Self-interference produced by the transmitted signal can be a billion times stronger than the desired received signal and thus has a significant impact on RF and digital properties of the desired signal [20]. In general, self-interference includes: linear components: leakage from Tx to Rx, possible reflections due to antenna/transceiver, and reflections from environment. The main signal power could be about the same level of the Tx power; nonlinear components: nonlinear distortion due to Tx power amplifier (PA), which is about 30 dB lower than the main signal in linear self-interference [2]; Tx noise: due to PA noise and phase noise, which is about -50 dBm [2]. Assume that in an indoor environment, noise figure (NF) is 6 dB; bandwidth (BW) is 20 MHz; and implementation margin (Io) is 5 dB (note: thermal noise Nthermal = k*T*BW, k is Boltzman’s constant (=1.38 x 10-23 J/K), absolute temperature T=290 K, BW is channel bandwidth) The noise floor is calculated as: 114 dBm = -90 dBm. – If the transmit power equals 20 dBm, it requires an FD receiver to have an ability to cancel interference in a level of 20-(-90) = 110 dB in order to reduce the main signal to the noise floor power level. The self-interference channel impulse response can be appropriately modelled as shown in [20] where the parameters of the internal portion of the self-interference channel impulse response depend on the internal antenna structure. They are quasi-static and can be calculated/estimated based on the antenna structure specifications while the parameters of external portion of the self-interference channel impulse response depend on the external possible reflectors in the surrounding environment and are time-varying. Figure 4 illustrates the locations of various parasitic self-interference mechanisms present in a full duplex transceiver that need to be mitigated. Figure 4 Self interference mechanisms in a Full Duplex transceiver. Whereas Figure 5 illustrates the relative magnitudes of the transmitted and received signal levels in a full duplex use case along with the relative magnitudes of the signal levels after each stage of process. Received signal power Path loss The received signal power can be calculated using the following Friis transmission equation: where the terms in the equation are: Pr Received signal power in watts — Pt Peak transmit signal power in watts — Gt Transmitter gain —
Self-interference produced by the transmitted signal can be a billion times stronger than the desired received signal and thus has a significant impact on RF and digital properties of the desired signal [20]. In general, self-interference includes: linear components: leakage from Tx to Rx, possible reflections due to antenna/transceiver, and reflections from environment. The main signal power could be about the same level of the Tx power; nonlinear components: nonlinear distortion due to Tx power amplifier (PA), which is about 30 dB lower than the main signal in linear self-interference [2]; Tx noise: due to PA noise and phase noise, which is about -50 dBm [2]. Assume that in an indoor environment, noise figure (NF) is 6 dB; bandwidth (BW) is 20 MHz; and implementation margin (Io) is 5 dB (note: thermal noise Nthermal = k*T*BW, k is Boltzman’s constant (=1.38 x 10-23 J/K), absolute temperature T=290 K, BW is channel bandwidth) The noise floor is calculated as: – 114 dBm = -90 dBm. If the transmit power equals 20 dBm, it requires an FD receiver to have an ability to cancel in a level of 20-(-90) = 110 dB in order to reduce the main signal to the noise floor power level. The self-interference channel impulse response can be appropriately modelled as shown in [20] where the parameters of the internal portion of the self-interference channel impulse response depend on the internal antenna structure. They are quasi-static and can be calculated/estimated based on the antenna structure specifications while the parameters of external portion of the self-interference channel impulse response depend on the external possible reflectors in the surrounding environment and are time-varying. Figure 4 illustrates the locations of various parasitic self-interference mechanisms present in a full duplex transceiver that need to be mitigated. Figure 4 Self interference mechanisms in a Full Duplex transceiver. Whereas Figure 5 illustrates the relative magnitudes of the transmitted and received signal levels in a full duplex use case along with the relative magnitudes of the signal levels after each stage of process. Received signal power Path loss The received signal power can be calculated using the following Friis transmission equation: where the terms in the equation are: Pr — Received signal power in watts Pt — Peak transmit signal power in watts Gt — Transmitter gain interference
11-18-0498-08-00fd-fd-tig-report.docx