Patent Application
20080031386
Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents that may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be readily apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present invention.
Some portions of the detailed descriptions which follow are presented in terms of processes, procedures, logic blocks, functional blocks, processing, and other symbolic representations of operations on code, data bits, data streams or waveforms within a computer, processor, controller and/or memory. These descriptions and representations are generally used by those skilled in the data processing arts to effectively convey the substance of their work to others skilled in the art. A process, procedure, logic block, function, process, etc., is herein, and is generally, considered to be a self-consistent sequence of steps or instructions leading to a desired and/or expected result. The steps generally include physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical, magnetic, optical, or quantum signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer or data processing system. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, waves, waveforms, streams, values, elements, symbols, characters, terms, numbers, or the like, and to their representations in computer programs or software as code (which may be object code, source code or binary code).
It should be borne in mind, however, that all of these and similar terms are associated with the appropriate physical quantities and/or signals, and are merely convenient labels applied to these quantities and/or signals. Unless specifically stated otherwise and/or as is apparent from the following discussions, it is appreciated that throughout the present application, discussions utilizing terms such as “processing,” “operating,” “computing,” “calculating,” “determining,” “manipulating,” “transforming” or the like, refer to the action and processes of a computer or data processing system, or similar processing device (e.g., an electrical, optical, or quantum computing or processing device or circuit), that manipulates and transforms data represented as physical (e.g., electronic) quantities. The terms refer to actions and processes of the processing devices that manipulate or transform physical quantities within the component(s) of a circuit, system or architecture (e.g., registers, memories, other such information storage, transmission or display devices, etc.) into other data similarly represented as physical quantities within other components of the same or a different system or architecture.
Furthermore, in the context of this application, the terms “wire,” “wiring,” “line,” “signal,” “conductor” and “bus” refer to any known structure, construction, arrangement, technique, method and/or process for physically transferring a signal from one point in a circuit to another. Also, unless indicated otherwise from the context of its use herein, the terms “known,” “fixed,” “given,” “certain,” “predefined” and “predetermined” generally refer to a value, quantity, parameter, constraint, condition, state, process, procedure, method, practice, or combination thereof that is, in theory, variable, but is typically set in advance and is generally not varied thereafter when in use.
Similarly, for convenience and simplicity, the terms “clock,” “time,” “timing,” “rate,” “period” and “frequency” are, in general, interchangeable and may be used interchangeably herein, but are generally given their art-recognized meanings. Also, for convenience and simplicity, the terms “data,” “data stream,” “waveform” and “information” may be used interchangeably, as may (a) the terms “flip-flop,” “latch” and “register,” and (b) the terms “connected to,” “coupled with,” “coupled to,” and “in communication with,” (which may refer to direct or indirect connections, couplings, or communications) but these terms are generally given their art-recognized meanings herein.
Embodiments of the present invention pertain to methods, algorithms, architectures, circuits, and/or systems for robust signal detection for wireless communications. For example, a method of detecting a predefined signal pulse event in a wireless network device can include the steps of: (i) comparing a power of a received signal pulse to a predetermined power threshold of a predefined signal; (ii) determining a duration of the received signal pulse when the power of the received signal pulse is greater than the predetermined power threshold; and (iii) indicating an occurrence of the predetermined signal pulse event when the duration of the received signal pulse is between first and second predetermined duration thresholds of the predefined signal. The predefined signal pulse event can be a radar signal pulse, for example.
In another aspect of the invention, a method and/or algorithm of detecting a predefined signal in a wireless network device can include the steps of: (i) inserting a first logic level into an entry in an event table with a plurality of entries when an occurrence of a predefined signal pulse event is detected, or inserting a second logic level into the entry when the occurrence of the predefined signal pulse event is not detected; and (ii) repeating the inserting step for a next one of the plurality of entries. Further, the inserting step can be repeated until a logic level is entered a plurality of times in each of a plurality of columns. Then, a presence of the predefined signal can be indicated when a number of entries containing the first logic level in at least one column is greater than a threshold. The predefined signal can be a radar signal and the threshold can be a radar signal pulse number, for example.
In another aspect of the invention, a method and/or algorithm of detecting a predefined signal in a wireless network device can include the steps of: (i) changing a value of an entry in an event table with a plurality of entries when a predefined signal pulse event has been detected; (ii) repeating the changing step for a next one of the plurality of entries; and (iii) indicating that the predefined signal has been detected when one of the entry values reaches a threshold value. The predefined signal can be a radar signal and the threshold value can be zero, for example.
In another aspect of the invention, a physical layer device can include: (i) an event table with a plurality of entries arranged in a plurality of columns; (ii) a control circuit configured to modify one of the plurality of entries when a predefined signal pulse event is detected; and (iii) an indicator circuit configured to provide a predefined signal detection indication when one or a combination of the plurality of columns includes a predetermined value. The event table can also include a plurality of columns and the predefined signal can be a radar signal, for example.
The invention further relates to hardware implementations of the present architecture, method and circuit. Embodiments of the present invention can advantageously provide a reliable and simplified approach for radar signal detection suitable for wireless network devices. Further, embodiments of the present invention can advantageously provide for radar signal detection without the aid of a base band processor for determining whether the received signal is a packet. The invention, in its various aspects, will be explained in greater detail below with regard to exemplary embodiments.
According to various embodiments of the present invention, a mechanism or circuit for detecting radar signals may not require elimination of non-radar events corresponding to network traffic and/or additive noise. As a result, there may be no need for the aid of a base band processor for determining whether the received signal is a packet. Such radar detection independent of base band processing can make the network device and/or system more flexible. Thus, a detection scheme in accordance with embodiments of the present invention can be incorporated into any application that requires radar or other predefined signal detection, while the base band of this application may not need to provide traffic status to the detection mechanism. For example, radar detection processing can occur in a physical layer device and may not need to be off-loaded to another device for such base band processing.
In general, a robust radar detection scheme can achieve a high detection rate, while keeping the false alarm rate low. Several channel factors, such as a multipath environment, appreciably high network traffic, and/or noise (such as additive white Gaussian noise [AWGN]), can affect the detection performance. A multipath environment may affect the received radar pulse width and amplitude. In addition, the network traffic and/or a noisy channel may lead to higher false alarm rates by making the radar signal more difficult to detect when the radar signal power is significantly less than that of the network traffic and/or noise. As will be discussed in more detail below, thresholds can be determined to accommodate signals subjected to such effects.
An Exemplary Method of Detecting a Predefined Signal Pulse Event
An exemplary method of detecting a predefined signal pulse event in a wireless network device can include the steps of: (i) comparing a power of a received signal pulse to a predetermined power threshold of a predefined signal; (ii) determining a duration of the received signal pulse when the power of the received signal pulse is greater than the predetermined power threshold; and (iii) indicating an occurrence of the predetermined signal pulse event when the duration of the received signal pulse is between first and second predetermined duration thresholds of the predefined signal. The predefined signal pulse event can be a radar signal pulse, for example.
Referring now to
As discussed above, a radar signal pulse duration can be about 1 μsec, or from about 1 μsec-5 μsec, for example. However, after passing through a multipath channel environment, the received signal may have a pulse duration greater than 1 μsec. Accordingly, the two duration thresholds can be determined according to the known or expected duration of a transmitted pulse. The duration threshold X may be set slightly less than the expected pulse duration of a radar signal, for example 1 μsec. The duration threshold Y may be set equal to the maximum expected pulse duration of a radar signal propagating through a multipath environment, for example, 1.5 μsec. In one embodiment, duration threshold Y may be selected such that adverse multipath effects are reduced or minimized. The power threshold can be related to the minimum radar power level required to be detected, such as −62 dBm. In accordance with embodiments of the present invention, the predetermined power threshold can be set slightly higher than −62 dBm in order to reduce the rate of false positive detections.
Referring now to
Next in
Referring now to
Because different predefined signals (e.g., different radar signals) may have different burst lengths and/or PRFs, where such signals are to be detected, an event table corresponding to each such signal can be included. For example, FCC regulations include three different radar signals for detection by wireless network devices. Accordingly, three event tables may be used to accommodate the signals to be detected according to such FCC regulations using a device in accordance with embodiments of the present invention.
A First Exemplary Method of Detecting a Predefined Signal
An exemplary method and/or algorithm of detecting a predefined signal in a wireless network device can include the steps of: (i) inserting a first logic level into an entry in an event table with a plurality of entries when an occurrence of a predefined signal pulse event is detected, or inserting a second logic level into the entry when the occurrence of the predefined signal pulse event is not detected; and (ii) repeating the inserting step for a next one of the plurality of entries. Further, the inserting step can be repeated until a logic level is entered a plurality of times in each of a plurality of columns. Then, a presence of the predefined signal can be indicated when a number of entries containing the first logic level in at least one column is greater than a threshold. The predefined signal can be a radar signal and the threshold can be a radar signal pulse number, for example.
Referring now to
In
Once either the whole table or some predetermined number of rows, columns, and/or entries is filled up, a determination can be made as to whether a valid radar signal is present. For example, if the number of logic level “1” values in any column exceeds a pulse number threshold, a radar signal may be considered detected. In the particular example of
Alternatively, some combination of columns can be considered for the radar signal detection indication. For example, if a number of logic level “1” values in two adjacent columns exceeds a pulse number threshold, a radar signal detection can be made. Further, three, four, or more adjacent columns can be so combined for a radar signal detection consideration, particularly in relatively large tables. Such alternatives can be employed in a design trade-off involving detection accuracy and the prevention of false signal detections, for example. Such false signal detections may result from a multipath environment, significant network traffic, or channel noise, for example.
Referring now to
However, if no event is detected (606) for the given time slot or sampling window, a logic level “0” can be inserted into the corresponding entry in the event table (614). Either after: (i) each logic level “1” is inserted when an event is detected; (ii) a designated number of entries have been accessed; or (iii) a sufficient number of sampling windows has passed, it can be determined if a number of “1” entries in any column or combination of columns (e.g., two adjacent columns) exceeds a pulse number threshold (610). If such a pulse number threshold has been exceeded (612), an indication can be made that a predefined signal has been detected (618) and the flow can complete (620).
On the other hand, if the pulse number threshold has not been exceeded (612) after checking the number of “1” entries in any column or combination of columns, a next position along a row in the event table can be accessed (616). This next position can also be accessed after a logic level “0” is inserted (614) when no event is detected for a given time slot, as discussed above. Once a position is changed to a next position in the event table, the flow can return to receive possible predefined signals (604).
The next position can be from left to right along a row of an event table until an entire row has been filled or accessed, then the next position can be the leftmost position in the next row down. This flow to a next position in an event table can either continue seamlessly or a reset/initialization sequence can occur once the event table has been completely filled, or a predefined signal has been detected. Such a reset or initialization state of each entry in the event table can either be the logic level “0” or some third value (e.g., other than a logic level “0” or “1”), for example.
As discussed above, a different event table can be used for each predefined (e.g., radar) signal to be detected in accordance with embodiments of the present invention. Whenever all, or a subset of, the event tables designated for given radar signals are filled up or a sufficient number of entries in each table have been accessed, a check can be performed for each column or appropriate combination of columns for each table. Further, while FCC regulations do not require a report as to the specific types of radar signals detected, the detection scheme in accordance with embodiments of the present invention can also be used to distinguish radar signal types. This distinction can be made by a mapping to a particular event table through which a radar signal detection has been made. Further, as discussed above, a radar signal can be reported as detected as soon as the number of ones in any column, or designated combination of columns, exceeds a pulse number threshold. Accordingly, the flow does not require waiting until a full event table or all such tables included are checked, but rather the detection flow can proceed until sufficient entries in designated columns in any event table have reached a minimum number of “1” values.
In this fashion, one or more event tables can be used to detect one or more distinct types of predefined signals, such as radar signals. Each entry in each table can correspond to the detecting or non-detecting of a predefined signal pulse event in a particular time slot or sampling window. Once a number of entries indicating such event detections in one or more columns have been found, a predefined signal may be indicated as detected. Further, the particular type of predefined signal detected can correspond to the event table through which the detection has been made, thus allowing for distinguishing of the predefined signal types.
A Second Exemplary Method of Detecting a Predefined Signal
An exemplary method and/or algorithm of detecting a predefined signal in a wireless network device can include the steps of: (i) changing a value of an entry in an event table with a plurality of entries when a predefined signal pulse event has been detected; (ii) repeating the changing step for a next one of the plurality of entries; and (iii) indicating that the predefined signal has been detected when one of the entry values reaches a threshold value. The predefined signal can be a radar signal and the threshold value can be zero, for example.
Referring now to
In
Once a predefined signal pulse event occurs, a value of a corresponding entry in an event table can be changed. In the particular example shown in
Referring now to
However, if no such event is detected (806) for the given time slot or sampling window, no change can be made to the corresponding entry in the event table and the position in the event table can change to a next position in the row in the event table (812) and possible predefined signals can be received (804) for the next sampling window. However, if such an event has been detected (806), an entry in the event table corresponding to the current time slot or sampling window can be decremented (808).
For each such changing or decrementing of an entry value upon the detection of a predefined signal pulse event, a check can be performed to determine if any entries are equal to a PN threshold (810). Further, values in adjacent columns may also be summed and compared against such a predetermined value. In one example, the PN threshold may be chosen to be zero. If any entries are zero (810), an indication that a predefined signal has been detected can be made (814) and the flow can complete (816). However, if no such entries hold a zero value (810), the position in the event table can change to a next position in the row in the event table (812) and possible predefined signals can be received (804) for the next sampling window.
The next position as described above (e.g., in box 812) can be from left to right along the row of an event table (e.g., 702), and may continue for some predetermined number of passes through the row or until a predefined signal has been detected. Further, a reset or initialization sequence (e.g., to return each entry value to a pulse number threshold value) can occur once some predetermined number of passes through the row have been completed, when a predefined signal has been detected, or as part of a periodic reset function, for example.
As discussed above, a different event table can be used for each predefined (e.g., radar) signal to be detected in accordance with embodiments of the present invention. Whenever a column in one such event table has a value equal to the PN threshold, an indication that the particular type of radar signal corresponding to that event table is present can be made. Further, while FCC regulations do not require a specific radar signal type report, but rather only detection of any such radar signals regardless of the signal type, the detection scheme in accordance with embodiments of the present invention can also be used to distinguish between radar signal types. This distinction can be made by mapping to a given event table through which a radar signal detection has been made.
In this fashion, one or more event tables can be used to detect one or more distinct types of predefined signals, such as radar signals. Each entry in each table can correspond to the detection or non-detection of a predefined signal pulse event in a particular time slot or sampling window. Once any entry indicating a number of such event detections (e.g., via decrementing values) in any column has been found, a predefined signal may be indicated as detected. Further, the particular type of predefined signal detected can correspond to the event table through which the detection has been made, thus allowing for distinguishing of the predefined signal types.
An Exemplary Device for Detecting a Predefined Signal
An exemplary physical layer device for detecting a predefined signal can include: (i) an event table with a plurality of entries arranged in a plurality of columns; (ii) a control circuit configured to modify one of the plurality of entries when a predefined signal pulse event is detected; and (iii) an indicator circuit configured to provide a predefined signal detection indication when one or a combination of the plurality of columns includes a predetermined value. The event table can also include a plurality of columns and the predefined signal can be a radar signal, for example.
Such a physical layer device can include processing circuitry and/or other means for detection of a radar signal as described above, for example. As such, no base band processing for determining whether a received signal is a packet or not may be required in accordance with embodiments of the present invention. Further, the physical layer device can include more than one event table, with a different event table being used for each radar signal to be detected in the device. Such event tables can be one or a combination of, the exemplary table types as shown in
Referring now to
Logic & sampling circuitry 906 can include circuits configured to implement predefined signal event detection (e.g., as in
In this fashion, one or more event tables can be used to detect one or more distinct types of predefined signals, such as radar signals, in a physical layer device. Further, the particular type of predefined signal detected can correspond to the event table through which the detection has been made, thus allowing for distinguishing of the predefined signal types.
While the above examples primarily include radar signal detection approaches, one skilled in the art will recognize that other predefined signals may also be detected in accordance with embodiments. Further, one skilled in the art will recognize that other variations of the exemplary event tables described herein may also be used in accordance with embodiments.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.
