A network-side receiver for receiving high-speed transmission signals.

Abstract

Techniques are provided for receiving PUSCH and PUCCH transmitted by a high speed transmitter. The techniques include: calculating a phase difference of an OFDM symbol of PUCCH from an OFDM symbol of a first DM-RS and an OFDM symbol of a second DM-RS of PUCCH; and correlating the OFDM symbols of the first DM-RS and the second DM-RS. Determine a Doppler shift and report it to L2. Compensate the channel estimate and data symbols with the Doppler shift. Equalize and demodulate the PUCCH. Perform a first level of phase correction on the PUSCH by correcting the phase of the output samples of the IDFT from the Doppler shift received from L2. Measure a phase deviation for the output of the first level of phase correction, accumulate the measured phase deviation and the Doppler shift received from L2 to derive an accumulated phase correction, and report the accumulated phase correction to L2. Demodulate the PUSCH.

Description

[Technical field]

[0001] In one exemplary embodiment, the subject matter herein relates generally to mobile wireless communication systems, and more particularly to a network side receiver that receives wireless signals transmitted from mobile type devices moving at high speeds. [Background technology]

[0002] The introduction and proliferation of digital wireless networks in the 1990s marked the beginning of the wireless revolution. Commercial wireless providers migrated from analog wireless technologies to digital wireless technologies that allowed more efficient use of radio resources, which led to an increase in wireless voice traffic and a dramatic increase in wireless digital data services. What followed was a paradigm shift from wired to wireless. Wireless computer networks, wireless Internet, etc. are now expected to be available almost ubiquitously.

[0003] Wireless users can include traditional mobile phone users and users of portable computing devices such as laptop computers or tablets. It is becoming difficult to distinguish the difference between modern mobile phones and personal computing devices. Modern mobile phones are transforming into personal computing devices that host applications or services for calling, texting, messaging, email, video recording and viewing, and live streaming, as well as applications typically found on personal or business computing devices, e.g., word processing, spreadsheets, etc.

[0004] Wireless access is available in virtually every urban area, and it is becoming commonplace for wireless users to access their devices while traveling in cars, buses, trains, etc.

[0005] To establish and maintain a wireless connection between a wireless device and a wireless network receiver, such as a base station or eNB, the base station or eNB must be able to decode the Physical Uplink Shared Channel (PUSCH) and the Physical Uplink Control Channel (PUCCH).

[0006] Some land transportation modes offer high speed or fast travel, such as bullet trains which can travel at speeds in excess of 350 kph or 217 mph.

[0007] Conventional wireless network receivers (e.g., eNBs) may not be able to decode the PUSCH and PUCCH due to the high phase deviation caused by the Doppler shift in the transmitted signals in a high-velocity environment. In some transportation modes, WiFi services are available, but access is limited.

[0008] Therefore, a solution is needed to enable a network receiver, such as a base station or eNB, to receive transmitted signals while moving at high velocity, i.e., fast speed. Summary of the Invention

[0009] In one general aspect, a method is disclosed for decoding a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH) transmitted in a high velocity environment and received by a receiver. The method may include calculating a phase difference of an orthogonal frequency division multiplexing (OFDM) symbol of a first demodulation reference signal (DM-RS) of the PUCCH from an OFDM symbol of a second DM-RS of the PUCCH received by the receiver. The method may include correlating OFDM symbols of the first DM-RS and the second DM-RS and determining a Doppler shift proportional to the phase difference between the DM-RS symbols in the channel. The method may include reporting the Doppler shift to Layer 2 (L2) of a protocol stack. The method may include compensating a channel estimate and data symbols with the Doppler shift and equalizing and demodulating the PUCCH. The method may include performing a first level of phase correction on the PUSCH received by the receiver by correcting a phase on an output sample of an Inverse Discrete Fourier Transform (IDFT) from the Doppler shift received from Layer 2, measuring a phase deviation on an output of the first level of phase correction, accumulating the measured phase deviation on an output of the first level of phase correction and the Doppler shift received from Layer 2 to derive an accumulated phase correction, and reporting the accumulated phase correction to Layer 2. The method may include performing a second level of phase correction according to the measured phase deviation of an output of the first level of phase correction, and demodulating the PUSCH. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform operations of the method.

[0010] In another general aspect, an apparatus is disclosed for decoding a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH) transmitted in a high velocity environment and received by a receiver. The apparatus may include a memory configured to store a plurality of instructions, and a processor circuit coupled to the memory. The processor circuit is configured to execute the plurality of instructions to: calculate a phase difference of an orthogonal frequency division multiplexing (OFDM) symbol of a first demodulation reference signal (DM-RS) of the PUCCH and an OFDM symbol of a second DM-RS of the PUCCH received by the receiver; correlate the OFDM symbols of the first DM-RS and the second DM-RS; determine a Doppler shift proportional to the phase difference between the DM-RS symbols in the channel; report the Doppler shift to Layer 2 of a protocol stack; compensate channel estimates and data symbols with the Doppler shift; and decode the PUCCH. and performing a first level of phase correction on the PUSCH received by the receiver by equalizing and demodulating, and correcting a phase on an output sample of an inverse discrete Fourier transform (IDFT) from the Doppler shift received from layer 2, measuring a phase deviation on an output of the first level phase correction, accumulating the measured phase deviation and the Doppler shift received from layer 2 on an output of the first level phase correction to derive an accumulated phase correction, reporting the accumulated phase correction to layer 2, performing a second level of phase correction according to the measured phase deviation of the output of the first level phase correction, and demodulating the PUSCH.

[0011] In yet another general aspect, a communication system is disclosed that includes a mobile device configured to transmit a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH) in a high-velocity environment, and an eNB configured to receive the PUSCH and the PUCCH. The eNB calculates a phase difference of an orthogonal frequency division multiplexing (OFDM) symbol of a first demodulation reference signal (DM-RS) of the PUCCH and an OFDM symbol of a second DM-RS of the PUCCH received from the mobile device, correlates the OFDM symbols of the first DM-RS and the second DM-RS, determines a Doppler shift proportional to the phase difference between the DM-RS symbols in the channel, reports the Doppler shift to Layer 2 of a protocol stack, compensates channel estimates and data symbols with the Doppler shift, equalizes and demodulates the PUCCH, and transmits the PUSCH and the PUCCH to Layer 2. the Doppler shift received from Layer 2 to perform a first level of phase correction on the PUSCH received by the receiver by correcting a phase for an output sample of an Inverse Discrete Fourier Transform (IDFT) from the Doppler shift received from Layer 2; measuring a phase deviation for an output of the first level of phase correction; accumulating the measured phase deviation and the Doppler shift received from Layer 2 for an output of the first level of phase correction to derive an accumulated phase correction; reporting the accumulated phase correction to Layer 2; and performing a second level of phase correction according to the measured phase deviation of the output of the first level of phase correction to demodulate the PUSCH.

[0012] Implementations may include one or more of the following features: A method, apparatus, or system, where measuring a phase deviation for an output of the first level of phase correction includes moving all quadrature amplitude modulation (QAM) symbols to the first quadrant by applying a phase shift of -π / 4, -π / 2, and -π / 3 radians to symbols in the second, third, and fourth quadrants, respectively; calculating a difference between an average phase of the QAM symbols and an expected average phase of π / 4 radians or 45 degrees; A method, apparatus, or system, where performing the second level of phase correction twice if the Doppler shift received from Layer 2 has a value of 0; A method, apparatus, or system, where performing the first level of phase correction for the PUSCH includes receiving a Doppler shift reported by Layer 1 to Layer 2; A method, apparatus, or system, where the first DM-RS and the second DM-RS are 4 symbols apart, and the phase correction applied to the first and second DM-RS symbols and data symbols is the phase deviation measured on the PUCCH. Implementations of the described techniques may include hardware, a method or process, or a computer-tangible medium.

[0013] The drawings are as follows: [Brief description of the drawings]

[0014] [Figure 1] 1 illustrates a communication link between a mobile device and a network device according to an exemplary embodiment.

[0015] [Diagram 2] 1 illustrates a generalized PUSCH receive chain.

[0016] [Diagram 3] 1 illustrates a generalized PUCCH receive chain.

[0017] [Figure 4]FIG. 1 shows a Quadrature Phase Shift Keying (QPSK) constellation diagram.

[0018] [Diagram 5] FIG. 1 shows a 16QAM constellation diagram.

[0019] [Figure 6] FIG. 2 illustrates a PUCCH receiver processing chain according to an embodiment.

[0020] [Figure 7] 1 illustrates a PUSCH receiver processing chain according to an embodiment.

[0021] [Figure 8] 1 is a flow chart of an example process for receiving a PUCCH transmitted from a high velocity mobile device.

[0022] [Figure 9] 1 is a flow chart of an example process for receiving a PUSCH transmitted from a high velocity mobile device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] 1 is a diagram illustrating a communication link between a mobile device and a network device. The network device 102, which may be a base station (eNB) or an access point, transmits signals 106 to the mobile device 104 and receives signals 108 transmitted by the mobile device 104. The signals 106 may be referred to as downlink (DL) signals, and the signals 108 may be referred to as uplink (UL) signals. The mobile device 104 receives signals 106 from the network device 102 and transmits signals 108 to the network device 102.

[0024] In wireless communication systems such as LTE, there are significant differences between UL and DL signals. These differences include transmission and multiple access schemes, which may result in different physical layer processing. For example, UL may be based on Single Carrier Frequency Division Multiple Access (SC-FDMA) and DL may be based on Orthogonal Frequency Division Multiple Access (OFDMA). SC-FDMA modulation may have a lower peak-to-average power ratio, which may result in lower cost amplifiers and less power usage. User data is modulated into a single carrier modulation format and may be modulated using higher order modulation such as Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (QAM), or 64QAM. In 16QAM, the carrier may be modulated into any of 16 different phase and amplitude states, and in 64QAM, the carrier may be modulated into any of 64 different phase and amplitude states.

[0025] The uplink signal may not have a dedicated synchronization signal. The uplink frame may be synchronized using the PUCCH demodulation reference signal (DM-RS). The following description focuses on the PUSCH and PUCCH. The PUSCH carries user data and control signal data. The control data information may be multiplexed with the user data before the Discrete Fourier Transform (DFT) spreading module in the uplink SC-FDMA physical layer.

[0026] 2 illustrates a generalized PUSCH receive chain. At 204, a PUSCH signal is received 202. At 204, the signal is equalized and an Inverse Discrete Fourier Transform (IDFT) is performed. At 206, the PUSCH signal 202 is demodulated.

[0027] Figure 3 illustrates a generalized PUCCH receive chain. A PUCCH signal 302 is received at 304. Channel estimation is performed on the DM-RS symbols of the PUCCH at 304. Channel equalization is performed at 306, and the PUCCH is demodulated at 308. The PUSCH receive chain illustrated in Figure 2 and the PUCCH receive chain illustrated in Figure 3 are examples of receive chains that may not be able to decode PUSCH and PUCCH transmitted by a transmitter moving at high speed.

[0028] FIG. 4 shows a QPSK constellation diagram. In the modulation technique used for digital communication, the variation applied to the carriers is limited according to the discrete information being transmitted. The original signal is separated into a set of independent components I and Q. The data is separated into two channels, I and Q. Two bits are transmitted simultaneously, one bit per channel. The two carriers are transmitted in combination. The I and Q components are separated by 90° and may be considered to be orthogonal or quadrature. When viewed as a polar representation, the magnitude and phase are represented together, as illustrated at 402. It is noted that the modulation of the PUCCH is generally QPSK.

[0029] In the case of QPSK modulation, the carrier may vary in terms of phase, as opposed to frequency variation. QPSK signals shift between discrete phase states that are 90° apart. Thus, a QPSK symbol may be represented by four discrete values. By way of example, discrete values ​​00, 01, 10, and 11 are shown in 402. In the QPSK modulation shown in 402, 11 may represent a discrete value of 45°, 01 may represent a discrete value of 135°, 00 may represent a discrete value of 225°, and 10 may represent a discrete value of 315°, with each discrete value having a carrier amplitude of 1.0.

[0030] The QPSK constellation diagram at 404 illustrates equalized QPSK signals centered around their corresponding discrete values, which illustrates a QPSK constellation without significant Doppler shift.

[0031] A tilted QPSK constellation diagram is shown at 406. A tilted QPSK constellation diagram may result from a Doppler shift where the tilt increases as the Doppler shift increases. The Doppler shift appears as a phase ramp across the OFDM symbols. This may be viewed as an angular deviation of the decoded symbols. OFDM symbols immediately adjacent to the DM-RS may not exhibit much tilt, while symbols further away from the DM-RS may have a large tilt that cannot be compensated for. Thus, signals transmitted from devices moving at high speeds may be difficult or impossible for a conventional network receiver to decode due to the high phase deviation caused by Doppler spread.

[0032] Although FIG. 4 illustrates a QPSK constellation, it should be understood that the Doppler shift described above may be similar in a QAM signal, for example, a 16-QAM signal. For QAM modulation, the discrete values ​​correspond to phase and amplitude states. The QAM constellation diagram may be the same as the QPSK constellation diagram, with discrete values ​​of 45 degrees, 135 degrees, 225 degrees, and 315 degrees.

[0033] FIG. 5 shows a 16-QAM constellation diagram. In a 16-QAM modulated signal, a continuous bit stream is represented as a sequence and may be divided into four groups in each of four quadrants. In the 16-QAM constellation diagram 502, it can be seen that each quadrant contains four groups. In 16-QAM, six bits are used to represent phase and amplitude states; that is, four I values ​​and four Q values ​​are used, yielding four bits per symbol (2 4=16). Thus, the amplitude and phase of the radio signal can be adjusted to one of 16 different discrete and measurable states, as shown at 502.

[0034] It should be appreciated that a tilted QAM constellation may resemble the tilted QPSK diagram shown at 406 resulting from a Doppler shift, where the tilt increases as the Doppler shift increases.

[0035] Note that the PUCCH does not use the DFT SC-FDMA precoding used for the PUSCH data symbols, and as mentioned above, the modulation for the PUCCH is typically QPSK.

[0036] 6 is a diagram illustrating a PUCCH receiver processing chain according to an embodiment. The highlighted portion represents new processing that can be implemented to solve the problem of receiving a PUCCH signal transmitted by a transmitter moving at a fast speed.

[0037] PUCCH channel estimation for DM-RS is performed at 602. DM-RS is a reference signal for PUCCH. Format 1x and Format 2x of PUCCH have multiple OFDM symbols carrying pilot signals.

[0038] PUCCH format 1x typically has three DM-RS symbols located in the center of the PUCCH slot. PUCCH format 2x typically has two DM-RS symbols, which are typically located in the second and penultimate symbols of the PUCCH slot. Thus, there are differences in the processing between PUCCH format 1x and PUCCH format 2x. The following description is directed to PUCCH format 2x.

[0039] For PUCCH format 2x, the phase difference between the OFDM symbols of the first DM-RS and the OFDM symbols of the second DM-RS is calculated. The OFDM symbols of the first DM-RS and the second DM-RS are correlated and a Doppler shift is determined. The Doppler shift is proportional to the phase difference between the DM-RS symbols in the channel. The Doppler shift is reported to L2 as a phase deviation at 606.

[0040] At 608, phase correction is performed on the DM-RS and data symbols of the PUCCH, i.e., at 608, the phase of the DM-RS and data symbols are compensated using the estimated phase deviation performed at 604. At 610, equalization of the PUCCH is performed on the output of 608.

[0041] A PUCCH channel estimation is performed using the DM-RS symbols at 602. For a PUCCH transmitted by a transmitter moving at a fast speed, the phase deviation resulting from high Doppler shift is estimated at 604. The phase deviation estimated at 604 is reported to L2 at 606.

[0042] 7 is a diagram illustrating a PUSCH receiver processing chain according to an embodiment, the highlighted portion represents new processing that may be implemented to solve the problem of receiving a PUSCH signal transmitted by a transmitter moving at a fast speed.

[0043] At 702, the received PUSCH is equalized and an Inverse Discrete Fourier Transform (IDFT) is performed. At 704, Doppler shift information is received from Layer 2. The Doppler shift is proportional to the phase deviation. At 706, a first level of phase correction is performed on the output samples of the IDFT using the Doppler shift information received from L2. That is, the phase of the IDFT output samples may be corrected according to the Doppler shift information received from L2 at 704, where the Doppler shift appears as a phase spread between OFDM symbols.

[0044] The phase deviation for the output of the first level phase correction 706 is measured at 708. The phase deviation may be measured by moving all QAM symbols to the first quadrant by applying a phase shift of -π / 4, -π / 2, -π / 3 radians to the symbols in the second, third, and fourth quadrants, respectively. Measuring the phase deviation may include calculating the difference between the expected average phase of π / 4 radians or 45 degrees.

[0045] Accumulating the measured phase deviation against the output of the first level phase correction in 706 and the Doppler shift received from Layer 2 in 704 is performed to derive an accumulated phase correction in 710. The accumulated phase correction is reported to L2 in 712. This can be seen as a kind of feedback whereby the measured phase deviation in 708 is refined or improved. As a generalized example, considering the Doppler shift in 704 as corresponding to a value of 45°, or its equivalent in radians, and as a result of measuring the phase deviation in 708, it is determined that there is another 5° of phase correction. The 45° is accumulated with 5° in 710 and 50° is reported to L2. The process in 706 to 710 may be repeated such that the phase deviation reported in 712 is refined with each iteration.

[0046] At 714, a second level of phase correction is performed on the output of 710. The phase is corrected at 714 based on the output of the first level of phase correction at 706 and the measured and accumulated phase corrections at 708-710. At 716, the PUSCH is demodulated.

[0047] The Doppler shift information received from L2 at 704 may correspond to the phase deviation estimated and reported from the PUCCH (see 604 and 608 in FIG. 6). It may be that the PUCCH has not yet been received and the reported PUCCH phase deviation is old or out of date and no longer valid. In such a case, the Doppler shift information received from L2 at 704 may be reported as a zero (0) value.

[0048] If the Doppler shift received from L2 is zero, then the process at 714 may be performed twice.

[0049] It should be appreciated that the PUCCH processing at 604, 606, and 608, and the PUSCH processing at 704 and 706-714 provide a solution to the problem that conventional network receivers are unable to decode the PUCCH and / or PUSCH transmitted by a transmitter moving at a fast speed. These processes determine the phase deviation caused by the high Doppler spread of the high speed transmitter and compensate for the phase deviation before demodulating the PUCCH and / or PUSCH.

[0050] FIG. 8 is a flow chart of an example process for receiving a PUCCH transmitted from a high velocity mobile device.

[0051] As shown in FIG. 8, process 800 may include, at 802, calculating a phase difference of an OFDM symbol of a PUCCH from an OFDM symbol of a first DM-RS of a PUCCH and an OFDM symbol of a second DM-RS of a PUCCH received by a network receiver. For example, as described above, the receiver may calculate a phase difference of an ODMA symbol of a PUCCH from an OFDM symbol of a first DM-RS of a PUCCH and an OFDM symbol of a second DM-RS of a PUCCH. Process 800 may include, at 804, correlating the OFDM symbols of the first DM-RS and the second DM-RS. For example, as described above, the receiver or device may correlate the OFDM symbols of the first DM-RS and the second DM-RS. Process 800 may include, at 806, determining a Doppler shift proportional to the phase difference between the DM-RS symbols in the channel. For example, the receiver or device may determine a Doppler shift proportional to a phase difference between DM-RS symbols in the channel, as described above, and the process 800 may include reporting the Doppler shift to layer 2 (L2) of a protocol stack, at 808. For example, the receiver or device may report the Doppler shift to L2 of the protocol stack, as described above. As further shown in FIG. 8, the process 800 may compensate the channel estimate and data symbols with the Doppler shift, at 810. For example, the receiver or device may compensate the channel estimate and data symbols with the Doppler shift, as described above. As also shown in FIG. 8, the process 800 may include equalizing and demodulating the PUCCH, at 812. For example, the receiver or device may equalize and demodulate the PUCCH, as described above.

[0052] Although Figure 8 illustrates example blocks of process 800, in some implementations, process 800 may include blocks in addition to, fewer than, different than, or arranged differently than those depicted in Figure 8. Additionally or alternatively, two or more of the blocks of process 800 may be performed in parallel.

[0053] Process 800 may include additional implementations, such as any single implementation or any combination of implementations described below, and / or in conjunction with one or more other processes described elsewhere herein.

[0054] FIG. 9 is a flow chart of an example process for receiving a PUSCH transmitted from a high velocity mobile device.

[0055] The process 900 may include, at 902, performing a first level of phase correction on the received PUSCH by correcting a phase of an output sample of the IDFT from a Doppler shift received from L2. For example, the receiver of the device may perform the first level of phase correction on the PUSCH received by the receiver by correcting a phase on an output sample of the IDFT from a Doppler shift received from L2, as described above. As also shown in FIG. 9, the process 900 may include, at 904, measuring a phase deviation for an output of the first level of phase correction. For example, the receiver of the device may measure a phase deviation for an output of the first level of phase correction, as described above. As further shown in FIG. 9, the process 900 may include, at 906, accumulating the measured phase deviation for the output of the first level of phase correction and the Doppler shift received from L2 to derive an accumulated phase correction. For example, the receiver or device may accumulate the first level of phase correction with the measured phase deviation to derive an accumulated phase correction, as described above. Process 900 may include reporting the accumulated phase correction to L2, at 908. For example, the receiver of the device may report the accumulated phase correction to L2, as described above.

[0056] 9, the process 900 may include, at 910, performing a second level of phase correction according to the measured phase deviation of the output of the first level of phase correction. For example, the receiver or device may perform the second level of phase correction according to the measured phase deviation of the output of the first level of phase correction, as described above. The process 900 may include, at 912, demodulating the PUSCH. For example, the receiver or device may demodulate the PUSCH, as described above.

[0057] Although Figure 9 illustrates example blocks of process 900, in some implementations, process 900 may include blocks in addition to, fewer than, different than, or arranged differently than those depicted in Figure 9. Additionally or alternatively, two or more of the blocks of process 900 may be performed in parallel.

[0058] Process 900 may include additional implementations, such as any single implementation or any combination of implementations described below, and / or in conjunction with one or more other processes described elsewhere herein.

[0059] In a first implementation, measuring the phase deviation relative to the output of the first level of phase correction includes moving all quadrature amplitude modulation (QAM) symbols to the first quadrant by applying phase shifts of -π / 4, -π / 2, and -π / 3 radians to symbols in the second, third, and fourth quadrants, respectively.

[0060] In a second implementation, alone or in combination with the first implementation, the process 800 may include calculating the difference between the average phase of the QAM symbols and an expected average phase of π / 4 radians or 45 degrees.

[0061] In a third implementation, alone or in combination with the first and second implementations, the measured phase deviation of the output of the first level phase correction in the PUSCH is reported to Layer 2 as an input for the first level phase correction if the Doppler shift of the PUCCH has a value of 0.

[0062] In a fourth implementation, alone or in combination with one or more of the first to third implementations, performing a first level of phase correction on the PUSCH includes receiving a Doppler shift reported to Layer 2 by the PUCCH.

[0063] In a fifth implementation, alone or in combination with one or more of the first to fourth implementations, the first DM-RS and the second DM-RS are four symbols apart.

[0064] In a sixth implementation, alone or in combination with one or more of the first to fifth implementations, the phase correction applied to the first and second DM-RS symbols and data symbols is a phase deviation measured over a Transmission Time Interval (TTI) for the first and second DM-RS symbols.

[0065] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the recited features, through a study of the drawings, the disclosure, and the appended claims.

[0066] In the claims, the word "comprising" does not exclude other elements or steps and the indefinite article "a" or "an" does not exclude a plurality.

[0067] A single processor, device or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0068] Operations such as obtaining, accessing, analyzing, capturing, comparing, determining, inputting, obtaining, outputting, providing, storing or saving, calculating, simulating, receiving, alerting, and stopping may be implemented as program code means of a computer program and / or as dedicated hardware.

[0069] The computer program may be stored and / or distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

Claims

1. 1. A method for decoding a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH) transmitted in a high-velocity environment and received by a receiver, comprising: Calculating a phase difference of an orthogonal frequency division multiplexing (OFDM) symbol of the PUCCH from an OFDM symbol of a first demodulation reference signal (DM-RS) of the PUCCH and an OFDM symbol of a second DM-RS of the PUCCH received by the receiver; correlating OFDM symbols of the first DM-RS and the second DM-RS; determining a Doppler shift proportional to the phase difference between the DM-RS symbols in the channel; reporting the Doppler shift to layer 2 of a protocol stack; compensating the channel estimates and data symbols using the Doppler shift; equalizing and demodulating the PUCCH; performing a first level of phase correction on the PUSCH received by the receiver by correcting the phase on output samples of an Inverse Discrete Fourier Transform (IDFT) from the Doppler shift received from Layer 2; measuring a phase deviation relative to an output of the first level of phase correction; accumulating the measured phase deviation and the Doppler shift received from Layer 2 against the output of the first level phase correction to derive an accumulated phase correction; reporting the accumulated phase correction to Layer 2; and performing a second level of phase correction according to the measured phase deviation of an output of the first level of phase correction; and demodulating the PUSCH.

2. 2. The method of claim 1, wherein measuring the phase deviation relative to the output of the first level of phase correction comprises moving all quadrature amplitude modulation (QAM) symbols into a first quadrant by applying phase shifts of −π / 4, −π / 2, and −π / 3 radians to symbols in second, third, and fourth quadrants, respectively.

3. 3. The method of claim 2, further comprising calculating a difference between the average phase of the QAM symbols and an expected average phase of π / 4 radians or 45 degrees.

4. 2. The method of claim 1, wherein performing the first level of phase correction on the PUSCH includes receiving by Layer 1 the Doppler shift reported to Layer 2.

5. The method of claim 4 , further comprising: performing the second level of phase correction twice if the Doppler shift received from layer 2 has a value of zero.

6. The method of claim 1 , wherein the first DM-RS and the second DM-RS are four symbols apart.

7. The method of claim 1 , wherein the phase correction applied to the first and second DM-RS symbols and the data symbols is a phase deviation measured on the PUCCH.

8. 1. An apparatus for decoding a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH) transmitted in a high-velocity environment and received by a receiver, comprising: Calculating a phase difference between an orthogonal frequency division multiplexing (OFDM) symbol of the PUCCH from an OFDM symbol of a first demodulation reference signal (DM-RS) of the PUCCH received by the receiver and an OFDM symbol of a second DM-RS of the PUCCH; correlating OFDM symbols of the first DM-RS and the second DM-RS; determining a Doppler shift proportional to the phase difference between the DM-RS symbols in the channel; reporting the Doppler shift to layer 2 of a protocol stack; using the Doppler shift to compensate the channel estimates and data symbols; Equalizing and demodulating the PUCCH; performing a first level of phase correction on the PUSCH received by the receiver by correcting the phase on output samples of an Inverse Discrete Fourier Transform (IDFT) from the Doppler shift received from Layer 2; measuring a phase deviation relative to the output of the first level of phase correction; accumulating the measured phase deviation and the Doppler shift received from Layer 2 against the output of the first level phase correction to derive an accumulated phase correction; reporting the accumulated phase correction to Layer 2; performing a second level of phase correction according to the measured phase deviation of the output of the first level of phase correction; An apparatus configured to demodulate the PUSCH.

9. 9. The apparatus of claim 8, wherein measuring the phase deviation relative to the output of the first level of phase correction comprises moving all quadrature amplitude modulation (QAM) symbols into a first quadrant by applying phase shifts of −π / 4, −π / 2, and −π / 3 radians to symbols in second, third, and fourth quadrants, respectively.

10. The apparatus of claim 9, further configured to calculate the difference between the average phase of the QAM symbols and an expected average phase of π / 4 radians, or 45 degrees.

11. 10. The apparatus of claim 8, wherein performing the first level of phase correction on the PUSCH includes receiving by layer 1 the Doppler shift reported to layer 2.

12. 12. The apparatus of claim 11, wherein the second level phase correction is performed twice if the Doppler shift received from Layer 2 has a value of zero.

13. The apparatus of claim 8 , wherein the first DM-RS and the second DM-RS are four symbols apart.

14. The apparatus of claim 8 , wherein the phase correction applied to the DM-RS symbols and the data symbols is a phase deviation measured among all the DM-RS symbols.

15. 1. A communication system comprising: a mobile device configured to transmit a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH) in a high-velocity environment; an eNodeB; The eNodeB, a receiver; calculating a phase difference of an orthogonal frequency division multiplexing (OFDM) symbol of the PUCCH from a first demodulation reference signal (DM-RS) OFDM symbol of the PUCCH and an OFDM symbol of a second DM-RS of the PUCCH transmitted from the mobile device and received by the receiver; correlating OFDM symbols of the first DM-RS and the second DM-RS; determining a Doppler shift proportional to the phase difference between the DM-RS symbols in the channel; reporting the Doppler shift to layer 2 of a protocol stack; using the Doppler shift to compensate the channel estimates and data symbols; Equalizing and demodulating the PUCCH; performing a first level of phase correction on the PUSCH received by the receiver by correcting the phase on output samples of an Inverse Discrete Fourier Transform (IDFT) from the Doppler shift received from Layer 2; measuring a phase deviation relative to the output of the first level of phase correction; accumulating the measured phase deviation and the Doppler shift received from Layer 2 against the output of the first level phase correction to derive an accumulated phase correction; reporting the accumulated phase correction to Layer 2; performing a second level of phase correction according to the measured phase deviation of the output of the first level of phase correction; A communication system configured to demodulate the PUSCH.

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