure relates generally to communication systems; and, more particularly, to characterizing, tracking, and/or monitoring operation of various components and/or elements within such communication systems

2. Description of Related Art

Data communication systems have been under continual development for many years. Sometimes, problems may occur that affect one or more of the various components within such communication systems so that the overall performance is less than optimal. Various problems such as equipment failure, degrading interfaces or connectors, etc. reduce the overall effectiveness of communications within such communication systems.

Diagnosis of such problems is typically performed by service personnel who conduct a service call to one or more locations where customers complain of poor service. Also, such service personnel can only analyze one given location at a time. A great deal of time is required to perform analysis of multiple locations within a communication system, and this procedure may be very labor and cost intensive.

Even after existing problems are identified and repaired, other problems may subsequently arise and cause other problems which also lead to degradation of the communication system's performance. Generally, a communication system's overall performance and fitness is dynamic and changing over time.

DETAILED DESCRIPTION

FIG. 1is a diagram illustrating an embodiment100of one or more communication systems. One or more network segments190provide communication inter-connectivity for at least two communication devices110and120. Generally speaking, any desired number of communication devices are included within one or more communication systems (e.g., as shown by communication devices one130and140). Some or all the various communication devices110-140include capability to generate spectrum analysis (SA) information based on the one or more communication channels via which they communicate to other devices. For example, SA information may include various characteristics such as a communication channels frequency response, a device's internal frequency response (e.g., how that devices operation may affect the various communication channels via which it communicates), interference or noise detected on communication channel, reflections, frequency nulls on a communication channel, etc. Also, such SA information may correspond to changes or trends associated with any such characteristics. The various devices110-140provide SA information to other of the devices110-140for use in determining the operation of the one or more communication systems. SA information may be provided automatically between various devices110-140, such as at particular times (e.g., periodically, or aperiodically such as when a device is idle or has processing capability to generate such SA information, such as when not using all of the device's processing resources or capabilities). Alternatively, such SA information may be provided upon one device requesting it from another. Generally, a device (e.g., cable modem termination system (CMTS)) can receive various SA information from different devices in the one or more communication systems. At least some of this SA information is based on full bandwidth of a usable frequency spectrum in the one or more communication systems. For example, in the context of a cable based system, at least some SA information is wideband to allow observation of the whole cable plant signal from 54 MHz to 1008 MHz and beyond these limits. Based on the received SA information, this device then has a great deal of visibility into the one or more communication systems. From the perspective of a device such as a CMTS in a cable based system, the CMTS has a broad range of visibility into the entirety of the downstream radio frequency (RF) including any or all of the various service flows included in such a cable plant system such as those described with reference toFIG. 2.

For an example of operation, device110includes a communication interface to transmit a signal to device122request SA information there from. The device110includes a processor to process the received SA information and to determine one or more other characteristics (e.g., which can be used to identify an operational error, failure, or degradation, an operational trend, a future or expected operational error, failure, or degradation, etc.) associated with performance of one or more communication channels in the system. Based on the one or more other characteristics, the device110may then identify an actual/existing and/or expected failure or degradation of communication associated with those one or more communication channels.

In another example of operation, device110may receive first SA information from device120and second SA information from device130. Device110can then employ both the first SA information and the second SA information to determine an operational trend of one or more communication channels in the system. This first SA information and second SA information may correspond to two entirely different components within the system, or it may correspond to a common components (e.g., such that the first and second SA information corresponds to two different times).

In an example of SA information generation, device120may receive a signal that includes pilot tones from device110. Device120can then process the received pilot tones, and compared to their expected values, can determine the effect of the communication link between devices110and120. That is to say, device120generates SA information based on characterization of the pilot tones received from device110. Device120can then provide this SA information may then be provided to device110automatically or upon request. In addition, device120may use this recently generated SA information to characterize operation of the communication link between devices110and120including identifying an actual/existing or expected failure or degradation of communication via that communication link.

In another example of SA information generation, device120may include an equalizer that employs equalizer coefficients to perform equalization of signals that it receives. Device120may provide SA information to device110that is based on the values of those equalizer coefficients or changes in those equalizer coefficients relative to prior values.

Also, any of the various devices110-140may have an internal frequency response that affects operation of the system, and SA information may be based on a given device's internal frequency response. For example, device120may provide essay information to device110that is based on the frequency response of the device120in terms of its effect on the system.

Various examples have been described in which a given device, such as device110, performs the appropriate processing to determine an operational trend of one or more components in the system and also to identify an actual/existing or expected failure or degradation of communication associated with those one or more components. Note also that such processing may be implemented in a distributed manner among two or more of the devices110-140. That is to say, two or more of the devices110-140may operate cooperatively to process SA information and to determine any such actual/existing or expected failure or degradation of communication associated with those one or more components. The various devices110-140may communicate signals amongst one another related to such actual/existing or expected failure or degradation of communication associated with those one or more components. Generally speaking, such SA functionality/capability may be implemented in a distributed manner across a number of devices within one or more communication systems. Also, when an actual/existing or expected failure or degradation is identified, the affected components may be serviced (e.g., by service personnel) or devices within the system may operate adaptively to mitigate any reduction in performance caused by such problems.

With respect to a particular type of SA functionality included within a remote device (e.g., within any of the various devices110-140), the remote SA functionality may be wideband (e.g., observing the entire usable frequency spectrum associated with the communication system). For example, considering a cable plant type implementation, remotely implemented SA functionality may be wideband to allow observation of the whole cable plant signal from 54 MHz to 1008 MHz and beyond these limits. This permits the headend (or CMTS) to view problems that are affecting channels other than the ones currently in use by a given home/premises. For example, a micro-reflection in the cable may produce a ripple in the frequency response with a relative null on a given frequency channel “A”. The user may at the current time be using channel “B” which is not affected by the null, so his service has not yet been compromised by the presence of this reflection. However, in the future the null could move in frequency close to channel A (due to phase changes in the physical process producing the reflection/null), or the service currently on channel B could be moved to channel A, either of which would cause the null to begin to affect the service at this customer. With the wideband SA the headend (or CMTS) will observe the null on channel A, and will be able to perform preventive maintenance to fix the reflection/null before the problem occurs.

FIG. 2is a diagram illustrating another embodiment200of one or more communication systems. A cable headend transmitter230provides service to a set-top box (STB)220via cable network segment298. The STB220provides output to a display capable device210. The cable headend transmitter230can support any of a number of service flows such as audio, video, local access channels, as well as any other service of cable systems. For example, the cable headend transmitter230can provide media (e.g., video and/or audio) to the display capable device.

The cable headend transmitter230may provide operation of a cable modem termination system (CMTS)240a. That is to say, the cable headend transmitter230may perform such CMTS functionality, or a CMTS may be implemented separately from the cable headend transmitter230(e.g., as shown by reference numeral240). The CMTS240can provide network service (e.g., Internet, other network access, etc.) to any number of cable modems (shown as CM1, CM2, and up to CM n) via a cable modem (CM) network segment299. The cable network segment298and the CM network segment299may be part of a common network or common networks. The cable modem network segment299couples the cable modems1-nto the CMTS (shown as240or240a). Such a cable system (e.g., cable network segment298and/or CM network segment299) may generally be referred to as a cable plant and may be implemented, at least in part, as a hybrid fiber-coaxial (HFC) network (e.g., including various wired and/or optical fiber communication segments, light sources, light or photo detection complements, etc.).

A CMTS240or240ais a component that exchanges digital signals with cable modems1-non the cable modem network segment299. Each of the cable modems coupled to the cable modem network segment299, and a number of elements may be included within the cable modem network segment299. For example, routers, splitters, couplers, relays, and amplifiers may be contained within the cable modem network segment299. Generally speaking, downstream information may be viewed is that which flows from the CMTS240to the connected cable modems (e.g., CM1, CM2, etc.), and upstream information is that which flows from the cable modems to the CMTS240.

At least some of the devices within this diagram support the SA information functionality described herein. For one example of operation, the CMTS240may be implemented to include a communication interface to transmit a signal to CM1to request SA information there from. The CMTS240includes a processor to process the received SA information and to determine an operational trend of one or more communication channels in the system (e.g., between the CMTS240in the CM1). Based on the operational trend, the CMTS240may then identify an actual/existing or expected failure or degradation of communication associated with those one or more communication channels. Analogously, any of the other devices within the diagram may also include such SA capability as described herein. The various devices within the diagram may communicate SA information to each other and also provide information based on operational trends and actual/existing or expected failures or degradations of communications made along the various communication paths between the various devices in the diagram. In one example of operation, any one or more of the cable modems or and/or the STB220can include capability to generate SA information based on one or more communication channels within the communication system. Some or all of the SA information can be based on full bandwidth of a usable frequency spectrum in the communication system. This SA information can be provided to another device (e.g., the CMTS240) for use in determining one or more characteristics associated with performance of the one or more communication channels in the communication system and for identifying, based on the one or more characteristics, a degradation of communication associated with the one or more communication channels.

FIG. 3is a diagram illustrating a communication device110operative within one or more communication systems. The device110includes a communication interface320and a processor330. The communication interface320includes functionality of a transmitter322and the receiver324to support communications with one or more other devices within a communication system. The device110may also include memory340to store information including SA information generated by the device110or SA information received from other devices via one or more communication channels. Memory340may also include and store various operational instructions for use by the processor330in regards to the SA functionality described herein.

The device110operates to transmit and receive SA information and/or requests for such SA information to and from other devices within the communication system. For example, the communication interface320may be configured to transmit requests to one or more other devices within the system to request SA information. Those other devices will then transmit SA information to the device110, and the processor330will process the SA information to determine one or more operational trends associated with one or more communication channels within the system. Based upon the identified operational trends, the processor330will then identify any actual/existing or expected failures or degradations of communications associated with the communication system.

FIG. 4is a diagram illustrating an embodiment400of one or more communication systems with multi-channel communication links. Communication devices110and120may communicate with one another via one or more communication channels (e.g., as shown by CH1through CH x). Each of the devices110and120include SA functionality. For example, device110includes a processor330in the memory340. Device120includes a processor330amemory340a. The memories340and340acan store SA information and/or include operational instructions for use by the processors330and330a.

Multiple network segments may interconnect the devices110and122other respective devices that may also include SA functionality therein. Any of the various devices may communicate with one another via the multi-channel communication links and/or network segments. SA functionality is distributed across multiple devices within the one or more communication systems. SA information is determined by these various devices and communicated to other of the devices for use in determining operational trends and/or actual/existing or expected failures or degradations of communications along any of the various communication links within the system.

FIG. 5is a diagram illustrating another embodiment500of one or more communication systems with multi-channel communication links. The embodiment500has some similarities to the previous embodiment400, in that, two respective devices may communicate with one another via multi-channel communication links. However, in this diagram, communication device510includes SA functionality1and communication device520includes SA functionality2. Different respective devices need not necessarily have the same SA functionality or capabilities. For example, device510includes components1,2, and up to y. Device520includes components1,2, and up to x. The devices510and520may include some common components, but need not necessarily include the same components. These different components can generate different types of SA information. For example, component1in device510may determine a channel estimate of a communication link. Component2in device510may determine a frequency response of that communication link. A component3(not shown) in device510may determine interference or noise detected on that communication link. Generally speaking, different components can have different respective capabilities and functions, and the devices510and530deed not necessarily have the exact same capabilities in terms of generating SA information. In addition, other respective devices330may also include different respective SA functionalities3as well.

Different devices implemented within the system that include different SA functionalities can operate cooperatively to provide a great deal of information regarding the overall operation of the communication system in which the devices reside. Also, an implementation that allows for different SA functionalities to be provisioned within different devices can provide for a more efficient implementation of resources.

FIG. 6Ais a diagram illustrating an example601of processing to identify an actual/existing or expected failure or degradation within a communication system. SA information in the form of frequency responses (e.g., frequency response1, frequency response2, and possibly up to frequency response n) undergo processing to determine an operational trend of at least one component within the system. This operational trend assists in the identification of an actual/existing or expected failure or degradation of that at least one component in the system.

FIG. 6Bis a diagram illustrating a communication channel602partitioned into multiple sub-bands or sub-channels. Some SA information may be wideband in nature such as spanning two or more of the sub-bands or sub-channels. In one or more embodiments, SA information may correspond to full bandwidth of communication system's usable frequency spectrum. Alternatively, other SA information may correspond to one of the sub-bands or sub-channels. Also, when various SA information corresponds to one of the sub-bands or sub-channels, the SA information may be combined to generate SA information that corresponds to full bandwidth of communication system's usable frequency spectrum.

The SA information can be generated using a combination of fast Fourier transform (FFT) and swept/stepped techniques. Considering one example of operation, samples from the wideband analog-to-digital converter (ADC) can be captured in a memory, an FFT/DFT (fast Fourier transform, discrete Fourier transform, or other filter bank technique) taken, and the entire broadband SA spectrum computed instantaneously based on those samples (e.g., corresponding to full bandwidth of communication system's usable frequency spectrum). Considering another example of operation, a single analog or digital filter can be swept or stepped across the band at each frequency that the received power is measured to provide a swept/stepped SA capability. Intermediate between these two examples of operation is stepping an FFT across the band to generate the SA information.

For example, a filter of 7.5 MHz bandwidth is positioned at a given frequency, samples are captured, and an FFT is taken. Then, the filter is moved to the next frequency, and the FFT is repeated. This process is repeated across the whole band from a first to a second frequency (e.g., from 54 MHz to 1008 MHz or wider). The individual narrowband (7.5 MHz) FFT segments are then combined or stitched together to produce wideband SA information.

Signaling on a given communication channel may be based on the given frequency or a given frequency band. Acquired or generated SA information may be relatively wideband such that it spans more than the frequency or frequency band associated with the communication channel. Alternatively, acquired or generated SA information may be relatively narrowband such that each individual SA information components may be but based on a sub-band of a relatively larger frequency band.

With respect to the particular SA functionality or capability included within a device, the SA functionality may be wideband (e.g., observing the entire usable frequency spectrum associated with the communication system) or narrowband (e.g., observing only narrowband portions of the frequency spectrum) such as with reference to the differing capabilities described inFIG. 5.

For example, considering a cable plant type implementation such as with reference toFIG. 2, remotely implemented SA functionality may be wideband (e.g., corresponding to full bandwidth of communication system's usable frequency spectrum) to allow observation of the whole cable plant signal from 54 MHz to 1008 MHz and beyond these limits. This permits a cable headend transmitter (or CMTS) to view problems that are affecting channels other than the ones currently in use by a given home/premises. For example, a micro-reflection in the cable may produce a ripple in the frequency response with a relative null on a given frequency channel “A”. At the current time, a CM may be using channel “B” which is not affected by the null, so that's CM's service has not yet been compromised by the presence of this reflection. However, in the future, the null could move in frequency close to channel A (due to phase changes in the physical process producing the reflection/null), or the service currently on channel B could be moved to channel A, either of which would cause the null to begin to affect the service at this customer. With the wideband SA functionality, the headend (or CMTS) may observe the null on channel A, and the headend (or CMTS) will then be able to perform preventive maintenance to fix the reflection/null before the problem occurs or fully manifests itself. One or more operational trends of one or more elements within a communication system (e.g., any device, communication channel or link, etc. within the communication system) may be determined, monitored, tracked, etc. to ascertain historical and current operation of any such elements and also to estimate or predict future operation of any such elements.

Also, to improve SA selectivity, window functions such as Hanning, Hamming, Blackman/Harris, etc. may be applied to the FFT results in the time and/or frequency domains. Windowing permits the SA to display signals of large power difference (large dynamic range) which are close together in frequency, without blurring them together, and it also permits accurate measurement of signal power. Also, such techniques may also be extended in various works on multi-rate signal processing.

The SA functionality can be calibrated to improve its accuracy (e.g., at installation, periodically, upon occurrence of certain events, etc.). For example, a cable modem (CM) or set top box (STB) has its own internal frequency response which may obscure the frequency response of the cable system or portions thereof under measurement. Various techniques can be used to compensate for the self-response of the CM/STB. One approach is to measure the self-response during the manufacturing process. Another approach is to insert pilot signals that permit measurement of the self-response during operation, or during power-up.

FIG. 7is a diagram illustrating communication between communication devices110and120to generate spectrum analysis (SA) information. This diagram shows communication device110transmitting a signal with pilot tones (e.g., such as based on orthogonal frequency division multiplexing (OFDM) signaling) to communication device120at or during a first time. Then, the communication device120processed the received signal with the channel-affected pilot tones (shown as pilot tones'). The communication device120then determines SA information (e.g., a channel estimate, a frequency response, etc. of the communication channel between communication device110and communication device120). The communication device120may then transmit or provide this SA information to the communication device110for use in identifying an operational trend of the communication channel between devices110and120and any actual/existing or expected failures or degradation of that communication channel.

In one example of operation, these pilot tones or signals may be inserted by a CM or STB (CM/STB) itself, or anywhere in the plant from the headend (or CMTS) downward. In some cases, tilt compensation may be purposely inserted by the CM/STB ahead of the analog to digital converter (ADC), and this tilt compensation may obscure the tilt from the cable plant. It may be decided to compensate fully or partially and remove the internal or self-frequency-responses (e.g., self-response), or to leave it in place, depending on the application. Such compensation may be performed in the time or frequency domains. Leaving the self-response in place can show the total response experienced by a signal transmitted via that communication link. Alternatively, compensating for and removing the self-response is to permit the headend (or CMTS) to analyze the performance of the cable plant itself and perform fault isolation of the plant.

In addition, any of a number of SA user interface functions may be included within a given device to provide additional or alternative SA information (e.g., added in software, such as span, center frequency, start/stop frequencies, resolution bandwidth, video bandwidth (averaging), cursors, power between cursors, max hold, multiple traces, etc.).

Within a given communication device that includes an equalizer and equalizer coefficients, those downstream equalizer coefficients may also be queried and used to analyze the quality of the downstream signal. The equalizer coefficients give information on the channel response and the effect of the channel on the signal. The equalizer coefficients and SA capability provide further insight into the quality of the signal and can be used to isolate faults in the plant. Upstream pre-equalizer coefficients can also be examined and compared to the downstream equalizer coefficients, as often a fault in the cable plant will cause a change in both the upstream and downstream signals, and hence in both the upstream and downstream equalizer coefficients.

For multi-channel receivers (e.g., such as with reference toFIG. 4,FIG. 5), there can be a set of downstream equalizer coefficients for each receiver. For example, a 32-channel CM/STB can provide equalizer coefficients for each of its 32 channels. The responses at each channel can be combined to produce a clearer picture of what is happening to the signal across the band.

Also, if a spare downstream receiver (e.g., CM/STB) is available, it can be hopped to different frequencies, and at each frequency the equalizer coefficients can be obtained, thus giving a response across the band.

Moreover, certain examples have been described herein with respect to one particular type of communication system (e.g., cable plant and including SA functionality implemented within one or more user devices [CM, STB, etc.] implemented within the cable system). Note that such functionality may be extended towards any type of communication system having any of a number of different respective types of communication links implemented using any of a number of different types of communication media (e.g., wired, wireless, optical, etc.). Any one or more respective devices within the communication system may include SA functionality to perform acquisition, processing, analysis, reporting, etc. of any variety of types of SA information (e.g., frequency responses, channel estimates, changes of such parameters, etc.).

FIG. 8is a diagram illustrating an embodiment of a method800for execution by one or more communication devices. Method800begins by receiving spectrum analysis (SA) information from one or more devices in a communication system (block810). Operation continues by processing the SA information to determine an operational trend of one or more communication channels (block820). Based on the operational trend, method800operates by identifying any actual/existing or expected failure or degradation of the communication system (block830).

FIG. 9is a diagram illustrating another embodiment of a method900for execution by one or more communication devices. Method900begins by generating at least one operational trend of at least one element of the communication system (block910). Based on the at least one operational trend, the method900operates by identifying any actual/existing or expected failure or degradation of the at least one element of the communication system (block920).

In decision block930, the method900operates by determining whether any actual/existing or expected failure or degradation has been identified (e.g., if one or more conditions have been met that would indicate any actual/existing or expected failure or degradation).

If no actual/existing or expected failure or degradation is identified, then the method900continues operation of the communication system without modification (block950). Alternatively, if an actual/existing or expected failure or degradation is in fact identified, then the method900modified operation of the communication system without modification (block950). The method900may iterate or loop back continually based on monitoring of the communication system in attempts to identify additional actual/existing or future expected failures or degradations.

FIG. 10Ais a diagram illustrating another embodiment of a method1000for execution by one or more communication devices. Method1000begins by processing first SA information received from first communication device to generate first result (block1010). Method1000continues by processing second SA information received from second communication device to generate second result (block1020). Method1000then operates by combining to generate first result and second result to determine operational trend of communication within communication system (e.g., communication channel, communication device, etc.) (block1030).

FIG. 10Bis a diagram illustrating another embodiment of a method1001for execution by one or more communication devices. Method1001begins by processing first SA information received from communication device at first time to generate first result (block1011). Method1001then operates processing second SA information received from the same communication device communication device at a second time to generate second result (block1021). Method1001continues by combining to generate first result and second result to determine operational trend of communication within communication system (e.g., communication channel, communication device, etc.) (block1031).

The term “module” is used in the description of one or more of the embodiments. A module includes a processing module, a functional block, hardware, and/or software stored on memory for performing one or more functions as may be described herein. Note that, if the module is implemented via hardware, the hardware may operate independently and/or in conjunction with software and/or firmware. As also used herein, a module may contain one or more sub-modules, each of which may be one or more modules.

While particular combinations of various functions and features of the one or more embodiments have been expressly described herein, other combinations of these features and functions are likewise possible. The present disclosure of an invention is not limited by the particular examples disclosed herein and expressly incorporates these other combinations.