Research On Harq For Space Information Networks Based On Network Coding

Compared with the traditional terrestrial network,the Space Information Network(SIN)will be built into an information network with global wide-area coverage,wireless broadband access,and efficient integration of heterogeneous services.The characteristics make it necessary to use space information networks to solve information needs.In the current communication equipment quantity index continues to grow,increasing demand high data rate services,personalized needs improving user data,under the condition of communication scenarios more rich,under the condition of limited bandwidth improve the maximum throughput of network,improve the effectiveness of the space information network transmission is urgently needs to solve the problem.As the hardware capabilities of devices continue to increase,network coding becomes an effective way to further improve the throughput and efficiency of SIN.It can use the operation of network nodes and the cooperation between nodes to achieve the result of improving communication efficiency.Based on SIN,we proposes Network Coded Hybrid Automatic Repeat Request(NCed HARQ)mechanism,designs corresponding protocol transmission process under different application scenarios,deduces theoretical performance indexes and conducts simulation verification.Specific research contents are as follows:In the second chapter,based on the typical communication scenario of space information network,combined with the characteristics of network coding,we propose the general flow of NCed HARQ transmission mechanism in space information network.Based on the communication scenario,the applicability of network coding is analyzed,and the NCed HARQ mechanism is divided into three phases,and the applicable scenarios of each phase of the NCed HARQ transmission mechanism are distinguished.For the fading channel model of SIN,the Laplace transform tool and Matrix exponential distribution are used to derive the related theorems for the NCed HARQ theoretical performance index.On the basis of this,for the multiple unicast flow data services in the typical communication scenario of the space information network,the second and third phase transmission mechanisms in NCed HARQ can be adopted.In the third chapter,the NCed HARQ transmission mechanism of various unicast streams is analyzed,and the theoretical expressions of retransmission times and throughput under the shaded fading channel are derived,and compared with the theoretical expression derived using the ME distribution.The simulation verifies that both derivation methods can calculate the exact theoretical value of the relevant performance indicators.In the fourth chapter,we first consider the scenario where two nodes communicate with each other through satellite relay in the space information network.In thethree-phase network coded bidirectional relaying(NCBR)scenario,the first and third phase transmission mechanisms in NCed HARQ are adopted.The theoretical calculation formula of throughput of NCBR interactive transmission mechanism is derived.The relationship between average SNR,channel transmission rate and throughput is analyzed,and the optimal channel transmission rate under specific SNR interval is given.Considering the interactive transmission scenario between the backbone satellite nodes and multiple ground devices in SIN,the all three phases of the NCed HARQ mechanism can be used to describe the information transmission process in the scenario.The theoretical calculation formula of throughput of NCed HARQ interactive transmission mechanism is also given.In summary,the NCed HARQ transmission mechanism based on network coding can be applied to a variety of typical business scenarios,and effectively improve the system throughput,which provides a certain guiding significance for the application of network coding technology in future SIN.