Patent Application
20150092825
1. Field
The present disclosure relates generally to communication systems, and more particularly, to a self-test of a wireless user equipment (UE).
2. Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems. These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level.
A user equipment (UE) has a transmitter and a receiver used for sending and receiving communication signals. To transmit data, a transmit chain of modules performs various transformations and modulations in both digital and analog domains before the signal is sent to the antenna for transmission over the wireless medium. Along the way, these various modules along with the transmit power amplifier introduce distortions to the original transmit signal. Other sources of error on the transmit chain that may be introduced include bad software, calibration error, and setting errors. In order to test the quality of the transmission signal for a particular UE, which accounts for the distortions introduced by the transmit chain, the UE is tested in the factory using test equipment that provides a reference signal as the benchmark for comparison and error assessment. Examples of such error measurements include an error vector magnitude (EVM) and an adjacent channel leakage ratio (ACLR). To determine EVM for example, a magnitude and phase error between ideal symbol location and measured symbol location is obtained after decimating the recovered waveform at the de-modulator output of the test box. Continuous monitoring of transmit EVM and factory testing for EVM performance requirements requires measurement of EVM of a transmitter while utilizing external instruments on a test bench. When testing a large volume of UE units, this is time consuming, costly and labor intensive.
In an aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The method comprises performing a self-test within a user equipment (UE) to determine transmit signal quality measurement and transmitter reconfiguration. The UE generates a transmit signal, retrieves the transmit signal in digital domain from the transmit chain and stores the transmit signal as a reference signal. The transmit signal is sent along the transmit chain, through a coupling at the antenna, and retrieved as a feedback signal in digital domain via a feedback loop. A processor correlates the stored reference signal to the feedback signal to correct time misalignment between the transmit chain and the feedback loop. The processor calculates a transmit signal quality value based on the correlation and spectrum analysis. As an example, the transmit signal quality value may be an error vector magnitude or an adjacent channel leakage ratio.
The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.
Several aspects of a user equipment (UE) used in telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.
By way of example, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.
Accordingly, in one or more example aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), compact disk ROM (CD-ROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Combinations of the above should also be included within the scope of computer-readable media.
As shown in
The processor 102 may calculate an EVM according to at least one of the following approaches. In a first aspect, the processor 102 may calculate the error vector between transmissions and may receive a modulated waveform without demodulation. In a second aspect, the processor may demodulate a received signal and obtain a signal constellation to calculate an EVM.
The processor 102 may also calculate an ACLR according to at least one of the following approaches. In a first aspect, the processor 102 may perform a power spectrum analysis, and may evaluate emission spectrum at a frequency offset and a frequency range according to standard specifications. In a second aspect, the processor 102 may filter the time domain signal waveform with a designed filter so that only a frequency range of interest is covered by a band pass filter. At various tuning filter outputs, filter output power may then represent either main signal power or the emission power, which can be used to calculate the ACLR.
The apparatus may include additional modules that perform each of the steps of the algorithm in the aforementioned flow charts of
The processing system 714 may be coupled to a transceiver 710. The transceiver 710 is coupled to one or more antennas 720. The transceiver 710 provides a means for communicating with various other apparatus over a transmission medium. During the self-test method of the present application, the transceiver 710 receives a feedback signal from the coupling at the one or more antennas 720, extracts information from the received signal, and provides the extracted information to the processing system 714, specifically the receiving module 604. In addition, the transceiver 710 receives information from the processing system 714, specifically the transmission module 610, and based on the received information, generates a signal to be applied to the one or more antennas 720. The processing system 714 includes a processor 704 coupled to a computer-readable medium/memory 706. The processor 704 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 706. The software, when executed by the processor 704, causes the processing system 714 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 706 may also be used for storing data that is manipulated by the processor 704 when executing software. The processing system further includes at least one of the modules 604, 606, 608, and 610. The modules may be software modules running in the processor 704, resident/stored in the computer readable medium/memory 706, one or more hardware modules coupled to the processor 704, or some combination thereof.
In one configuration, the apparatus 602/602′ for self-test includes means for correlating the feedback signal to a reference transmit signal to correct time misalignments between the transmit chain and the feedback loop, wherein the reference transmit signal is generated in digital domain at an input to a transmit chain. The apparatus 602/602′ for self test also includes means for estimating a transmit signal quality value based on the correlation. The aforementioned means may be one or more of the aforementioned modules of the apparatus 602 and/or the processing system 714 of the apparatus 602′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system 714 may include a transmit processor, a receive processor, and a controller/processor. As such, in one configuration, the aforementioned means may be the transmit processor, the receive processor, and the controller/processor configured to perform the functions recited by the aforementioned means.
It is understood that the specific order or hierarchy of steps in the processes/flow charts disclosed is an illustration of example approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes/flow charts may be rearranged. Further, some steps may be combined or omitted. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.” Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”
The present Application for Patent claims priority to Provisional Application No. 61/883,824, entitled “INTERNAL FEEDBACK BASED EVM MEASUREMENT” filed Sep. 27, 2013, and assigned to the assignee hereof and hereby expressly incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61883824 | Sep 2013 | US |
