Phase noise compensation in a wireless system

According to one configuration, a system includes a first wireless station in communication with a second wireless station. A phase noise predictor model such as associated with the first wireless station receives phase noise information. The phase noise information captures an estimate of: i) first phase noise associated with a first wireless station, and ii) second phase noise associated with a second wireless station. Based on the received phase noise information, the predictor produces phase noise adjustment information. The predictor applies the phase noise adjustment information to adjust (compensate) a signal of the first wireless station. Adjustment of the signal results in phase noise adjustment with respect to both the first phase noise associated with the first wireless station and the second phase noise associated with the second wireless station.

BACKGROUND

So-called Phase Noise (PN) is a common source of error in wireless systems operating at high carrier frequencies such as in millimeter-wave spectrum. In general, phase noise occurs due to imperfections at respective local oscillators at in a transmitter and a receiver. In a MIMO OFDM (Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing) system (for e.g., 5G New Radio), paging notification causes both a common phase error (CPE) (multiplicative factor) on the OFDM subcarriers, as well as inter-carrier interference (ICI) (additive component) among the subcarriers. Phase noise effects are exacerbated as a magnitude of the wireless carrier frequency increases.

A Rel-17 Study Item on extending NR (New Radio) operation to the frequency range 52.6 GHz-71 GHz has been in progress. This feature targets utilization of the very wide unlicensed and licensed spectrum bandwidths in this frequency range.

New OFDM numerologies, such as a subcarrier spacing of 960 kHz and 480 kHz, have been introduced for this frequency range in order to increase robustness against phase noise.

In NR, phase tracking reference signals (PT-RS or so-called Phase Tracking Reference Signals) have been introduced to facilitate phase noise estimation and compensation at a wireless receiver. Both DL (DownLink) and UL (UpLink) PT-RS transmissions can be configured to provide phase noise estimation.

In one conventional application, on the DL, PT-RS signals are allocated within the time-frequency resources used for PDSCH (Physical Downlink Shared Channel). On the UL, PT-RS signals are allocated within the time-frequency resources used for PUSCH (Physical Uplink Shared Channel). The time-domain and frequency-domain density of the PT-RS is set to either a default value or configured by higher layers. PT-RS signals are designed to not overlap or collide with demodulation reference signals (DM-RS).

Phase noise in a MIMO-OFDM system with Nttransmit antennas, Nrreceive antennas, and K subcarriers can be modeled as:
y=(Gr⊗Ir)H(Gt⊗It)x+w,
where y⊂CKNr×1is the received complex frequency-domain signal, the K×K matrices Grand Gtrepresent Rx-side and Tx-side phase noise, ⊗ is the Kronecker product operator, Irand Itare Nr×Nrand Nt×Ntidentity matrices, H⊂CKNr×KNt is a block-diagonal matrix representing the overall fading channel coefficients, X⊂CKNt×1is the transmitted signal vector, and W⊂CKNr×1is additive complex Gaussian noise.

Element (k,l) of Gtwith guard interval g and random phase θ can be written as

BRIEF DESCRIPTION OF EMBODIMENTS

There are deficiencies associated with conventional techniques of providing wireless connectivity. For example, phase noise compensation (especially on the receiver-side of a wireless station pair) is a complex procedure that requires estimation of phase noise from reference signals. In contrast to conventional techniques, embodiments herein propose several ways of providing novel phase noise pre-compensation at one or more wireless stations in a network environment. The phase noise pre-compensation as discussed herein can be implemented in any suitable frequency range. In one nonlimiting example embodiment, the phase noise compensation is implemented in a frequency range of 52 to 71 GHz.

In accordance with example embodiments, a system includes a first wireless station in communication with a second wireless station. A phase noise management resource such as associated with or implemented in the first wireless station receives observations that carry phase noise information. The received phase noise information provides an estimate of a combination of: i) first phase noise associated with a first wireless station, and ii) second phase noise associated with a second wireless station. Based on the received phase noise information, and determined common phase error, the phase noise management resource produces phase noise adjustment information. Via the phase noise adjustment information, the phase noise management resource adjusts one or more signals produced by the first wireless station. Adjustment of the one or more signals results in phase noise adjustment to both the first phase noise associated with the first wireless station and the second phase noise associated with the second wireless station.

In one embodiment, the phase noise adjustment provided by the phase noise management resource (based on the phase noise adjustment information and determined common phase error) alleviates the need for the second wireless station to implement phase noise adjustment. For example, the phase noise adjustment information implemented at the first wireless station provides at least partial phase noise correction for both the first phase noise associated with a first local oscillator in the first wireless station and the second phase noise associated with a second local oscillator in the second wireless station.

Further embodiments herein include, via the phase noise management resource in the first wireless station, receiving communications from the second wireless station. The second wireless station generates the phase noise information based on wireless communications received from the first wireless station.

Additionally, or alternatively, the phase noise management resource at the first wireless station generates the phase noise information via one or more wireless signals received from the second wireless station.

Further embodiments herein include, via the phase noise management resource, controlling a density of repeatedly transmitting a wireless reference (pilot) signal from the first wireless station to the second wireless station, or vice-versa, based on the phase noise information; samples of the wireless reference signal are used to derive samples of the phase noise information.

In one embodiment, the one or more phase noise management resources as discussed herein implement a predictor to determine an amount of phase noise (common phase error) associated with the wireless stations and corresponding clock (oscillator) signals. For example, in one embodiment, the predictor as discussed herein can be configured to include a phase noise estimator model. The predictor and corresponding coefficient generator derive a set of coefficients from the received phase noise information, apply the generated set of coefficients to a phase noise analyzer model; and generate the phase noise adjustment information from the phase noise estimator model.

In further example embodiments, the coefficient generator associated with the predictor repeatedly updates the set of coefficients based on samples of the phase noise information received over time. For example, for a first set of coefficients derived from a first sample of the phase noise information, the phase noise estimator applies the phase noise adjustment information to adjust one or more signals (such as phase noise adjustment information associated with sub-carrier frequencies of the one or more signals) for a duration of communicating multiple symbols from the first wireless station using the one or more adjusted phase noise compensated signals; for a second set of coefficients derived from a second sample of the phase noise information, the phase noise management resource applies a second phase noise adjustment information to adjust the one or more signals (such as associated with sub-carrier frequencies) for a duration of communicating multiple symbols from the first wireless station using the one or more adjusted phase noise compensated signals; and so on. Thus, repeatedly updated phase noise information is used to provide accurate phase noise pre-compensation over time.

Note that the phase noise information can be received from one or more resources. For example, in one embodiment, the phase noise management resource receives a first portion of the phase noise information from the first wireless station; the phase noise management resource receives a second portion of the phase noise information from the second wireless station.

In further example embodiments, the phase noise adjustment information adjusts a phase associated with one or more sub-carrier frequency signals based on a summation (common phase error) of the estimated first phase noise and the estimated second phase noise.

In further example embodiments, the signal of the first wireless station falls within a range between 50 and 80 GHz, although the signal can be any suitable magnitude as previously discussed.

Embodiments herein are useful over conventional techniques. For example, implementation of phase noise adjustment correction at a single wireless station, instead of multiple wireless stations, reduces or eliminates a need for complex phase noise circuitry in either or both the first wireless station and the second wireless station. In one embodiment, a first wireless station includes circuitry to determine a combination of phase noise associated with the first wireless station and a second wireless station. The first wireless station implements phase noise estimation and compensation, mitigating phase noise associated with both the first wireless station and the second wireless station. Alternatively, the second wireless station communicates detected phase noise information to the first wireless station that implements phase noise compensation. Yet further, the first wireless station can be configured to implement phase noise compensation based on first phase noise information generated by the first wireless station and second phase noise information generated by the second wireless station.

Note that any of the resources as discussed herein can include one or more computerized devices, wireless stations, mobile communication devices, servers, base stations, wireless communication equipment, communication management systems, controllers, workstations, user equipment, handheld or laptop computers, or the like to carry out and/or support any or all of the method operations disclosed herein. In other words, one or more computerized devices or processors can be programmed and/or configured to operate as explained herein to carry out the different embodiments as described herein.

One embodiment includes a computer readable storage medium and/or system having instructions stored thereon to facilitate phase noise (pre) compensation (adjustment). The instructions, when executed by computer processor hardware, cause the computer processor hardware (such as one or more co-located or disparately processor devices) to: receive phase noise information, the phase noise information capturing an estimate of common phase error such as associated with: i) first phase noise associated with a first wireless station, and ii) second phase noise associated with a second wireless station; based on the received phase noise information, produce a phase adjustment information (a.k.a., phase noise compensation information); and apply the phase adjustment information to adjust one or more signals of the first wireless station communicated to the second wireless station.

The ordering of the steps above has been added for clarity sake. Note that any of the processing steps as discussed herein can be performed in any suitable order. Other embodiments of the present disclosure include software programs and/or respective hardware to perform any of the method embodiment steps and operations summarized above and disclosed in detail below.

As discussed herein, techniques herein are well suited for use in the field of wireless technology supporting wireless communications. However, it should be noted that embodiments herein are not limited to use in such applications and that the techniques discussed herein are well suited for other applications as well.

Also, note that this preliminary discussion of embodiments herein (BRIEF DESCRIPTION OF EMBODIMENTS) purposefully does not specify every embodiment and/or incrementally novel aspect of the present disclosure or claimed invention(s). Instead, this brief description only presents general embodiments and corresponding points of novelty over conventional techniques. For additional details and/or possible perspectives (permutations) of the invention(s), the reader is directed to the Detailed Description section (which is a summary of embodiments) and corresponding figures of the present disclosure as further discussed below.

DETAILED DESCRIPTION

In accordance with general embodiments, a system includes a first wireless station in communication with a second wireless station. A phase noise predictor model such as associated with the first wireless station receives or generates phase noise information. The phase noise information captures an estimate of common phase error such as associated with: i) first phase noise associated with a first wireless station, and ii) second phase noise associated with a second wireless station. Based on the received phase noise information, via derivation of coefficients from the phase noise information, the predictor model produces phase noise adjustment information. An adjustor applies the phase noise adjustment information to adjust one or more signals of the first wireless station. Adjustment of the one or more signals (such as used to transmit data from the wireless base station to the user equipment) results in phase noise compensation with respect to both the first phase noise associated with the first wireless station and the second phase noise associated with the second wireless station, reducing overall phase noise error in the system.

As previously discussed, receiver-side phase noise compensation and removal is usually a complex procedure that requires estimation of phase noise statistics from reference signals, followed by CPE removal and/or ICI filtering. Embodiments herein include several methods for phase noise pre-compensation of a wireless transmitter (either wireless base station or UE). The application of phase noise compensation reduces phase noise associated with a combination of a clock (local oscillator) at the first wireless station and phase noise associated with a clock (local oscillator) at the second wireless station. In one embodiment, the wireless stations implement NR (New Radio) cooperation and compensation in a frequency range 52.6 GHz-71 GHz as the exemplary scenario.

Now, more specifically,FIG.1is an example diagram illustrating a wireless network environment and implementation of compensation according to embodiments herein.

In this example embodiment, the wireless network environment100includes wireless base station131(a first wireless station) and one or more instances of mobile devices (such as UE1, UE2, etc.).

During operation, the user equipment UE1establishes a respective wireless link127-1with the wireless base station131. Via the wireless communication link127-1, the wireless base station131provides the user equipment UE1access to network190(such as the Internet, cellular network, etc.).

In an uplink (a.k.a., upstream) direction, the wireless communication link127-1supports communications122from the user equipment UE1through the wireless base station131to the network190. In a downlink (a.k.a., downstream) direction, the wireless communication link127-1supports communications121from the network190through the wireless base station131to the user equipment UE1.

In one embodiment, the wireless base station131includes a communication management resource140to support, among other things, phase noise compensation as discussed herein. Depending on the embodiment, user equipment UE1includes communication management resource141supporting phase noise compensation as discussed herein. Additional details of the phase noise compensation are further discussed below.

Note that one embodiment includes implementation of phase noise pre-compensation in the case when the transmitter-side (such as wireless base station131) phase noise profile is known with high accuracy to the transmitter (e.g., base station), and the transmitter-side estimate of the receiver-side PN is imperfect.

In one embodiment, so-called UE-side (such as user equipment UE1) phase noise statistics (a.k.a., phase noise information) are obtained at the base station131using one or both of the following methods: i) via the communication management resource141, implementing phase noise estimation at the UE1via generation of phase noise information, which is communicated (fed back) over the wireless communication link127-1to the base station131on an uplink control information message (e.g., PUCCH, etc.); and/or ii) phase noise estimation and generation of phase noise information at the communication management resource140of the wireless base station131based on uplink communications (such as repeated PT-RS transmissions or other signals) from the user equipment, the reference signals capture the effect of UE transmit phase noise, and assuming that UE transmit phase noise on the uplink is statistically correlated with UE1phase noise associated with receiving data on the downlink from the wireless station131.

In further example embodiments, the transmitter-side phase noise characteristics are estimated based on knowledge of the corresponding local oscillator architecture and characteristics.

As further discussed herein, note further that, based on the knowledge of UE-side phase noise information, the base station131can be configured to select an appropriate time-frequency density configuration associated with communication of the reference signals such as PT-RS communicated on the downlink to the user equipment UE1. In other words, one or more of the wireless base station131and corresponding communication management resource140can be configured to: i) control a density of communicating wireless reference (pilot) signals in a downlink to the user equipment UE1depending on use by the user equipment UE1to generate phase noise information; ii) a density of communicating wireless reference (pilot) signals in an uplink to the wireless station131depending on system needs, and so on.

FIG.2is an example block diagram illustrating components of a wireless system and implementation of a phase noise estimator in a wireless station such as user equipment according to embodiments herein.

As shown in this example embodiment, the communication management resource140includes multiple resources.

Note that any of the resources as discussed herein can be implemented via hardware, software, or a combination of hardware and software. For example, the communication management resource140can be implemented via communication management hardware, communication management software, or a combination of communication management hardware and communication management software; the communication management resource141can be implemented via communication management hardware, communication management software, or a combination of communication management hardware and communication management software; phase noise predictor model260can be implemented as phase noise predictor model hardware, phase noise predictor model software, and phase noise predictor model hardware and phase noise predictor model software; phase adjustor240can be implemented as phase adjustor hardware, phase adjustor software, or a combination of phase adjustor hardware and phase adjustor software; phase noise estimator resource238-1or238-2can be implemented as phase noise estimator hardware, phase noise estimator software, or a combination of phase noise estimator hardware and phase noise estimator software; and so on.

In this example embodiment, the communication management resource140associated with the wireless station131includes oscillator201-1, generator211-1, transmitter220-1, receiver230-1, coefficient generator250, and phase noise predictor model260. Transmitter220-1in this example embodiment includes phase (noise) adjustor240.

The communication management resource141associated with the user equipment UE1includes oscillator201-2, generator211-2, receiver230-2, transmitter220-2, and phase noise estimator resource238-2.

In this example embodiment, the oscillator201-1(such as main clock) produces a frequency signal205-1supplied to the frequency generator211-1. The frequency signal205-1is susceptible to phase noise error, resulting in phase noise error including phase noise error PNE11(such as common phase noise error) and PNE12(such as non-correctable phase noise error).

The oscillator201-2produces a frequency signal205-2supplied to the frequency generator211-2. The frequency signal205-2is susceptible to phase noise, resulting in phase noise error including phase noise error PNE21(such as correctable phase noise error) and PNE22(such as non-correctable phase noise error).

Embodiments herein include providing phase noise compensation (such as correction) for the generally correctable phase noise error PNE11and phase noise error PNE21as further discussed herein.

More specifically, in this example embodiment, the phase adjustor240receives sub-carrier frequency signals239(such as sub-carrier frequency SCF1, sub-carrier frequency SCF2, sub-carrier frequency SCF3, . . . ) in the base-band supplied to the transmitter220-1. The sub-carrier frequencies in the base-band include phase noise error. The phase adjustor240also receives phase adjustment information270(negative of the detected common phase error PNE11and PNE21). As its name suggests, the phase adjustment information270adjusts (compensates) one or more signals associated with the wireless station131via the phase adjustment information270.

For example, in one embodiment, the phase adjustor240applies the phase adjustment information270(compensation information) to each of the sub-carrier frequencies239to produce phase noise compensated sub-carrier frequencies SCF1′, SCF2′, SCF3′, . . . . An example is shown inFIG.5.

Referring again toFIG.2, transmitter220-1uses the phase noise compensated sub-carrier frequency signals SCF1′, SCF2, SCF3′, etc., outputted from the phase adjustor240to produce one or more wireless signals communicated to the IDFT (Inverse Discrete Fourier Transform) function299-1. For example, the signal processor241receiving the phase noise compensated sub-carrier frequencies includes a first multiplier M1that modulates the sub-carrier frequency SCF1′ via data DATA1to produce a sequence of symbols pre-compensated via the phase noise compensated sub-carrier frequency SCF1′; the signal processor241includes a second multiplier M2that modulates the sub-carrier frequency SCF2′ via data DATA2to produce a sequence of symbols modulated via the sub-carrier frequency SCF2′; the signal processor241includes a third multiplier M3that modulates the sub-carrier frequency SCF3′ via data DATA3to produce a sequence of symbols modulated via the sub-carrier frequency SCF3′; and so on.

As further discussed herein, the communication management resource140of the wireless station131can be allocated any number of sub-carrier frequencies (such as 15 KHz bandwidth×12 sub-carrier frequencies per physical resource block) to support communications in corresponding resource elements of one or more resource blocks. The signal processor241can include any number of multipliers to modulate respective data (as symbols) onto signals communicated to the user equipment UE1.

In further example embodiments, the IDFT299-1receives the modulated signals produced by the multipliers M1, M2, etc., and produces corresponding signal121′ (time domain signal) encoded with the phase noise compensated signals received from multipliers.

As an alternative to providing phase noise compensation in the frequency domain via signal processor241, embodiments herein include applying phase noise compensation on the time domain via compensation of signal121′.

Multiplier247receives signal121′ and carrier frequency RF1-1(such as between 50-80 GHz or other suitable value) produced by the generator211-1. Multiplier247outputs wireless communications121(encoded or modulated with respective data) from the wireless station131over communication link127-1in the downlink direction to the communication management resource141associated with user equipment UE11.

In one embodiment, the phase adjustor240uses the phase adjustment information270as a basis to provide phase noise compensation (reducing phase noise error) to the one or more sub-carrier frequencies239or signals generated by the transmitter220-1. Based on application of the phase adjustment information, the phase adjustor240eliminates at least a portion (i.e., the CPE component) of phase noise associated with the sub-carrier frequencies239.

As previously discussed, the transmitter220-1uses data signals DATA1, DATA2, etc., (or pilot signals) to modulate the respective sub-carrier frequencies supporting communications121over the wireless communication link127-1to the user equipment UE1.

At the user equipment UE1, the generator211-2uses the frequency signal205-2as a basis to produce carrier frequency RF1-2(same RF carrier frequency as RF1-1) supplied to the receiver230-2. The receiver230-2demodulates the received communications121to produce complex base-band signals294(such as including encoded DATA1, DATA2, etc.) communicated from the wireless station131to the user equipment UE1. Via the base-band signals294, the DFT (Discrete Fourier Transform) function276-2produces modulated downlink data289for further processing and retrieval of corresponding data DATA1, DATA2, etc.

As further discussed herein, in addition to communicating data, the transmitter220-1transmits multiple reference signals such as PT-RS (Phase Tracking Reference Signal) signals, DM-RS (Demodulation Reference) signals, etc., via one or more sub-carrier frequencies in one or more different time slots of allocated resource blocks. As further discussed herein, the reference signals can be spread across time (multiple time slots or resource elements) and/or frequency domains (channels) to the user equipment UE1.

In this example embodiment, the phase noise estimator resource238-2monitors the received pilot reference signals (such as PT-RS signals, DM-RS signals, etc.) from the transmitter220-1and produces phase noise information245-2associated with receipt of the reference signals in communications121. Note that details of such reference signals used to produce the phase noise information245-2is further discussed below inFIGS.8-12.

Referring again toFIG.2, in further example embodiments, as previously discussed, the generator211-2uses the frequency signal205-2as a basis to produce one or more carrier frequency signals such as RF1-2. Transmitter220-2uses the carrier frequency RF1-2as a basis in which to communicate phase noise information245-2, uplink information, reference signals, etc., to the wireless station131(via communications122including the generated phase noise information245-2) transmitted over the uplink of the wireless communication link127-1to the communication management resource140of wireless station131for processing.

The receiver230-1demodulates the received communications122with the carrier frequency RF1-1(same frequency as RF1-2) to obtain the phase noise information245-2generated by the phase noise estimator resource238-2and transmitted from the user equipment UE1. In one embodiment, as previously discussed, such phase noise information245-2captures information about the total phase noise error (a.k.a., common phase error PNE11+PNE21) associated with the oscillators201-1and201-2.

In further example embodiments, the phase noise information245-2is stored in registers of the coefficient generator250. Based on the received phase noise information245-2and stored values, the coefficient generator250generates and supplies corresponding phase noise coefficients C1, C2, etc., to the phase noise predictor model260. Based on the recently generated phase noise information245-2and corresponding derived coefficients C1, C2, C3, etc., the phase noise predictor model260produces the phase adjustment information270.

In one embodiment, as its name suggests, the phase adjustment information270includes one or more phase adjustment settings (such as the detected phase noise error PNE11+PNE21) supplied to the phase adjustor240. To provide phase noise pre-compensation at the wireless station131, the phase adjustor240provides signal adjustments or compensation to remove respective phase noise error (common phase error such as PNE11+PNE21) from the signals121′ and subsequent communications121transmitted by the transmitter220-1of the wireless station131to the user equipment UE1.

As further discussed below inFIG.5, embodiments herein include one or more of providing phase noise adjustments (compensation) via phase adjustor240in the frequency domain. Alternatively, note that the phase noise compensation can be achieved in a time domain (such as via modification of signal121′) rather than in the frequency domain via signal processor241.

Thus, in one embodiment, the communication management resource140(such as a phase noise management resource) associated with or in the first wireless station131receives phase noise information245-2generated by the user equipment UE1. The received phase noise information245-2provides an estimate of a combination of common phase error associated with: i) first phase noise (PNE11) associated with the oscillator201-1of the wireless station131, and ii) second phase noise (PNE21) associated with the local oscillator of the user equipment UE1. In this example embodiment, as previously discussed, the phase noise information245-2is generated by the phase noise estimator resource238-2.

Based on the received phase noise information245-2, the communication management resource140produces phase noise adjustment information270(phase noise compensation information). Via the phase noise adjustment information270, the communication management resource140adjusts one or more signals associated with the wireless station131via phase adjustor240. As previously discussed, adjustment of the one or more signals (such as adjustment of one or more sub-carrier frequencies) results in phase noise adjustment to both a first portion of phase noise (such as phase noise PE11) associated with the first wireless station131and a portion of second phase noise (such as phase noise PE21) associated with the second wireless station UE1.

Note further that, in one embodiment, during a condition when the multipath channel does not change during an OFDM (Orthogonal Frequency Division Multiplexing) symbol, the following opportunities exist. For example, embodiments herein include a method that exploits correlation between CPE (common phase error) in adjacent OFDM symbols. As SCS increases (i.e., OFDM symbol duration decreases) the correlation of the common phase error (CPE) increases among adjacent OFDM symbols. Once a CPE estimate (such as estimate of PNE11and PNE21) is obtained via phase noise information245-2, it is fed forward to a few upcoming OFDM symbols.

In further example embodiments, a receiver side predictive method (such as implemented by the phase noise estimator resource238-2exploits correlation between CPE (Common Phase Error) in adjacent OFDM symbols. Prediction can be employed, as a refinement of the above, with the state of the predictor re-actualized every few OFDM symbols.

Further embodiments herein include a base station side predictive method that exploits correlation between CPE in adjacent OFDM symbols. For example, in one embodiment, the mobile communication device UE1can be configured to send CPE estimates to the wireless base station131via wireless communications such as PUCCH (Physical Uplink Control Channel) communications or other suitable channel(s). The base station131implements the prediction and the predictor state update. The base station131optionally applies CPE correction pre-receiver-FFT in the symbols that carry data, but not on symbols that carry reference signals, e.g. CSI-RS.

An example is a simple autoregressive predictor of the form:
G(l+1)=Σn=1NanG(l−n)+e(l)

where the predictor is for either the receiver-side PN or the equivalent end-to-end PN, and the N filter coefficients an are the optimization parameters, and e(t) is residual white noise.

FIG.3is an example block diagram illustrating components of a wireless system and implementation of a phase noise estimator in a wireless station (such as a wireless base station) according to embodiments herein.

As shown in this example embodiment, the communication management resource140includes multiple resources.

In this example embodiment, the communication management resource140associated with the wireless station131includes oscillator201-1, generator211-1, transmitter220-1, receiver230-1, coefficient generator250, and phase noise predictor model260. Transmitter220-1in this example embodiment includes phase adjustor240.

The communication management resource141associated with the user equipment UE1includes oscillator201-2, generator211-2, receiver230-2, transmitter220-2, and phase noise estimator resource238-2.

In this example embodiment, the oscillator201-1(such as main clock) produces a frequency signal205-1supplied to the frequency generator211-1. The frequency signal205-1is susceptible to phase noise, resulting in phase noise error including phase noise error PNE11(such as correctable phase noise error) and PNE12(such as non-correctable phase noise error).

The oscillator201-2produces a frequency signal205-2supplied to the frequency generator211-2. The frequency signal205-2is susceptible to phase noise, resulting in phase noise error including phase noise error PNE21(such as correctable phase noise error) and PNE22(such as non-correctable phase noise error).

Embodiments herein include providing phase noise compensation (such as correction) for the generally correctable phase noise error PNE11and phase noise error PNE21as further discussed herein.

More specifically, as previously discussed, the phase adjustor240receives sub-carrier frequency signals239(such as sub-carrier frequency SCF1, sub-carrier frequency SCF2, sub-carrier frequency SCF3, . . . ) supplied to the transmitter220-1. The phase adjustor240also receives phase adjustment information270(negative of the detected common phase error PNE11and PNE21). As its name suggests, the phase adjustment information270adjusts a respective phase associated with one or more signals associated with the wireless station131.

For example, in one embodiment, the phase adjustor240applies the phase adjustment information270(compensation information) to each of the sub-carrier frequencies239to produce phase noise compensated sub-carrier frequencies SCF1′, SCF2′, SCF3, . . . . An example is shown inFIG.5.

Referring again toFIG.3, transmitter220-1uses the phase noise compensated sub-carrier frequency signals SCF1′, SCF2, SCF3′, etc., to produce one or more wireless signals communicated to the IDFT (Inverse Discrete Fourier Transform) function299-1. For example, the signal processor241includes a first multiplier M1that modulates the sub-carrier frequency SCF1′ via data DATA1to produce a sequence of symbols modulated via the phase noise compensated sub-carrier frequency SCF1′. The signal processor241includes a second multiplier M2that modulates the sub-carrier frequency SCF2′ via data DATA2to produce a sequence of symbols modulated via the sub-carrier frequency SCF2′; and so on. As further discussed herein, the communication management resource140of the wireless station131can be allocated any number of sub-carrier frequencies (such as 15 KHz bandwidth×12 sub-carrier frequencies per base resource block) to support communications in corresponding resource elements of one or more resource blocks.

The IDFT299-1receives the modulated signals produced by the multipliers M1, M2, etc., and produces corresponding signal121′ (time domain signal).

Multiplier247receives signal121′ and carrier frequency RF1-1produced by the generator211-1. Multiplier247outputs wireless communications121from the wireless station131over communication link127-1in the downlink direction to the communication management resource141associated with user equipment UE11.

In one embodiment, the phase adjustor240uses the phase adjustment information270as a basis to provide phase noise compensation (reducing phase noise error) to the one or more sub-carrier frequencies239. Based on application of the phase adjustment information, the phase adjustor240eliminates at least a portion of phase noise associated with the sub-carrier frequencies239and/or corresponding signals communicated from the wireless station131to the user equipment UE1.

As previously discussed, the transmitter220-1uses data signals DATA1, DATA2, etc., (or pilot signals) to modulate the respective sub-carrier frequencies supporting communications121over the wireless communication link127-1to the user equipment UE1.

At the user equipment UE1, the generator211-2uses the frequency signal205-2as a basis to produce carrier frequency RF1-2(same RF carrier frequency as RF1-1) supplied to the receiver230-2. The receiver230-2demodulates the received communications121to produce complex base-band signals294(such as including DATA1, DATA2, etc.) communicated from the wireless station131to the user equipment UE1. Via the base-band signals294, the DFT (Discrete Fourier Transform) function276-2produces modulated downlink data289for further processing and retrieval of corresponding downlink transmitted data DATA1, DATA2, etc.

Referring again toFIG.3, in further example embodiments, as previously discussed, the generator211-2uses the frequency signal205-2as a basis to produce one or more carrier frequency signals such as RF1-2. Transmitter220-2uses the carrier frequency RF1-2as a basis in which to communicate uplink information, reference signals, etc., to the wireless station131transmitted over the uplink of the wireless communication link127-1to the communication management resource140of wireless station131for processing.

As further discussed herein, in addition to communicating data, the transmitter220-2transmits multiple reference signals such as PT-RS (Phase Tracking Reference Signal) signals, DM-RS (Demodulation Reference) signals, etc., via one or more sub-carrier frequencies in one or more different time slots. As further discussed herein, the reference signals can be spread across time (multiple time slots or resource elements) and/or frequency domains (channels).

In this example embodiment, the phase noise estimator resource238-1monitors the received pilot reference signals (such as PT-RS signals, DM-RS signals, etc.) from the transmitter220-2and produces phase noise information245-1associated with receipt of the reference signals in communications122. Note that details of such reference signals used to produce the phase noise information245-1is further discussed below inFIGS.8-12.

Referring again toFIG.3, the receiver230-1demodulates the received communications122with the carrier frequency RF1-1(same frequency as RF1-2) to produce the phase noise information245-1. In one embodiment, as previously discussed, such phase noise information245-1(produced by the phase noise estimator resource238-1monitoring reference signals from the user equipment UE1) captures information about the total phase noise error (a.k.a., common phase error PNE11+PNE21) associated with the oscillators201-1and201-2.

In further example embodiments, the phase noise information245-1is stored in registers of the coefficient generator250. Based on the generated phase noise information245-1, the coefficient generator250generates and supplies corresponding phase noise coefficients C1, C2, etc., to the phase noise predictor model260. Based on the recently generated phase noise information245-1and corresponding derived coefficients C1, C2, C3, etc., the phase noise predictor model260produces the phase adjustment information270.

In one embodiment, as its name suggests, the phase adjustment (compensation) information270includes one or more phase adjustment settings (such as the detected phase noise error PNE11+PNE21) supplied to the phase adjustor240. To provide phase noise pre-compensation at the wireless station131, the phase adjustor240provides signal adjustments to remove respective phase noise error (common phase error such as PNE11+PNE21) from the subsequent communications122transmitted by the transmitter220-2of the user equipment UE1to the wireless station131.

As further discussed below inFIG.5, embodiments herein include one or more of providing phase noise adjustments (compensation) via phase adjustor240in the frequency domain. Alternatively, note that the phase noise compensation can be achieved in a time domain (such as via modification of signal121′) rather than in the frequency domain via signal processor241.

Referring again toFIG.3, thus, in one embodiment, the communication management resource140(such as a phase noise management resource) associated with or in the first wireless station131generates phase noise information245-1via monitoring of the received wireless communications122. The generated phase noise information245-1provides an estimate of a combination of common phase error associated with: i) first phase noise (PNE11) associated with the oscillator201-1of the wireless station131, and ii) second phase noise (PNE21) associated with the local oscillator of the user equipment UE1. In this example embodiment, as previously discussed, the phase noise information245-1is generated by the phase noise estimator resource238-1.

Based on the received phase noise information245-1, the communication management resource140produces phase noise adjustment information270. Via the phase noise adjustment information270, the communication management resource140adjusts one or more signals associated with the wireless station131via phase adjustor240. Adjustment of the one or more signals (such as adjustment of one or more sub-carrier frequencies) results in phase noise adjustment to both a first portion of phase noise (such as phase noise PE11) associated with the first wireless station131and a portion of second phase noise (such as phase noise PE21) associated with the second wireless station UE1.

Accordingly, embodiments herein include a method for estimating common phase error at the receiver (user equipment or wireless base station), in which the receiver exploits the separation between reference signals in frequency and/or time domains. If separation between adjacent CSI-RSs is larger than the extent of the ICI caused by one subcarrier, then the CSI-RSs do not cause ICI (Inter Carrier Interference) to one another, and a simple averaging of established phase noise will produce an estimate of common phase error as captured by the phase adjustment information270.

In one embodiment, based on the received pilot symbols (such as reference signals PT-RS, DM-RS, etc.), the receiver averages phase noise determined over multiple CSI-RSs (received pilot signals) to estimate the mean phase noise such as common phase error associated with both. Further embodiments herein include a method for inserting reference signals, e.g., CSI-RSs. As previously discussed, appropriate spacing of the pilot these signals can be controlled in frequency and time domain. Separation of CSI-RSs, e.g. in code domain (e.g., PN), can be implemented in order to ‘extract’ only reference signals. This will eliminate or greatly reduce phase noise-induced ICI.

FIG.4is an example block diagram illustrating components of a wireless system and implementation of a first phase noise estimator in a first wireless station and a second phase noise estimator in a second wireless station according to embodiments herein.

In this example embodiment, in a similar manner as previously discussed, the phase noise estimator resource238-2produces the phase noise information245-2based on receipt of one or more reference signals from the wireless station131. The user equipment UE1and corresponding communication management resource141communicate the phase noise information245-2to the wireless station131in a manner as previously discussed with respect toFIG.2.

Additionally, in a manner as previously discussed inFIG.3, the wireless station131implements phase noise estimator resource238-1to monitor reference signals (pilot signals) received from the user equipment UE1to produce phase noise information245-1. The coefficient generator250uses a combination of the phase noise information245-1and the phase noise information245-2(such as average of such information) to produce the respective coefficients C1, C2, etc., associated with the phase noise predictor model260.

Thus,FIG.4illustrates implementing functionality fromFIG.2and functionality fromFIG.3. In one embodiment, the phase noise predictor model260or other suitable entity produces the phase adjustment information270based on a combination of the phase noise information245-1(generated by the wireless station131) and the phase noise information245-2(generated by the user equipment UE1).

FIG.5is an example diagram illustrating implementation of phase noise adjustments in the frequency domain according to embodiments herein.

In this embodiment, the phase adjustor240provides phase noise compensation to or associated with each of multiple sub-carrier frequencies SCF1, SCF2, . . . , SCF12. For example, the phase adjustor240applies phase adjustment information270to each of the sub-carrier frequencies SCF1, SCF2, etc. Application of the complex phase adjustment information270to the sub-carrier frequency SCF1results in phase noise compensated sub-carrier frequency SCF1′; application of the complex phase adjustment information270to the sub-carrier frequency SCF2results in phase noise compensated sub-carrier frequency SCF2′; application of the complex phase adjustment information270to the sub-carrier frequency SCF3results in phase noise compensated sub-carrier frequency SCF3′; and so on. Thus, application of the phase adjustment information270to the sub-carrier frequencies provides phase noise compensation with respect to phase noise error (PNE11and PNE21).

In one embodiment, because the magnitude of the phase noise error changes over time, the value of the phase adjustment information270is constantly updated such that the phase adjustment information270more closely tracks the phase noise error.

FIG.6is an example diagram illustrating allocation of a resource block group to a wireless station according to embodiments herein. Additional details of allocated resource blocks for uplink and downlink communications is further discussed below.

FIG.7is an example flowchart diagram illustrating implementation of phase noise compensation according to embodiments herein.

In this example embodiment, in processing operation710, the user equipment UE1performs transmission of pilot signals such as PT-RS (Phase Tracking Reference Signal) signals, DM-RS (Demodulation Reference) signals, etc., to the wireless station131in one or more assigned time slots, physical resource blocks, etc.

In processing operation720, the phase noise predictor model260generates a common phase error estimate (such as phase adjustment information270) for a most recent one or more time slots of received communications122(and reference signals) from the user equipment UE1.

In processing operation730, the wireless station131generates a phase adjustment information270from the estimated common phase error and performs common phase error pre-compensation on the downlink communications121in one or more subsequent time slots.

In processing operation740, if a new uplink communication is received at the wireless station131, the phase noise estimator resource238-1produces updated phase noise information245-1for use by the phase noise predictor model260to produce the phase adjustment information270(one or more signals such as common phase error) sued to adjust subsequent communications121. In this manner, the common phase error estimation is constantly updated to be as accurate as possible. Alternatively, if no new uplink communication is received at the wireless station131in paging occasion740, the phase noise estimator resource238-1and phase noise predictor model260use the previously received phase noise information245-1to produce the phase adjustment information270(one or more signals such as common phase error).

FIG.8is an example diagram illustrating a physical resource block and allocation of corresponding resource elements according to embodiments herein.

In this example embodiment, the physical resource block801includes multiple resource elements, each of which supports conveyance of a respective symbol. In the time domain, the physical resource block801falls within a time slot between time0and1; the time slot #1includes 14 sub-time slots, one for each symbol. In the time domain, the physical resource block801resides in bandwidth BW #1, including multiple sub-carrier frequencies in the base-band such as BW1-CH #1(a.k.a., SCF1), BW1-CH #2(a.k.a., SCF2), BW1-CH #3(a.k.a., SCF3), . . . , BW1-CH #12(a.k.a., SCF12). In one nonlimiting example embodiment, each sub-carrier frequency is spaced by 15 KHz; bandwidth BW1therefore represents 180 KHz. In a manner as previously discussed, embodiments herein include providing compensation with respect to each of the sub-carrier frequencies when transmitting in a downlink direction from the wireless station131to the user equipment UE1.

In this embodiment, pilot or reference symbols are scheduled for transmission from the first wireless station to as always second wireless station in one or more of the resource elements850of the physical resource block801. The pilot or reference symbols can be any suitable signals that serve phase tacking.

In one embodiment, the physical resource block801defines a schedule of communicating PT-RS and/or DM-RS signals that serve to assist phase tracking. For example, in one embodiment, the resource elements in the physical resource block801marked with an X represent scheduling of DM-RS signals; the resource elements in the physical resource block801marked with an O represent scheduling of PT-RS signals. Other resource elements850of the physical resource block801are used to communicate other data (such as DATA1, DATA2, etc.) between the wireless stations.

As further discussed below, each physical resource block can be assigned to support uplink or downlink communications.

FIG.9is an example diagram illustrating a physical resource block and allocation of corresponding resource elements according to embodiments herein.

In this example embodiment, the physical resource block802includes multiple resource elements, each of which supports conveyance of a respective symbol. In the time domain, the physical resource block802falls within a time slot between time0and1; the time slot #1includes 14 sub-time slots, one for each symbol. In the time domain, the physical resource block802resides in bandwidth BW #2, including multiple sub-carrier frequencies BW2-CH #1, BW2-CH #2, BW2-CH #3, . . . , BW2-CH #12. In one nonlimiting example embodiment, each sub-carrier frequency in the base-band is spaced by 15 KHz, bandwidth BW2represents 180 KHz.

In this embodiment, pilot or reference symbols are scheduled for transmission in one or more of the resource elements851of the physical resource block802. The pilot or reference symbols can be any suitable signals that serve phase noise tracking. In further example embodiments, the physical resource block802defines a schedule of DM-RS signals that serve to assist phase tracking. For example, in one embodiment, the resource elements in the physical resource block802marked with an X represent scheduling of DM-RS signals.

Other resource elements851of the physical resource block802are used to communicate other data between the wireless stations.

As further discussed below, each physical resource block can be assigned to support uplink or downlink communications.

FIG.10is an example diagram illustrating implementation of multiple physical resource blocks and allocation of corresponding resource elements in the time domain and frequency domain to support downlink and uplink communications according to embodiments herein.

As previously discussed, bandwidth BW1represents a first set of sub-carrier frequencies in which the communication management resource140applies compensation in a respective downlink in a manner as previously discussed; bandwidth BW2represents a first set of sub-carrier frequencies in which the communication management resource140applies compensation in a respective downlink in a manner as previously discussed; bandwidth BW3represents a first set of sub-carrier frequencies in which the communication management resource140applies compensation in a respective downlink in a manner as previously discussed; and so on.

In this example embodiment, the wireless station131or other suitable entity allocates use of the available wireless bandwidth for uplink and downlink communications. For example, in one embodiment, the resource blocks801,802,803, . . . , resource blocks811,812,813, . . . , are allocated to support downlink communications from the wireless station131to the user equipment UE1.

Certain resource blocks are flexible and can be allocated for uplink or downlink depending on the network conditions.

In one embodiment, in a manner as previously discussed, the resource elements in the physical resource blocks marked with an X represent scheduling of DM-RS signals; the resource elements in the physical resource block802marked with an O represent scheduling of PT-RS signals. Other resource elements851of the physical resource block802are used to communicate other data between the wireless stations.

Thus, in this example embodiment, multiple physical resource block are scheduled for data transmission with PT-RS density configured as (i) transmission in every other physical resource block (801,811,821, . . . ,871,881, etc.,803,813,823, . . . ,873,883, etc., as in the frequency domain, and (ii) every other OFDM symbol in the time domain.

Note that the DM-RS signal can be used for phase tracking in lieu of PT-RS since the PT-RS port is associated with a DM-RS antenna port (precoder is common but power may be different).

For PDSCH (Physical Downlink Shared CHANNEL), the subcarrier location (configurable by RRC or Radio Resource Control) of a PT-RS in a scheduled PRB is the same as one of the subcarriers used by the DM-RS of the lowest port number among the DM-RS ports used by the scheduled PDSCH.

PUSCH with CP-OFDM uses same design and procedures for PT-RS (albeit, default PT-RS is included with QPSK or Quadrature Phase Shift Keying, too).

A motivation for not transmitting PT-RS signals in one or more resource elements, if PT-RS time density is lower than every other OFDM symbol, is to reuse the CPE (derived from an OFDM symbol that contains a PT-RS) in one (or up to three) subsequent OFDM symbol(s).

In the example embodiment as discussed herein, phase noise prediction as discussed herein at the wireless station131(such as gNb or gNode B) supplies a common phase error prediction value and applies pre-compensation for each OFDM symbol communicated in the downlink.

FIG.11is an example diagram illustrating allocation of uplink and downlink resources according to embodiments herein.

In this example embodiment, the IE TDD-UL-DL-Config is used to determine allocation of the Uplink/Downlink TDD (Time-Division Duplex) configuration used to communicate data from the wireless station131to the user equipment UE1and vice versa. Both, UE- and cell-specific IEs exist—in one embodiment, assume former in the sequel.

In further example embodiments, the tdd-UL-DL-ConfigurationCommon provides (aside from a reference SCS configuration μref), a pattern1and optionally a pattern2.

If pattern2is present then the user equipment UE1can be configured for two slot formats at a time, as shown inFIG.11.

There are a number of full downlink slots, a number of first OFDM symbols at the beginning of the slot following the last full downlink slot, a number of consecutive full uplink slots at the end of each DL-UL pattern, and a number of consecutive uplink symbols in the end of the slot preceding the first full uplink slot. Remaining OFDM symbols are flexible symbols.

A straightforward exemplary embodiment as discussed herein may include the following operations:1—Configure the wireless station131and the user equipment UE1to communicate in accordance with pattern1and a pattern22—Use the uplink transmissions (such as between T15and T21) at the end of pattern1to train the autoregressive (AR) model of the predictor at the wireless station1313—Implement coefficients as previously discussed to generate the phase adjustment information2704—Akaike criterion may indicate an order no larger than 20; 10 is typical for a spectrum with one spike (cf. PN spectrum)5—Use the AR predictor model to predict CPE in the OFDM symbols at the beginning of pattern2and communicating from the wireless station131to the user equipment UE1

In some embodiments prediction might be single step or multi-step (see current art)6—Re-train the AR model (such as ppm260) during the uplink transmissions at the end of pattern27—Go to operation5and continue, if the UE1has further contiguous scheduling

Accordingly, with reference toFIG.11, in one embodiment, between T11and T14, the wireless station131allocates downlink resources (such as one or more physical resource blocks) as previously discussed to support communications from the wireless station131to the user equipment UE1. The downstream communications include one or more pilot symbols communicated to the user equipment UE11as well as data. In one embodiment, the user equipment UE11monitors phase noise and produces respective phase noise information based on the downlink communications. The wireless station131receives the phase noise information and provides pre-compensation in respective downlink slots such as between T21and T24.

It is noted that the phase noise information and respective phase noise error changes over time. The immediate use of the phase noise information to update any phase noise error associated with downstream (downlink) communications ensures that the phase noise error correction is fairly up to date.

FIG.12is an example block diagram of a computer system for implementing any of the operations as previously discussed according to embodiments herein.

Any of the resources (such as wireless station131, user equipment UE1, communication management resource140, communication management resource141, coefficient generator250, phase noise predictor model260, phase adjustor240, etc.) as discussed herein can be configured to include computer processor hardware and/or corresponding executable instructions to carry out the different operations as discussed herein.

As shown, computer system1250of the present example includes interconnect1211coupling computer readable storage media1212such as a non-transitory type of media (which can be any suitable type of hardware storage medium in which digital information can be stored and or retrieved), a processor1213(computer processor hardware), I/O interface1214, and a communications interface1217.

Computer readable storage medium1212can be any hardware storage device such as memory, optical storage, hard drive, floppy disk, etc. In one embodiment, the computer readable storage medium1212stores instructions and/or data.

As shown, computer readable storage media1212can be encoded with communication management application140-1(e.g., including instructions) in a respective wireless station to carry out any of the operations as discussed herein.

During operation of one embodiment, processor1213accesses computer readable storage media1212via the use of interconnect1211in order to launch, run, execute, interpret or otherwise perform the instructions in communication management application140-1stored on computer readable storage medium1212. Execution of the communication management application140-1produces communication management process1402to carry out any of the operations and/or processes as discussed herein.

In accordance with different embodiments, note that computer system may reside in any of various types of devices, including, but not limited to, a mobile computer, a personal computer system, a wireless device, a wireless access point, a base station, phone device, desktop computer, laptop, notebook, netbook computer, mainframe computer system, handheld computer, workstation, network computer, application server, storage device, a consumer electronics device such as a camera, camcorder, set top box, mobile device, video game console, handheld video game device, a peripheral device such as a switch, modem, router, set-top box, content management device, handheld remote control device, any type of computing or electronic device, etc. The computer system1250may reside at any location or can be included in any suitable resource in any network environment to implement functionality as discussed herein.

Functionality supported by the different resources will now be discussed via flowcharts inFIG.13. Note that the steps in the flowcharts below can be executed in any suitable order.

FIG.13is a flowchart1300illustrating an example method according to embodiments herein. Note that there will be some overlap with respect to concepts as discussed above.

In processing operation1310, phase noise predictor model260receives phase noise information245(as phase noise information245-1and/or phase noise information245-2). The phase noise information captures an estimate of common phase error such as: i) first phase noise (such as PE11) associated with a first wireless station131, and ii) second phase noise (such as PE21) associated with a second wireless station (user equipment UE1).

In processing operation1320, based on the received phase noise information245, the phase noise predictor model260produces a phase noise adjustment information270(phase noise compensation information associated with sub-carrier frequencies).

In processing operation1330, the phase adjustor240applies the phase noise adjustment information270to adjust a signal of the first wireless station.

Note again that techniques herein are well suited to facilitate use of a shared wireless channel amongst different types of wireless stations. However, it should be noted that embodiments herein are not limited to use in such applications and that the techniques discussed herein are well suited for other applications as well.