US20170207935A1 - System, device, and method for shaping transmit noise - Google Patents
System, device, and method for shaping transmit noise Download PDFInfo
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- US20170207935A1 US20170207935A1 US15/043,067 US201615043067A US2017207935A1 US 20170207935 A1 US20170207935 A1 US 20170207935A1 US 201615043067 A US201615043067 A US 201615043067A US 2017207935 A1 US2017207935 A1 US 2017207935A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03828—Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties
- H04L25/03834—Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties using pulse shaping
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/0003—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain
- H04B1/0028—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain wherein the AD/DA conversion occurs at baseband stage
Abstract
Description
- The present application claims the benefit of the earlier filing date of U.S. provisional application 62/279,416 having common inventorship with the present application and filed in the U.S. Patent and Trademark Office on Jan. 15, 2016, the entire contents of which being incorporated herein by reference.
- Technical Field
- The present disclosure relates to software defined radio (SDR), specifically a device, system, and method for shaping transmit noise with SDRs.
- Description of the Related Art
- Software defined radio (SDR) provides the opportunity to develop fully programmable wireless communication systems, effectively supplanting conventional radio technologies, which typically have the lowest communication layers implemented in primarily in fixed, custom hardware circuits. In addition, transmit noise that is produced when signals are generated at the transmitter can cause degradation of the transmitted signal, which reduces the performance of the radio. In some instances, the transmit noise results in reduced spectral efficiency and increased distance between frequency channels.
- A more complete appreciation of this disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
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FIG. 1 is an exemplary illustration of a software defined radio (SDR) architecture, according to certain embodiments; -
FIG. 2 is an exemplary diagram of a hardware and logic configuration of a computing device, according to certain embodiments; -
FIG. 3 is an exemplary diagram of a radio controller and a RF front end, according to certain embodiments; -
FIG. 4 is an exemplary flowchart of a noise shaping process, according to certain embodiments; -
FIG. 5 is an exemplary flowchart of a gained spectrum allocation process, according to certain embodiments; -
FIG. 6 is an exemplary flowchart of a carrier aggregation noise shaping process, according to certain embodiments; -
FIG. 7 is an exemplary diagram of a transmitter, according to certain embodiments; -
FIG. 8 is an exemplary diagram of a wireless communication system, according to certain embodiments; -
FIG. 9 is an exemplary diagram of a wireless communication system, according to certain embodiments; and -
FIG. 10 is an exemplary flowchart of a noise shaping process, according to certain embodiments. - In the drawings, like reference numerals designate identical or corresponding parts throughout the several views. Further, as used herein, the words “a,” “an” and the like generally carry a meaning of “one or more,” unless stated otherwise.
- In an exemplary implementation, a device includes circuitry configured to determine noise shaping parameters for one or more transmit signals on one or more transmit channels based on transmission protocol and spectral mask criteria, identify frequency positions for the one or more transmit channels based on the noise shaping parameters, and apply the noise shaping parameters to the one or more transmit signals.
- In another exemplary implementation, a method includes determining noise shaping parameters for one or more transmit signals on one or more transmit channels based on transmission protocol and spectral mask criteria; identifying frequency positions for the one or more transmit channels based on the noise shaping parameters; and applying the noise shaping parameters to the one or more transmit signals.
- In another exemplary implementation, a device includes circuitry configured to determine sampling rates for one or more transmit signals based on predetermined signal and noise specifications for the one or more transmit signals, modulate the one or more transmit signals simultaneously within a predefined frequency spectrum, and adaptively modify at least one of the sampling rates or frequency bands of the one or more transmit signals based on properties of a transmit channel or a receiver.
- Aspects of the present disclosure are directed to implementing software defined radio (SDR) in transmitter applications by shaping transmit noise to minimize the impact of a channel on adjacent channels. By reducing the impact of transmit noise on the channel, less expensive transmitters can be used. In addition, transmission channels can be positioned closer together by deliberately shaping the transmit noise. The SDR may use spectral masks to shape the transmit noise. The transmit noise shaping can also be used in real simultaneous dual band (RSDB) and carrier aggregation applications.
- Implementations disclosed herein present a fully programmable software defined radio (SDR) platform and system able to be implemented on general-purpose computing devices, including personal computer (PC) architectures. Implementations of the SDR herein combine the performance and fidelity of general-purpose processor (GPP) SDR platforms. In addition, implementations of the SDR herein may use both hardware and software components and techniques to perform the processes described herein.
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FIG. 1 illustrates an exemplary architecture of an SDR platform andsystem 100 according to some implementations herein. The SDR platform andsystem 100 includes one ormore processors 102 that may be multi-core processors according to some implementations. Eachcore 104 includes one or more corresponding onboardlocal caches 106 that are used by the corresponding 104 during processing. Additionally, theprocessor 102 may also include one or more sharedcaches 108 and abus interface 110. Examples of suitable multi-core processors include the Xenon™ processor available from Intel Corporation of Santa Clara, Calif., USA, and the Phenom™ processor available from Advanced Micro Devices of Sunnyvale, Calif., USA, although implementations herein are not limited to any particular multi-core processor. In addition, theprocessor 102 may be reprogrammable hardware such as Field Programmable Gate Arrays (FPGA), or even dedicated hardware engines. In one example illustrated, one or more cores can be allocated for performing processing for the SDR, while other remaining cores can perform processing for other applications, the operating system, or the like. Further, in some implementations, two ormore processors 102 can be provided, andcores 104 across the two ormore processors 102 can be used for SDR processing. Throughout the disclosure, theprocessors 102 can interchangeably be referred to as processing circuitry or circuitry. - The
processor 102 is in communication viabus interface 110 with a high-throughput, low-latency bus 112, and thereby to asystem memory 114. Thebus 112 may be a PCIe bus or other suitable bus having a high data throughput with low latency. Further, thebus 112 is also in communication with aradio controller 116. As is discussed further below, theradio controller 116 may be coupled to an interchangeable radio front end (RF front end) 118. TheRF front end 118 is a hardware module that receives and/or transmits radio signals through an antenna (not shown inFIG. 1 ). In some implementations of the SDR architecture herein, theRF front end 118 represents a well-defined interface between the digital and analog domains. For example, in some implementations, theRF front end 118 may include analog-to-digital (A/D) and digital-to-analog (D/A) converters, and necessary circuitry for radio frequency transmission, as is discussed further below. - During receiving, the
RF front end 118 acquires ananalog RF waveform 120 from the antenna, possibly down-converts the waveform to a lower frequency, and then digitizes the analog waveform into discretedigital samples 122 before transferring thedigital samples 122 to theradio controller 116. During transmitting, theRF front end 118 accepts a stream of software-generateddigital samples 122 from a software radio stack 124 (i.e., software that generates the digital samples, as discussed below), and synthesizes the correspondinganalog waveform 120 before emitting thewaveform 120 via the antenna. Since all signal processing is done in software on theprocessor 102, the design ofRF front end 118 can be rather generic. For example, theRF front end 118 can be implemented in a self-contained module with a standard interface to theradio controller 116. Multiple wireless technologies defined on the same frequency band can use the same RFfront end hardware 118. Furthermore, various differentRF front ends 118 designed for different frequency bands can be coupled toradio controller 116 for enabling radio communication on various different frequency bands. Therefore, implementations herein are not limited to any particular frequency or wireless technology. - According to some implementations herein, the
radio controller 116 is a PC interface board optimized for establishing a high-throughput, low-latency path for transferring high-fidelity digital signals between theRF front end 118 andmemory 114. The interfaces and connections between theradio front end 118 andmulti-core processor 102 can enable sufficiently high throughput to transfer high-fidelity digital waveforms. Accordingly, to achieve a predetermined system throughput, some implementations of theradio controller 116 use a high-speed, low-latency bus 112, such as PCIe. With a maximum throughput of 64 Gbps (e.g., PCIe x32) and sub-microsecond latency, PCIe is easily able to support multiple gigabit data rates for sending and receiving wireless signals over a very wide band or over many MIMO channels. Further, the PCIe interface is typically common in many conventional general-purpose computing devices. Theradio controller 116 can also be a dedicated hardware bus connection, and may even be co-located with theprocessor 102 and theRF front end 118. - One role of the
radio controller 116 is to act as a bridge between the synchronous data transmission at theRF front end 118 and the asynchronous processing on theprocessor 102. Theradio controller 116 implements various buffers and queues, together with a large onboard memory, to convert between synchronous and asynchronous streams and to smooth out bursty transfers between theradio controller 116 and thesystem memory 114. The large onboard memory further allows caching of pre-computed waveforms for quick transmission of the waveforms, such as when acknowledging reception of a transmission, thereby adding additional flexibility for software radio processing. - In addition, the
radio controller 116 provides a low-latency control path for software to control the RFfront end hardware 118 and to ensure that the RFfront end 118 is properly synchronized with theprocessor 102. For example, wireless protocols have multiple real-time deadlines. Consequently, not only is processing throughput a critical requirement, but the processing latency should also meet certain response deadlines. For example, some Media Access Control (MAC) protocols also require precise timing control at the granularity of microseconds to ensure certain actions occur at exactly pre-scheduled time points. Theradio controller 116 of implementations herein also provides for such low latency control. -
FIG. 2 illustrates an exemplary depiction of acomputing device 200 that can be used to implement the SDR implementations described herein, such as the SDR platform andsystem 100 described above with reference toFIG. 1 . In the implementations described further herein, thecomputing device 200 may be any hardware device that can perform wireless communications, such as a wireless access point or mobile device that can implement one or more wireless communication protocols, such as a base station, switch, router, user equipment (UE), and the like. Throughout the disclosure, the terms computing device and SDR can be used interchangeably. - The
computing device 200 includes one ormore processors 202, amemory 204, one or more mass storage devices ormedia 206, communication interfaces 208, and a display and other input/output (I/O)devices 210 in communication via asystem bus 212. In addition, thecomputing device 200 can also include one or more timer blocks 220 in order to provide a notion of time to the various components of thecomputing device 200.Memory 204 andmass storage media 206 are examples of computer-readable storage media able to store instructions whichcause computing device 200 to perform the various functions described herein when executed by the processor(s) 202. For example,memory 204 may generally include both volatile memory and non-volatile memory (e.g., RAM, ROM, or the like). Further,mass storage media 206 may generally include hard disk drives, solid-state drives, removable media, including external and removable drives, memory cards, Flash memory, or the like. Thecomputing device 200 can also include one ormore communication interfaces 208 for exchanging data with other devices, such as via a network, direct connection, or the like, as discussed above. The display and other input/output devices 210 can include a specific output device for displaying information, such as a display, and various other devices that receive various inputs from a user and provide various outputs to the user, and can include, for example, a keyboard, a mouse, audio input/output devices, a printer, and so forth. -
Computing device 200 further includesradio controller 214 and RFfront end 216 for implementing the SDR herein. For example,system bus 212 may be a PCIe compatible bus, or other suitable high throughput, low latency bus. Theradio controller 214 and the RFfront end 216 may correspond to theradio controller 116 and the RFfront end 118 described previously with reference toFIG. 2 , and as also described below, such as with reference toFIG. 3 . Furthermore, aradio control module 218 can include software instructions stored inmemory 204 or other computer-readable storage media for controlling operations onradio controller 214, as is described additionally below. Thecomputing device 200 described herein is only one example of a computing environment and is not intended to suggest any limitation as to the scope of use or functionality of the computer architectures that can implement the SDR herein. Neither should thecomputing device 200 be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in thecomputing device 200. - Furthermore, implementations of SDR platform and
system 100 described above can be employed in many different computing environments and devices for enabling a software-defined radio in addition to the example ofcomputing device 200 illustrated inFIG. 2 . Generally, many of the functions described with reference to the figures can be implemented using software, hardware (e.g., fixed logic circuitry), manual processing, or a combination of these implementations. The term “logic”, “module” or “functionality” as used herein generally represents software, hardware, or a combination of software and hardware that can be configured to implement prescribed functions. For instance, in the case of a software implementation, the term “logic,” “module,” or “functionality” can represent program code (and/or declarative-type instructions) that perform specified tasks when executed on a processing device or devices (e.g., CPUs or processors). The program code can be stored in one or more computer readable memory devices, such asmemory 204 and/ormass storage media 206, or other computer readable storage media. Thus, the methods and modules described herein may be implemented by a computer program product. The computer program product may include computer-readable media having a computer-readable program code embodied therein. The computer-readable program code may be adapted to be executed by one or more processors to implement the methods and/or modules of the implementations described herein. The terms “computer-readable storage media”, “processor-accessible storage media”, or the like, refer to any kind of machine storage medium for retaining information, including the various kinds of memory and storage devices discussed above. -
FIG. 3 illustrates an exemplary implementation of aradio controller 302 and RFfront end 304 that may correspond to theradio controller front end radio controller 302 includes functionality for controlling the transfer of data between the RFfront end 304 and asystem bus 306, such asbuses radio controller 302 includes a direct memory access (DMA)controller 310, abus controller 312, registers 314, an SDRAM controller 316, and anRF controller 318. Theradio controller 302 further includes afirst FIFO buffer 320 for acting as a first FIFO for temporarily storing digital samples received from RFfront end 304, and asecond FIFO buffer 322 for temporarily storing digital samples to be transferred to RFfront end 304. TheDMA controller 310 controls the transfer of received digital samples to thesystem bus 306 via thebus controller 312. SDRAM controller 316 controls the storage of data inonboard memory 324, such as digital samples, pre-generated waveforms, and the like. - The
radio controller 302 can connect to various different RF front ends 304. In some implementations, the RFfront end 304 includes anRF circuit 326 configured as an RF transceiver for receiving radio waveforms from anantenna 328 and for transmitting radio waveforms viaantenna 328. The RFfront end 304 further may include an analog-to-digital converter (ADC) 330 and a digital-to-analog converter (DAC) 332. As discussed previously, analog-to-digital converter 330 converts received radio waveforms to digital samples for processing, while digital-to-analog converter 332 converts digital samples generated by the processor to radio waveforms for transmission byRF circuit 326. Furthermore, it should be noted that implementations herein are not limited to any particularfront end 304, and in some implementations, the entirefront end 304 may be incorporated into theradio controller 302. Alternatively, in other implementations, analog-to-digital converter 330 and digital-to-analog converter 332 may be incorporated into theradio controller 302, and RFfront end 304 may merely have anRF circuit 326 andantenna 328. Other variations may also be apparent in view of the disclosure herein. - In the implementation illustrated in
FIG. 3 , theDMA controller 310 andbus controller 312 interface with the memory and processor on the computing device (not shown inFIG. 3 ) and transfer digital samples between theradio controller 302 and the system memory on the computing device, such asmemory software control module 218 discussed above with reference toFIG. 2 sends commands and reads radio controller states through radio controller registers 314. Theradio controller 302 further usesonboard memory 324 as well assmall FIFO buffers FPGA 308 to bridge data streams between the processor on the computing device and the RFfront end 304. When receiving radio waveforms, digital signal samples are buffered in on-chip FIFO buffer 320 and delivered into the system memory on the computing device when the digital samples fit in a DMA burst (e.g., 128 bytes). When transmitting radio waveforms, the largeradio controller memory 324 enables implementations of the radio controller manager module 218 (e.g.,FIG. 2 ) to first write the generated samples onto theradio controller memory 324, and then trigger transmission with another command to theradio controller 302. This functionality provides flexibility to the implementations of theSDR manager module 218 for pre-calculating and storing of digital samples corresponding to several waveforms before actually transmitting the waveforms, while allowing precise control of the timing of the waveform transmission. - In addition, the
radio controller 302 provides the flexibility to be able to shape transmit noise for multiple transmit signals being modulated and transmitted simultaneously by at least one RFfront end 304 transmitter. For example, processing circuitry of theradio controller 302 can simultaneously modulate multiple transmit signals with multiple transmission protocols within a given spectrum with various noise shaping parameters that can reduce interference between transmit channels, reduce interference between devices, and reduce an amount of hardware associated with the RFfront end 304. In some implementations, the transmitter of theSDR 200 can use direct sampling and/or heterodyne methods to modulate and transmit signals through a transmission channel. Details regarding implementations of noise shaping with SDR are discussed further herein. - In SDR implementations, functionality of some radio components is achieved through execution of one or more software processes by the processing circuitry of the
processor 202 rather than through dedicated hardware components, which can be referred to as software defined components. For example, the filter components, and digital signal processor may be software defined components of the SDR. In addition, some of the components of the RFfront end 216 can also be executed as software defined components and/or are configured by the software defined components. For example, the configuration of the ADCs of the receiver can be modified by control signals issued by the processing circuitry. -
FIG. 4 is an exemplary flowchart of anoise shaping process 400, according to certain embodiments. When signals are produced and transmitted by the RFfront end 216, transmit noise can be introduced into the signal through various sources, such as quantization errors that are introduced at the DAC. In some implementations, SDR can be used to determine and/or modify sampling rates, configurations of the RFfront end 216, frequency locations of transmit channels and other parameters that affect noise shaping based on characteristics of types of signals being transmitted by theSDR 200, types of receivers within a predetermined distance of theSDR 200, and how the transmit signals impact other circuits within a predetermined distance of theSDR 200. By adaptively updating noise shaping parameters, theSDR 200 is able to improve efficiency of use of a transmission frequency spectrum so that a signal-to-noise ratio (SNR) of the transmit signals is increased and bit error rate (BER) is improved. Improving the efficiency of use of the transmission frequency spectrum also increases an amount of additional spectrum bandwidth available for modulating additional transmission signals. In addition, improving transmit signal quality through noise shaping allows power consumption and cost of the RFfront end 216 to be reduced. In addition, thenoise shaping process 400 can be applied to SDRs that are installed in a wireless access point or a user equipment, such as a mobile device configured to operate with one or more wireless network protocols. - At step S402, signal specifications associated with one or more receivers within a predetermined communications distance of the transmitter are determined. In some implementations, the
SDR 200 can determine one or transmission signal types based on characteristics of the receivers within a predetermined communications distance of the transmitter. The predetermined communications distance may be based on an average range for transmission signals based on the transmission protocols and operating frequencies of the devices in communication with one another. TheSDR 200 can determine the transmission signal types based on transmission protocols of the receivers within the predetermined communications distance. For example, theSDR 200 can include an offline transceiver that scans a local spectrum environment for receiving devices with which to communicate, such as base stations, user equipments (UEs), switching devices, routers, and the like. In certain embodiments, theSDR 200 is connected to the receiving devices via a backhaul communications network and detects the receiving devices through the network. When a receiving device is detected, the processing circuitry can determine characteristics of the receiving device, such as a transmission protocol, frequency band, performance parameters associated with the receiving device (e.g., SNR, BER, etc.) associated with the receiving device. TheSDR 200 can then use the characteristics of the receiving device to determine a sampling rate, spectral mask, frequency band positions, and other noise shaping parameters. - At step S404, interference parameters associated with one or more circuits within a predetermined distance of the transmitter are identified. In some implementations, signals generated by the transmitter of the
SDR 200 can produce harmonics and/or noise that affect performance of circuits within a vicinity of the transmitter. The circuits may include additional RF front ends 304 associated with theSDR 200, other circuits located within thecomputing device 200, or communications devices connected to theSDR 200 via the backhaul network. TheSDR 200 can receive feedback from the other circuits via thebus 212 or the backhaul network that includes interference data, such as SNR, frequency and signal strength of harmonics from the transmitter that affect the other circuits, and the like. In addition, the additional devices can transmit interference signals to theSDR 200 via a wireless communication channel that include the interference parameters indicating how much impact the interference the transmit signals from theSDR 200 have on the additional devices. - At step S406, the processing circuitry adaptively determines noise shaping parameters for transmit signals based on the characteristics of the receivers determined at step S402 and interference parameters determined at step S404 and applies the noise shaping parameters to the transmit signals. The noise shaping parameters can include at least one of a sampling rate, noise shaping scheme, spectral mask data, error vector magnitude data, and the like. In some implementations where a direct sampling transmitter is used, the sampling rate determined by the processing circuitry of the
SDR 200 corresponds to a multiple of the Nyquist rate. - Once an oversampled signal is obtained, the
SDR 200 modifies the oversampled signal to achieve noise shaping of the signal. In one implementation, the oversampled signal can be modified via a noise shaping scheme that includes single-rate or multi-rate filter parameters. For a heterodyne transmitter, the processing circuitry can determine a noise-shaped baseband or intermediate frequency (IF) source with an upconversion mixer. In addition, the transmitter can apply an analog finite impulse response (FIR) filter by combining multiple delayed versions of an original transmit signal with analog weighting to implement the FIR filter with desired transfer function zeroes to noise shape the transmit signal. - According to certain embodiments, the processing circuitry of the
SDR 200 applies a spectral mask filter to the transmit signals to ensure that the transmit signals meet spectral mask criteria for one or more transmission protocols. The processing circuitry can also modify the transmit signals to ensure that error vector magnitude (EVM) specifications are met. For a multi-band transmitter, the processing circuitry of theSDR 200 can merge the spectral mask for multiple transmission protocols or frequency bands into a joint spectral mask filter and apply the joint spectral filter mask so that the transmit signals meet spectral mask specifications for multiple frequency bands or transmission protocols. Generating the joint spectral masks for multi-band transmissions reduces a number of transmission sources and can also reduce complexity and cost of filter circuitry. - In addition, the processing circuitry may selectively improve or apply the spectral masks for one or more frequency bands associated with one or more receivers to reduce an overall filter complexity and improve signal capacity of the transmitter. The processing circuitry of the
SDR 200 can improve spectral mask filters for frequency bands associated with one or more receivers within a predetermined distance of the transmitter. In addition, the processing circuitry can determine the number of selected spectral masks to improve based on an overall processing capacity of theprocessors 102. - At step S408, the processing circuitry of the
SDR 200 assigns the transmit signals to one or more frequency channels within a transmit signal spectrum. In some implementations, the noise shaping schemes applied to the transmit signals allow spacing between transmit frequency channels to be reduced because the noise shaping reduced an amount of inter-channel interference. The assignment of the transmit signals to the frequency channels can be adaptively determined based on a predetermined protocol. For example, the processing circuitry can assign the transmit signals to frequency bands based on operating parameters of a network for a particular wireless communications standard, such as IEEE 802.11, 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), LTE-Advanced (LTE-A), and the like. In addition, the frequency channel assignments can be made based on an observation of a local spectrum with an associated receiver. The processing circuitry can also determine the frequency channel spacing and assignments based on a combination of the operating parameters for the network and the local spectrum analysis. In some implementations, step S408 may be performed prior to step S406. - In some implementations, the
noise shaping process 400 can be also be applied to real simultaneous dual band (RSDB) signals where two transmit signals at different frequencies can be noise shaped and modulated simultaneously via one DAC, which reduces costs of the RFfront end 216 while maintaining a performance level that corresponds to the performance of conventional RSDB applications. -
FIG. 5 is an exemplary flowchart of a gainedspectrum allocation process 500, according to certain embodiments. When the noise shaping parameters are applied to the transmit signals, additional signal spectrum may be unused, which may allow additional transmit signals to be modulated onto additional frequency channels of the transmit spectrum. Modulating additional transmit signals onto the additional frequency channels can increase efficiency of the transmitter of theSDR 200 without increasing hardware and bandwidth costs. - At step S502, the processing circuitry determines an amount of gained signal spectrum based on the application of the noise shaping parameters at step S406 and the frequency channel assignments at step S408 of the
noise shaping process 400. In some implementations, the processing circuitry of theSDR 200 calculates the amount of used frequency spectrum for the transmit signals prior to the application of the noise shaping parameters at step S406 and the frequency channel assignments at step S408 of thenoise shaping process 400. - At step S504, the processing circuitry determines whether the amount of gained signal spectrum is greater than a predetermined threshold. In some implementations, the predetermined threshold corresponds to an average transmit signal bandwidth for one or more transmit protocols, an average transmit signal bandwidth of the transmit signals presently modulated onto the one or more transmit channels, and the like. If the amount of gained signal spectrum is greater than the predetermined threshold, resulting in a “yes” at step S504, then step S506 is performed. Otherwise, if the amount of gained signal spectrum is less than or equal to the predetermined threshold, resulting in a “no” at step S504, then the gained
spectrum allocation process 500 is terminated. - At step S506, additional transmit signals are allocated to the gained signal spectrum. In some implementations, the processing circuitry determines a number of additional transmit signals to allocate to the gained signal spectrum dividing the amount of gained signal spectrum by an average transmit signal bandwidth. In addition, the processing circuitry of the
SDR 200 can apply thenoise shaping process 400 to the additional transmit signals to improve a total SNR of transmit signals within the transmission frequency spectrum. -
FIG. 6 is an exemplary flowchart of a carrier aggregationnoise shaping process 600, according to certain embodiments. Carrier aggregation provides the ability to increase data transmission rates by using multiple channels and carriers in order to increase data throughput. Using theSDR 200 to transmit carrier aggregated signals allows the carrier aggregation transmit spectrum to be adaptively shaped based on a local spectrum environment, type of receiver, size of the transmit signal, and the like. - At step S602, the processing circuitry of the
SDR 200 determines a carrier aggregation scheme for one or more carrier aggregation transmit signals. For example, in some implementations, the carrier aggregation transmit signal channels can be modulated as intra-band signals where each of the transmit signals are modulated within a single frequency band. The intra-band transmit carrier aggregated transmit signals can be contiguously aligned where the transmit channels are immediately adjacent to one another or non-contiguously aligned where the transmit channels are separated by a predetermined amount of frequency spectrum. In addition, the carrier aggregation scheme can also be a an inter-band non-contiguous scheme where the transmit channels are separated into distinct frequency bands. In some implementations, the carrier aggregation scheme is based on an amount of spectrum available, number of available transceivers, and the like. For example, the non-contiguous intra-band or intra-band schemes are implemented with two or more transceivers, and the contiguous intra-band scheme can be implement with one or more transceivers. - At step S604, the processing circuitry determines an amount of transmit noise that interferes with adjacent channels for each carrier aggregated signal channel. In some implementations, the amount of transmit noise in the adjacent channels can be quantified by a SNR calculation.
- At step S606, the processing determines whether the amount of interfering transmit noise associated with each of the signal channels is greater than a predetermined threshold. If the amount of interfering transmit noise is greater than the predetermined threshold, resulting in a “yes” at step S606, then step S608 is performed. Otherwise, if the amount of interfering transmit noise is less than or equal to the predetermined threshold, resulting in a “no” at step S606, then step S610 is performed.
- At step S608, the processing circuitry determines and applies noise shaping parameters to the carrier aggregated signal channels to reduce the amount of interfering transmit noise with the adjacent signal channels. The noise shaping techniques and parameters applied to carrier aggregated signals correspond to the noise shaping techniques and parameters applied to other types of transmit signals as discussed previously with respect to step S406 of the
noise shaping process 400. - At step S610, the carrier aggregated signals are transmitted by the RF front end circuit via a digital-to-analog converter (DAC). For SDR implementations, the transmit signals are able to be modulated and transmitted simultaneously via a single DAC circuit.
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FIG. 7 is an exemplary diagram of atransmitter 700, according to certain embodiments. The transmitter is just one implementation of at least a portion of the RFfront end 216 that can be implemented in thecomputing device 200, and other types and structures of antennas can be used. Thetransmitter 700 can also be included as part of a full duplex or half-duplex transceiver that also includes circuitry associated with a receiver. Theprocessor 702 includes processing circuitry is one implementation of theprocessor 202 of the computing device and can perform the noise-shaping processes described previously herein. Theprocessor 702 can also implement the functions of the software defined components of thetransmitter 700, such as computing digital samples of the transmitted signal via a digital signal processor and frequency synthesizer. TheDAC 704,filter 706,power amplifier 708, andantenna 710 are included in the RFfront end 216 and transform the digital signal into an analog RF waveform that can be transmitted across a signal channel. -
FIG. 8 is an exemplary diagram of awireless communication system 800 on which any of the processes described previously can be implemented, according to certain embodiments. Thewireless communication system 800 includes anaccess point 802 with a digital transceiver that communicates with astation 808. Theaccess point 802 can represent any hardware device that allow wireless devices to connect to a wired or wireless network via a communications protocol, such as any of the IEEE 802.11 standards, 3GPP Long Term Evolution (LTE), LTE-Advanced (LTE-A), and any other wireless network standard. The access points may be included as circuitry associated with a base station, switch, router, user equipment (UE), and the like. - In some implementations, the
access point 802 includes one or more network layers, such as a network interface layer, media access control (MAC) layer, and physical (PHY) layer. The PHY layer of theaccess point 802 includes a SDR, which is an implementation of thecomputing device 200. Like thecomputing device 200, the SDR of theaccess points 802 can include processing circuitry to perform the methods described herein. The SDRs within the PHY layer allows theaccess points 802 to simultaneously sense a spectrum environment at a receivingPHY 806 while adaptively shaping transmit noise at a transmittingPHY 804. - Because the PHY layer includes the SDR, the transmitting
PHY 804 includes a digital mixer that introduces undesired artifacts into a signal transmission. For example, as seen ingraph 810 of a transmission spectrum bandwidth, a transmission from theaccess point 802 includes a transmittedsignal 816 at a frequency of interest as well as multiple unwanted noise spurs 818 that are generated by the mixer. As can be seen ingraph 812, the processing circuitry of thecomputing device 200 can perform noise dithering to convert the noise spurs 818 into awideband noise floor 820 where a total magnitude of the noise generated by the noise spurs 818 is reduced by spreading thespurs 818 into the wideband noise floor. In addition, the processing circuitry of thecomputing device 200 can also perform adaptive noise shaping to introduce nulls in the ditherednoise floor 820 at predetermined frequency locations based on spectrum knowledge from sensing performed by thereceiver PHY 806 any other knowledge source, such as network configuration data, protocol data, handoff messages, or the like. The SDR allows theaccess point 802 to simultaneously sense the spectrum environment and adaptively shape the transmit noise based on the sensed spectrum environment.Graph 814 illustrates transmission spectrum bandwidth with a shapednoise floor 822 and the transmittedsignal 816. - The
station 808 represents any hardware device that can wirelessly communicate with theaccess point 802 via one or more wireless communications protocols and can include base stations or UEs such as mobile electronic devices, laptops, tablets, or cell phones. Thewireless communication system 800 illustrated inFIG. 4 is just one implementation, and other implementations can include any number of access points and/or stations based on system infrastructure, capacity, or station density. -
FIG. 9 is an exemplary diagram of awireless communication system 900 on which any of the processes described previously can be implemented, according to certain embodiments. Thewireless communication system 900 is another implementation of thewireless communication system 800 that includes anaccess point 902 that communicates withstation 908 on a first frequency F1 as well as astation 910 that communicates with astation 912 on a second frequency F2. For example, the PHY layer of theaccess point 902 includes a SDR, which is an implementation of thecomputing device 200. Like thecomputing device 200, the SDR of theaccess points 902 can include processing circuitry to perform the methods described herein. The SDRs within the PHY layer allows theaccess points 902 to simultaneously sense a spectrum environment at a receivingPHY 906 while adaptively shaping transmit noise at a transmittingPHY 904. - For example, the receiving
PHY 906 can sense the broadband spectrum environment and determine that the frequency F2 is in use. The processing circuitry of thecomputing device 200 can also determine that the frequency F2 is in use or any other information regarding any other frequencies of interest based on one or more other knowledge sources, such as network configuration data, protocol data, handoff messages, or the like that can be received from stations or access points via a wireless network or backhaul communication network. In some implementations, the transmittingPHY 904 shapes the transmit noise to introduce nulls at predetermined frequency locations, such as at frequency F2.Graph 914 illustrates a transmission signal 916 from theaccess point 902 to thestation 908 along with shaped noise floor 918 with a null introduced at frequency F2 to allow for transmission of signal 920 from thestation 910 to thestation 912 without added noise at the frequency F2. Performing adaptive noise shaping with SDR makes communication devices such as the transceiver in theaccess point 902 as well as the transmitter in thestation 910 cheaper to implement because the shaped noise reduces complexity of processing received signals with noise present at one or more frequencies of interest. -
FIG. 10 is an exemplary flowchart of anoise shaping process 1000, according to certain embodiments. Thenoise shaping process 1000 is described with respect to thewireless communication system noise shaping process 1000 can be performed in combination with thenoise shaping process 400, the gainedspectrum allocation process 500, or carrier aggregationnoise shaping process 600. For example, nulls produced at predetermined frequency positions during thenoise shaping process 1000 allow transmission channels to be positioned more closely together in order to increase efficiency of spectrum use. - At step S1002, the processing circuitry of the
computing device 200 associated withaccess point 902 determines properties of digital artifacts produced by a digital mixer in the transmittingPHY 904 that can include frequency and magnitude of the noise spurs. For example, as seen ingraph 810 of a transmission spectrum bandwidth inFIG. 8 , a transmission from theaccess point 802 includes a transmittedsignal 816 at a frequency of interest as well as multiple unwanted noise spurs 818 that are generated by the mixer. - Referring back to
FIG. 10 , at step S1004, properties of the spectrum environment are determined, such as one or more frequencies that are used by one or more wireless system protocols. For example, the receivingPHY 906 can sense the broadband spectrum environment and determine that a frequency, such as the frequency F2 is in use. The processing circuitry of thecomputing device 200 can also determine that the frequency F2 is in use or any other information regarding any other frequencies of interest based on one or more other knowledge sources, such as network configuration data, protocol data, handoff messages, or the like that can be received from stations or access points via a wireless network or backhaul communication network. - At step S1006, the processing circuitry of the
computing device 200 performs dithering and/or noise shaping based on knowledge of the spectrum environment. In some implementations, both dithering and noise shaping are applied to the transmit noise when a dithered wideband noise floor magnitude is greater than a predetermined threshold. Also, the processing circuitry may only apply dithering when the dithered wideband noise floor magnitude is less than or equal to a predetermined threshold. In other implementation, both dithering and noise shaping are applied regardless of the magnitude of the wideband noise floor. - As discussed previously,
graph 812 inFIG. 8 shows that noise dithering can be performed to convert the noise spurs 818 into awideband noise floor 820 where a total magnitude of the noise generated by the noise spurs 818 is reduced by spreading thespurs 818 into the wideband noise floor. In addition, the processing circuitry of thecomputing device 200 can also perform adaptive noise shaping to introduce nulls in the ditherednoise floor 820 at predetermined frequency locations based on spectrum knowledge from sensing performed by thereceiver PHY 806 any other knowledge source, such as network configuration data, protocol data, handoff messages, or the like. The SDR allows theaccess point 802 to simultaneously sense the spectrum environment and adaptively shape the transmit noise based on the sensed spectrum environment.Graph 814 illustrates transmission spectrum bandwidth with a shapednoise floor 822 and the transmittedsignal 816. Also,graph 914 inFIG. 9 illustrates a transmission signal 916 from theaccess point 902 to thestation 908 along with shaped noise floor 918 with a null introduced at frequency F2 to allow for transmission of signal 920 from thestation 910 to thestation 912 without added noise at the frequency F2. - A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of this disclosure. For example, preferable results may be achieved if the steps of the disclosed techniques were performed in a different sequence, if components in the disclosed systems were combined in a different manner, or if the components were replaced or supplemented by other components. Additionally, an implementation may be performed on modules or hardware not identical to those described. Accordingly, other implementations are within the scope that may be claimed.
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