ADVANCED UPLINK MULTIPLE ACCESS SCHEME FOR SATELLITE CONTROL NETWORK

• US 20180167134A1
• Filed: 12/13/2016
• Published: 06/14/2018
• Est. Priority Date: 12/13/2016
• Status: Active Grant

• Current Assignee: Intelligent Fusion Technology, Inc.
• Original Assignee: Intelligent Fusion Technology, Inc.
• Inventors: MO, Zijian, WANG, Zhonghai, WANG, Gang, CHEN, Genshe, NGUYEN, Tien, PHAM, Khanh
• Granted Patent: US 10,090,910 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]

Abstract

In accordance with various embodiments, a method for uplink multiple accessing based on code division multiple access (CDMA) technology and a related system are provided. The method comprises: designing a practical uplink spreading waveform for a code division multiple access (CDMA) based SCN by leveraging a plurality of pseudorandom sequences and investigating a channel coding block and a modulation block for the CDMA based SCN; determining an uplink frequency sub-band division for the CDMA based SCN to optimize a tradeoff between a performance and an implementation cost of CDMA based SCN; and specifying a configuration of a control system of the CDMA based SCN.

Claims

1. An uplink multiple accessing method for satellite control network (SCN), comprising:

designing a practical uplink spreading waveform for a code division multiple access (CDMA) based SCN by leveraging a plurality of pseudorandom sequences and investigating a channel coding block and a modulation block for the CDMA based SCN;

determining an uplink frequency sub-band division for the CDMA based SCN to optimize a tradeoff between a performance and an implementation cost of CDMA based SCN; and

specifying a configuration of a control system of the CDMA based SCN.

2. The uplink multiple accessing method of claim 1, wherein the plurality of pseudorandom sequences include Walsh code and Gold code.

3. The uplink multiple accessing method of claim 2, wherein designing the practical uplink spreading waveform, and investigating a channel coding block and a modulation block include:

Receiving a plurality of raw control data streams;

channel coding and interleaving each raw control data stream to generate an encoded control data stream;

dividing each encoded control data stream into an I signal modulated by an in-phase modulation, and a Q signal modulated by a quadrature-phase modulation;

spreading the I signal and the Q signal of each encoded control data stream by a corresponding orthogonal variable spreading factor (OVSF) code spreader for separating each encoded control data stream with other encoded control data streams; and

modulating the I signal and the Q signal of each encoded control data stream to generate modulated signals that are suited to characteristics of transmission channel.

4. The uplink multiple accessing method of claim 3, after channel coding and interleaving each raw control data stream and before dividing each encoded control data stream, the method further comprises:

generating a long code by a 42 bits maximum length shift register; and

scrambling each encoded control data stream with the long code.

5. The uplink multiple accessing method of claim 3, after spreading the I signal and the Q signal of each encoded control data stream and before modulating the I signal and the Q signal of each control data stream, the method further comprises:

performing a bit-by-bit XOR operation to each control data stream with the Gold code by a gold code spreader to increase an interference tolerance of the encoded control data streams.

6. The uplink multiple accessing method of claim 3, wherein spreading the signal and the Q signal of each encoded control data stream includes:

generating a tree-structured OVSF code to provide orthogonality for separating each encoded control data streams,

wherein the tree-structured OVSF code has at least one root that derives two branches, and each branch has a codeword extended from the root.

7. The uplink multiple accessing method of claim 3, wherein:

modulating the I signal and the Q signal of each encoded control data stream is performed by a filtered Quadrature Phase Shift Keying (QPSK) data modulator.

8. The uplink multiple accessing method of claim 3, wherein modulating the I signal and the Q signal of each encoded control data stream is using at least one of the following modulation algorithm:

Binary phase-shift keying (BPSK), Quadrature Phase Shift Keying (QPSK), filtered BPSK, filtered QPSK, minimum-shift keying (MSK), Gaussian Minimum Shift Keying (GMSK), and 8 Phase Shift Keying (8PSK).

9. The uplink multiple accessing method of claim 1, wherein:

the spread plurality of encoded control data streams have a same bandwidth for all users; and

an uplink frequency sub-band division spreading factor of for different users are different.

10. The uplink multiple accessing method of claim 9, wherein:

the uplink frequency sub-band division spreading factor includes a processing gain, which is derived from a minimum self-interference, an affordable hardware/software modification, and a negligible interference with a co-existing narrowband system.

11. The uplink multiple accessing method of claim 10, wherein determining the processing gain includes:

calculating a jamming margin to quantitatively describe a relation between the processing gain and an interference tolerance of the CDMA based SCN over the co-existing narrowband system.

12. The uplink multiple accessing method of claim 10, wherein the jamming margin is calculated by using an equation of:

A/J=G_s−

E_b/N₀,

wherein A/J is the jamming margin, G_s is the processing gain defined by a ratio of a spread spectrum bandwidth to an information bandwidth, and E_b/N₀ is a minimum required output signal to noise ratio per bit.

13. The uplink multiple accessing method of claim 1, wherein specifying the configuration of the control system of the CDMA based SCN includes:

analyzing a relationship among a spreading bandwidth, a channel separation, a chip rate and a roll-off factor of the CDMA based SCN,

developing a channelization scheme for the control system of the CDMA based SCN, and

estimating a number of supported satellites for the channelization scheme.

14. The uplink multiple accessing method of claim 13, wherein the channelization scheme includes an inter-beam asynchronous spreading code assignment and a spectrum management.

15. The uplink multiple accessing method of claim 14, wherein the inter-beam asynchronous spreading code assignment includes:

assigning a unique scrambling code for each remote tracking station antenna beam; and

assigning a unique channelization spreading code for each user within an antenna beam.

16. The uplink multiple accessing method of claim 15, wherein:

the unique scrambling code is Gold code; and

the unique channelization spreading code is orthogonal variable spreading factor (OVSF) code.

17. The uplink multiple accessing method of claim 13, wherein the spectrum management includes:

designing each channel to provide the processing gain, the spreading bandwidth, a data rate, and a guard band requirement, wherein the guard band requirement is derived based on a Doppler Effect caused by mobility of satellites.

18. The uplink multiple accessing method of claim 13, wherein estimating the number of supported satellites includes:

generating an equation of a probability of bit rate error for a satellite control service by using a Bit Signal-Noise-Ratio (BSNR) degradation factor for the satellite control service;

obtaining the BSNR degradation factor based on a polarization isolation factor among antenna beams in the one channel;

determining a maximum supporting users using the equation.

19. The uplink multiple accessing method of claim 18, wherein:

the equation of the probability of bit rate error for the satellite control service in an i^th channel with a corresponding number of users N_i is

20. A system for uplink multiple accessing for satellite control network (SCN), comprising:

a hardware processor that is programmed to;

design a practical uplink spreading waveform for a code division multiple access (CDMA) based SCN by leveraging a plurality of pseudorandom sequences and investigate a channel block and a modulation block for the CDMA based SCN;

determine an uplink frequency sub-band division for the CDMA based SCN to optimize a tradeoff between a performance and an implementation cost of CDMA based SCN; and

specify a configuration of a control system of the CDMA based SCN.