# US 10,122,555 B2 · Cross-phase estimation for dual polarized microwave transceiver > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,122,555 B2 - Document ID: US10122555B2 - Status: Granted - Kind: B2 - Application number: 15/075,666 - Filed: 2016-03-21 - Published: 2017-09-21 - Granted: 2018-11-06 - Earliest claimed: 2016-03-21 - Assignees: Huawei Technologies Co., Ltd. - Applicants: Huawei Technologies Co., Ltd. - Inventors: Hoda Shahmohammadian; Ahikam Aharony - Web page: https://patentgrep.com/patent/US10122555B2 ## CPC - H04L 27/02: Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation (H04L27/32 takes precedence) - H04L 5/04: the signals being represented by different amplitudes or polarities, e.g. quadriplex - H04L 25/0224: {using sounding signals} - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Cross-phase interference occurs in dual polarized or orthogonal polarized microwave links when independent local oscillators (LOs) are utilized in each outdoor unit (ODU) transceiver operating on the same frequency channel. If the cross-phase noise is not compensated the performance of the microwave link will be degraded. In order to reduce cross-phase noise two or more pilot symbols are utilized to enable cross-phase noise estimates to be determined at the receiver of the microwave link. The pilot symbols enable a cross-phase noise compensation factor to be determined for the signal from the one or more cross-phase noise estimates. The received signal can then be compensated using the estimated cross-phase noise compensation factor. ## Claims ### Claim 1 A method of cross-phase noise compensation on a microwave communication link provided by at least two independent pairs of transmitter/receiver outdoor units (ODUs), the method comprising: receiving, by a first one of the at least two independent receiver ODUs, a signal having a first polarization transmitted from a first one of the at least two independent transmitter ODUs of the microwave communication link, the received signal comprising a plurality of transmitted consecutive pilot symbols in temporal proximity to each other; and compensating, by the first one of the two independent receiver ODUs, the signal having the first polarization by estimating cross-phase noise in the plurality of transmitted pilot symbols wherein cross-phase interference is introduced from a signal having a second polarization orthogonal to the first polarization and transmitted from a second one of the at least two independent transmitter ODUs of the microwave communication link, and wherein estimating the cross-phase noise is performed by the first one of the at least two independent receiver ODUs independently from all of said receiver ODUs other than said first one of the at least two independent receiver ODUs. ### Claim 2 (depends on 1) The method of claim 1 wherein compensating the signal having the first polarization further comprises: determining one or more cross-phase noise estimates from each of the plurality of transmitted consecutive pilot symbols; determining a cross-phase compensation factor for the signal having the first polarization from the one or more cross-phase noise estimates; and compensating the signal having the first polarization using the estimated cross-phase compensation factor. ### Claim 3 (depends on 1) The method of claim 1 wherein the plurality of transmitted consecutive pilot symbols comprises two consecutive pilots. ### Claim 4 (depends on 3) The method of claim 3 wherein the plurality of consecutive pilot symbols comprises four consecutive pilots wherein six cross-phase noise estimates are determined from the four consecutive pilots. ### Claim 5 (depends on 1) The method of claim 1 wherein compensating is performed according to a formula: rH,H−ejφrH,V=sHPejθ13 where rH,H is a channel equalized received horizontally polarized signal; ejφrH,V is a cross-phase interference from a channel equalized vertically polarized signal on the horizontally polarized signal where φ is the cross-phase noise component; and sHPjθ13 is a horizontally polarized transmitted pilot signal affected with phase noise of local oscillators ejθ2 of a transmitter and ejθ3 of a receiver for the horizontally polarized signal of the microwave communication link. ### Claim 6 (depends on 1) The method of claim 1 wherein compensating is performed according to a formula: rV,V−ejφrV,H=sVPejθ24 where rV,V is a channel equalized received vertically polarized signal; ejφrV,H is a cross-phase interference from a channel equalized horizontally polarized signal on the vertically polarized signal where φ is the cross-phase noise component; and sVPejθ24 is a vertically polarized transmitted pilot signal affected with phase noise of local oscillators ejθ2 of a transmitter and ejθ4 of a receiver for the vertically polarized signal of the microwave communication link. ### Claim 7 (depends on 2) The method of claim 2 wherein determining the cross-phase compensation factor further comprises: generating channel approximation pairing for each of the transmitted plurality of consecutive pilot symbols; solving each pairing to provide the one or more cross-phase noise estimates; and determining a minimum metric from the one or more of cross-phase noise estimates. ### Claim 8 (depends on 7) The method of claim 7 wherein compensating is performed according to a formula: rH,H−ejφrH,V=sHPejθ13 where rH,H is a channel equalized received horizontally polarized signal; ejφrH,V is a cross-phase interference from a channel equalized vertically polarized signal on the horizontally polarized signal, where φ is the cross-phase noise component; and sHPejθ13 is a horizontally polarized transmitted pilot signal affected with phase noise of local oscillators ejθ2 of a transmitter and ejθ2 of a receiver for the horizontally polarized signal of the microwave communication link; wherein the noise compensation factor is determined by solving for each set of transmitted pilot symbols by: φ = angle ⁡ ( r H , H , m ⁢ s HP , n - r H , H , n ⁢ s HP , m r H , V , m ⁢ s HP , n - r H , V , n ⁢ s HP , m ) where m and n are a number of the pilot symbol between 1 to M transmitted pilot symbols. ### Claim 9 (depends on 7) The method of claim 7 wherein compensating is performed according to a formula: rV,V−ejφrV,H−sVPejθ24 where rV,V is a channel equalized received vertically polarized signal; ejφrV,H is a cross-phase interference from a channel equalized horizontally polarized signal on the vertically polarized signal where φ is the cross-phase noise component; and sVPejθ24 is a vertically polarized transmitted pilot signal affected with phase noise of local oscillators ejθ2 of a transmitter and ejθ4 of a receiver for the vertically polarized signal of the microwave communication link; wherein a cross-phase compensation factor associated with a first set of pilot symbols is interpolated with a cross-phase compensation factor associated with a second set of pilot symbols to compensate the signal having the first polarization. ### Claim 10 (depends on 1) The method of claim 1 wherein compensating the signal further comprises: determining a first compensation factor for a first set of pilot symbols; and determining a second compensation factor for a second set of pilot symbols received subsequent to the first set of pilot symbols; wherein the determined first and second compensation factors are applied to data received between the first set of pilot symbols and the second set of pilot symbols. ### Claim 11 (depends on 10) The method of claim 10 wherein cross-phase compensation of the signal is performed by obtaining a linear approximation between the first and second compensation factors and by applying the approximation to data received between the first and second sets of pilot symbols. ### Claim 12 (depends on 2) The method of claim 2 wherein the cross-phase compensation factor is determined by applying a Wiener filter approximation on the cross-phase noise estimates of pilot symbols based upon N groups of consecutive pilots. ### Claim 13 (depends on 1) The method of claim 1 wherein the phase noise between consecutive pilots does not vary significantly between consecutive symbols. ### Claim 14 An outdoor unit (ODU) of a microwave communication link provided by at least two independent pairs of transmitter/receiver, the ODU comprising: a radio for receiving a signal having a first polarization and transmitted from a first one of the at least two independent transmitter ODUs of the microwave communication link; and a demodulator for receiving the signal from the radio, the demodulator determining one or more cross-phase noise estimates from each one of a plurality of transmitted pilot symbols of the signal having the first polarization, wherein cross-phase interference is introduced from a signal having a second polarization orthogonal to the first polarization and transmitted from a second one of the at least two independent transmitter ODUs of the microwave communication link, wherein the signal having the first polarization is compensated by the one or more cross-phase noise estimates, and wherein the ODU comprises a local oscillator which is independent from respective local oscillators of all other receiver ODUs of the at least two independent receiver ODUs. ### Claim 15 (depends on 14) The ODU of claim 14 wherein the plurality of transmitted pilots comprises two consecutive pilots. ### Claim 16 (depends on 15) The ODU of claim 15 wherein the plurality of pilots comprises four consecutive pilots wherein six cross-phase noise estimates are determined from the four consecutive pilots. ### Claim 17 (depends on 14) The ODU of claim 14 wherein compensating is performed according to a formula: rH,H−ejφrH,V=sHPejθ13 where rH,H is a channel equalized received horizontally polarized signal; ejφrH,V is a cross-phase interference from a channel equalized vertically polarized signal on the horizontally polarized signal where φ is the cross-phase noise component; and sHPejθ13 is a horizontally polarized transmitted pilot signal affected with phase noise of local oscillators ejθ2 of a transmitter and ejθ2 of a receiver for the horizontally polarized signal of the microwave communication link. ### Claim 18 (depends on 14) The ODU of claim 14 wherein compensating is performed according to a formula: rV,V−ejφrV,H=sVPejθ24 where rV,V is a channel equalized received vertically polarized signal; ejφrV,H is a cross-phase interference from a channel equalized horizontally polarized signal on the vertically polarized signal where φ is the cross-phase noise component; and sVPejθ24 is a vertically polarized transmitted pilot signal affected with phase noise of local oscillators ejθ2 of a transmitter and ejθ4 of a receiver for the vertically polarized signal of the microwave communication link. ### Claim 19 (depends on 14) The ODU of claim 14 wherein the cross-phase compensation factor further comprises: generating channel approximation pairing for each of the plurality of transmitted pilot symbols; solving each pairing to provide the one or more cross-phase noise estimates; and determining a minimum metric from the one or more cross-phase noise estimates. ### Claim 20 (depends on 19) The ODU of claim 19 wherein compensating is performed according to a formula: rH,H−ejφrH,V=sHPejθ13 where rH,H is a channel equalized received horizontally polarized signal; ejφrH,V is a cross-phase interference from a channel equalized vertically polarized signal on the horizontally polarized signal, where φ is the cross-phase noise component; and sHPejθ13 is a horizontally polarized transmitted pilot signal affected with phase noise of local oscillators ejθ2 of a transmitter and ejθ4 of a receiver for the horizontally polarized signal of the microwave communication link; wherein the noise compensation factor is determined by solving for each set of transmitted pilot symbols by: φ = angle ⁡ ( r H , H , m ⁢ s HP , n - r H , H , n ⁢ s HP , m r H , V , m ⁢ s HP , n - r H , V , n ⁢ s HP , m ) where m and n are a number of the pilot symbol between 1 to M transmitted pilot symbols. ### Claim 21 (depends on 19) The ODU of claim 19 wherein compensating is performed according to a formula: rV,V−ejφrV,H=sVPejθ24 where rV,V is a channel equalized received vertically polarized signal; ejφrV,H is a cross-phase interference from a channel equalized horizontally polarized signal on the vertically polarized signal, where φ is the cross-phase noise component; and sVPejθ24 is a vertically polarized transmitted pilot signal affected with phase noise of local oscillators ejθ2 of a transmitter and ejθ4 of a receiver for the vertically polarized signal of the microwave communication link; wherein a cross-phase compensation factor associated with a first set of pilot symbols is interpolated with a cross-phase compensation factor associated with a second set of pilot symbols to compensate the signal having the first polarization. ### Claim 22 (depends on 14) The ODU of claim 14 wherein compensating the signal further comprises: determining a first compensation factor for a first set of pilot symbols; and determining a second compensation factor for a second set of pilot symbols received subsequent to the first set of pilot symbols; wherein the determined first and second compensation factor are applied to data received between the first set of pilot symbols and the second set of pilot symbols. ### Claim 23 (depends on 22) The ODU of claim 22 wherein cross-phase compensation of the signal is performed by obtaining a linear approximation between the first and second compensation factors and by applying the approximation to data received between the first and second sets of pilot symbols. ### Claim 24 (depends on 15) The ODU of claim 15 wherein the cross-phase noise compensation factor is determined by a Wiener filter approximation on the cross-phase noise estimates of pilot symbols based upon N groups of consecutive pilots. ### Claim 25 (depends on 14) The ODU of claim 14, wherein determining the cross-phase noise estimates is performed by the ODU independently from all other receiver ODUs of the at least two independent receiver ODUs.