Riding the wind of rebirth

From what Zhou Zhi knew, it was indeed not outperforming, and the reason was simple. Once a satellite was put into orbit, it would be difficult to upgrade it, and it could only be replaced.

However, the cost of replacement is quite high, and the speed of launching a new generation of satellites cannot keep up with the speed of ground stations on the ground that are iterating according to Moore's Law.

This situation can only be achieved when Moore's Law basically becomes invalid, that is, when electronic components develop to the point where they no longer rely on high-precision top-level silicon oxide products and can support most of human communication application scenarios.

It will take about thirty years for this to become a reality.

"Yes, this is indeed a problem." Old Yu nodded in agreement.

"With so many problems, Mr. Yu, how are the domestic experts going to help us solve them?" Zhou Zhi knew that since these bigwigs from the Science and Technology Commission dared to raise the questions, they were already fully prepared. There was only one reason for doing so, which was to demonstrate the unique superiority of "Dongsanyi" over similar designs.

Sure enough, I heard Mr. Yu say: "The issues of application and market scenarios are what you are considering. Since you have such ideas, it means that you already have a more urgent need. Now we will only talk about our technology."

"The reason why the Iridium program needs so many satellites is because of the orbit it is in."

"According to the orbital altitude, communication satellites can be divided into low earth orbit, medium earth orbit, geostationary orbit, sun-synchronous orbit and inclined geosynchronous orbit. Satellite communication systems built on different orbits have different characteristics in terms of coverage, system capacity, transmission delay, satellite life and so on."

"Among them, low-orbit satellite constellations are more suitable for building large-scale satellite networks. If satellite Internet is to be formed, it seems to be an inevitable choice. Because low-orbit satellite communication systems have the advantages of short transmission delay, good stability, small link loss, and rich application scenarios. Of course, there are also many disadvantages. First of all, to achieve global coverage, too many satellites are needed. The advantages mentioned above are offset in the transmission between satellites."

"Of course, because there are so many low-orbit communication satellites and they present a meshed structure, even if there are problems with individual satellites, the entire network can still continue to provide reliable and continuous communication services, which constitutes a new advantage."

"But the cost of networking is much higher, mainly concentrated in the cost of launching. The cost difference between sending six rockets and launching 60 rockets will be in the billions, which constitutes a new disadvantage."

"In addition, based on the differences in application scenarios and business areas, low-orbit communication satellites are currently mainly narrowband mobile communication systems. The operating frequency bands of narrowband mobile communications are concentrated in the L and S bands. Because the frequency bands are low, the application scenarios can only be based on medium- and low-speed traditional handheld mobile communications and some Internet of Things services. They are low-throughput satellites."

"In addition, Iridium uses two representative modes of mesh networking. It seems quite advanced, but it forgets to consider the iteration speed of ground stations, which is the problem raised by Mr. Li Lehai just now. It artificially constructs the problem of iteration difficulty."

"And these problems do not exist on our East 3B."

"First, we can design the satellites to be high-orbit satellites. A single high-orbit satellite can cover a wider area. At the height of the geostationary orbit, one satellite can cover one-third of the earth, so the number needed is much less than that of low-orbit satellites."

"Of course, if there are fewer satellites, there is a possibility that a single satellite will be damaged, which will affect the normal operation of the entire satellite communication system. However, your requirements have already taken this into account. The extra satellites can not only balance the load, but also provide replacements when a single satellite has problems. The overall number will not be so large that the launch cost will change by an order of magnitude."

"Because the working frequency bands are concentrated in the Ku and Ka bands, the throughput is more than ten times that of low-throughput satellites. In this way, high-throughput satellite communications will not have the problem of insufficient bandwidth capacity of low-frequency and low-throughput satellites, and can support high-speed broadband Internet data transmission in the future." "Considering the iteration speed of future ground stations, we have tailored a new solution for everyone."

"If the Iridium satellite system is the 'Sky Star Skynet', we call this solution the 'Sky Star Ground Network'."

"Tianxing Skynet uses satellites as network transmission nodes and sets up intersatellite links between satellites. Users can directly access the satellite Internet without going through the ground network system. Its communication system can reduce the dependence on the ground network, and can flexibly select routes and manage networks. The number of ground stations is smaller and there is no need to deploy ground stations in other countries. Therefore, the complexity and investment cost of the ground segment are significantly lower."

"However, it also raises the requirements for user terminal equipment. Special equipment is needed for communication, and if it is to be connected to ordinary ground communication equipment, the network service of the ground station is also required."

"The so-called Sky-Star-Ground Network is different from the Sky-Star Sky-Net. We only use satellites as channels to connect user terminals with the gateway station. There are no inter-satellite links between satellites. Instead, they are connected to the ground communication network through the gateway station, and then with the help of ground stations distributed around the world, global network services are realized."

"If the Star Skynet receives requests from ground terminal devices at will, the Star Ground Network will first collect the communication requests of ground terminal devices that can be collected through the gateway station, and then transmit them to the satellite, and then the satellite will transmit them to other corresponding gateway stations or ground terminals."

"The simple explanation is that although it is satellite communication, any problem that can be solved on the ground will be solved on the ground first, and only when there is a necessary communication demand will it be sent to the satellite."

"This is a brilliant idea!" Li Laoer's eyes lit up and he immediately praised: "In this way, the overall call cost can be reduced a lot. The ground base station mode and the satellite base station mode can be used together, and it can also meet the communication needs between satellite phones, ordinary phones and mobile phones."

“But you just proposed to expand the redundancy and increase the number of satellites to fifteen. This gives us new ideas,” said Mr. Yu.

"Then please tell us quickly, Mr. Yu." Li Laoer is much more proactive than Li Laosan and Zhou Zhi in this regard. He has already seen a wide range of application scenarios.

For example, dual-mode mobile phones can automatically switch to satellite signals when there is no ground signal. This is something that does not exist yet and is very suitable for the needs of many special groups such as those in the ocean and geology fields.

"The idea is actually very simple." Yu Lao continued, "Since we have extra satellites, we can combine the Tianxing Skynet with the Tianxing Ground Network."

"Because our satellite orbits are very high, we can use three satellites to cover all areas of the earth except the North and South Poles. If we increase the number to five, we can achieve global satellite communications."

"But forwarding entirely through the ground network management center will undoubtedly increase latency in many communication scenarios."

"Now that we have ten more stars, we have a more perfect plan!" (End of this chapter)