A spectrum sharing transmission method suitable for VSAT star network

Abstract

The present invention discloses a spectrum sharing transmission method suitable for VSAT star network, which aims to solve the problem of limited number of small stations served at the same time due to the lack of frequency resources of satellite transparent repeaters. The method allocates a main station and multiple small stations in the same frequency band, and the small stations occupy different frequency resources in the frequency band. The satellite-borne repeater mixes the received main station and small station signals and transmits them downlink. The small station directly demodulates the main station signal. The main station first demodulates the main station signal, then re-modulates it and eliminates it in the aliased signal, and then filters it according to the frequency of each small station signal to demodulate the small station signal of each channel. The method allows the main station and small station signals to share the repeater bandwidth, and there is no need to divide frequency resources for small stations separately, which increases the number of small stations that access the network at the same time and achieves the improvement of spectrum efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of VSAT satellite communication, and in particular relates to a spectrum sharing transmission method suitable for a VSAT star network. Background Art

[0002] VSAT is a satellite communication network composed of a main station and several small-aperture terminals (small stations). The main station is equipped with a large-aperture antenna and has a strong ability to send information, and can transmit high-speed data services to the small stations. The small stations are equipped with small-aperture antennas to transmit low-speed services and signaling information to the main station. In a common VSAT network, the satellite is equipped with a transparent transponder and adopts the FDMA transmission system. The system allocates different frequency resources to the main station and the small stations, and there is a certain protection interval in the transponder frequency band, which leads to the fact that the transponder frequency resources are not fully utilized. Even when the number of small stations increases, the system cannot simultaneously connect the small stations to the VSAT network.

[0003] In order to improve the spectrum efficiency of satellite transponders, PCMA technology of paired carriers has been widely studied, but PCMA mainly solves point-to-point transmission between earth stations and cannot be applied to VSAT multi-station networking scenarios. Although TDMA technology can solve the networking problem, allocating multiple stations to different time slots does not fully utilize time domain resources. Summary of the invention

[0004] In view of this, the present invention proposes a spectrum sharing transmission method suitable for VSAT star network, aiming to solve the problem of limited number of small stations served simultaneously caused by the shortage of frequency resources of satellite transparent repeaters.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] A spectrum sharing transmission method applicable to a VSAT star network comprises the following steps:

[0007] (1) The VSAT system determines the number of small stations N that can communicate simultaneously using the spectrum sharing transmission method based on the services being transmitted.

[0008] (2) The VSAT system allocates the same transponder frequency band to the master station and the small stations that communicate simultaneously. The small stations occupy different frequency resources within this bandwidth.

[0009] (3) The master station and the small station modulate their respective uplink signals on the carrier frequency allocated by the system and transmit the uplink signals simultaneously.

[0010] (4) The satellite transponder aliases the received signals from the main station and the small station to form a downlink aliased signal, which is then transmitted downlink via a wide-area beam.

[0011] (5) The main station receiver first demodulates the main station signal in the aliased signal, remodulates the demodulated information and eliminates it from the aliased signal, then performs parallel filtering according to the frequency of the small station signal to obtain the transmission signal of each small station, and then demodulates it to obtain the effective information of each small station.

[0012] (6) The small station receiver directly demodulates the received aliased signal to obtain the valid information of the main station.

[0013] In step (1), if the demodulation signal-to-noise ratio threshold of the given small station is ΓdB, the modulation signal powers of the master station and the small station are α watts and β watts respectively, and the antenna transmission gain of the master station is E 0 , the transmission gain of the small station antenna is E i , then the number of small stations N communicating simultaneously needs to meet the following conditions:

[0014] Compared with the background technology, the present invention has the following advantages:

[0015] The present invention can realize multi-small station networking without allocating additional repeater frequency bands for small stations, thereby improving spectrum resource utilization and being particularly suitable for VSAT networks with limited repeater frequency band resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of an application scenario of the present invention.

[0017] Figure 2 It is a schematic diagram of allocating frequency resources for the main station signal and the small station signal by the satellite transponder of the present invention.

[0018] Figure 3 It is a demodulation principle diagram of the master station receiver of the present invention.

[0019] Figure 4 It is a schematic diagram of the demodulation principle of the small station receiver of the present invention. DETAILED DESCRIPTION

[0020] The present invention is described in detail below with reference to the accompanying drawings.

[0021] A spectrum sharing transmission method suitable for VSAT star network, Figure 1 A VSAT satellite communication network consisting of N small stations and one master station is presented. The master station and the small stations can realize two-way communication through satellite.

[0022] Figure 2 The frequency bands occupied by the master station and the small stations are shown in the figure. The system allocates the same frequency band resources to the master station and N small stations, and the small stations occupy different frequencies of this frequency band. Among them, the signal power of the master station is higher than that of the small station.

[0023] Figure 3 The demodulation principle of the master station receiver is given.

[0024] Figure 4 The demodulation principle of small station receiver is given.

[0025] This method allocates the master station and the small station in the same frequency band, and the satellite-borne transponder aliases the received signals of the master station and the small station to form an aliased signal for downlink transmission. The small station directly demodulates the master station signal in the aliased signal, and the master station first demodulates the master station signal in the aliased signal, remodulates the demodulated information and eliminates it in the aliased signal, then performs parallel filtering according to the frequency of the small station signal to obtain the transmission signal of each small station, and then demodulates it to obtain the effective information of each small station, thereby realizing signal transmission with high spectrum utilization.

[0026] Specifically, the method comprises the following steps:

[0027] (1) The VSAT system determines the number of small stations N that can communicate simultaneously using the spectrum sharing transmission method based on the services being transmitted.

[0028] Where, given that the demodulation signal-to-noise ratio threshold of the small station is ΓdB, the modulation signal powers of the main station and the small station are α watts and β watts respectively, and the antenna transmission gain of the main station is E 0 , the transmission gain of the small station antenna is E i , then the number of small stations N communicating simultaneously needs to meet the following conditions:

[0029]

[0030] (2) The VSAT system allocates the same transponder frequency band to the master station and the small stations that communicate simultaneously. The small stations occupy different frequency resources within this bandwidth.

[0031] (3) The master station and the small station modulate their respective uplink signals on the carrier frequency allocated by the system and transmit the uplink signals simultaneously.

[0032] (4) The satellite transponder aliases the received signals from the main station and the small station to form a downlink aliased signal, which is then transmitted downlink via a wide-area beam.

[0033] (5) The main station receiver first demodulates the main station signal in the aliased signal, remodulates the demodulated information and eliminates it from the aliased signal, then performs parallel filtering according to the frequency of the small station signal to obtain the transmission signal of each small station, and then demodulates it to obtain the effective information of each small station.

[0034] (6) The small station receiver directly demodulates the received aliased signal to obtain the valid information of the main station.

[0035] At this point, the spectrum sharing transmission method of the VSAT star network is completed.

[0036] In summary, this method allocates the master station and multiple small stations in the same frequency band. The small stations occupy different frequency resources in the frequency band. The satellite-borne transponder mixes the received signals of the master station and the small stations and transmits them downlink. The small stations directly demodulate the master station signal. The master station first demodulates the master station signal, then re-modulates it and eliminates it in the aliased signal, and then filters it according to the frequency of each small station signal to demodulate each small station signal.

[0037] The present invention allows the main station and small station signals to share the repeater bandwidth, and there is no need to allocate frequency resources for the small stations separately, thereby increasing the number of small stations that can access the network at the same time and achieving an improvement in spectrum efficiency.

Claims

1. A spectrum sharing transmission method applicable to VSAT star network, characterized in that The following steps are involved: (1) The VSAT system determines the number of small stations N that can communicate simultaneously in spectrum sharing transmission according to the services being transmitted; wherein the number of small stations N that can communicate simultaneously meets the following conditions: Among them, the demodulation signal-to-noise ratio threshold of the small station is ΓdB, the modulation signal power of the main station and the small station is α watts and β watts respectively, the antenna transmission gain of the main station is E0, and the antenna transmission gain of the small station is E i ; (2) The VSAT system allocates the same transponder frequency band to the master station and the small stations that communicate simultaneously, and the small stations occupy different frequency resources within this bandwidth; (3) The master station and the small station modulate their respective uplink signals on the carrier frequency allocated by the system and transmit the uplink signals simultaneously; (4) The satellite transponder aliases the received signals from the master station and the small station to form a downlink aliased signal, which is then transmitted downlink via a wide-area beam; (5) The master station receiver first demodulates the master station signal in the aliased signal, remodulates the demodulated information and eliminates it from the aliased signal, then performs parallel filtering according to the frequency of the small station signal to obtain the transmission signal of each small station, and then demodulates it to obtain the effective information of each small station; (6) The small station receiver directly demodulates the received aliased signal to obtain the valid information of the main station.

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