Chapter 1044 A Brand New Form of Network?

For technicians who can participate in the Air Police 2000 project, they may feel numb when faced with a lot of information at first, but now, Chang Haonan has divided the types of data that need to be processed into two major categories. Naturally, someone soon figured out the joint:

"Mr. Chang, for the first category you mentioned, which requires time-sensitive data, it may be possible to use the UDP protocol in the Ethernet transport layer of the communication subsystem to achieve as much and as fast information transmission as possible. As for the second category, I think Just make certain improvements on the basis of the TCP protocol to make it adaptable to a mixed network medium of wired and wireless.”

This proposal quickly received some favorable feedback:

"I remember that a few years ago, some scholars proposed to set up a small relay station between wired and wireless transmission. The function is to simply copy the packets in both directions between connections. In this way, the first connection from the sender to the relay station appears. A transmission timeout causes the sender to slow down data transmission, and if a transmission timeout occurs on the second connection from the relay station to the receiver, retransmission is accelerated."

"..."

However, some people have raised objections:

"But the UDP protocol is not reliable enough in principle. Is it really suitable for transmitting military information?"

"But other than that, there seems to be no better choice..."

"..."

For a time, the entire conference room fell into a fierce debate, and no one could convince the other group of people in a short time.

However, Chang Haonan did not join in immediately. Instead, he returned to his seat and took a leisurely sip of water——

In his current position, although he is not the person in charge of the Air Police 2000 project, as long as he makes a statement, there is a high probability that it will become the final decision.

After all, the two chief engineers, Guo Lin and Liang Shaoxiu, had a close relationship with him.

Therefore, he is now gradually inclined to provide some guidance but does not immediately express opinions.

At least give others room to fully communicate.

However, before Chang Haonan could speak again, Guo Lin, who had been acting like a transparent boy just now, stood up:

"I think UDP is not a problem, because whether it is an early warning aircraft or a fighter jet, the transmission layer and control layer of their combat systems are separated. It is completely possible to use the UDP protocol at the transport layer and then use it at the application layer. Return verification method to ensure the reliability of data.”

In any case, Guo Lin is literally the chief designer responsible for the Air Police 2000 airborne equipment.

As a result, the surrounding area became quiet.

Guo Lin looked in the direction of Chang Haonan, and after confirming that the latter had no intention of adding anything, he continued:

"The problem still lies in TCP, how to optimize the performance of TCP for different network forms such as HF/VHF/UHF communication links and satellite communication links."

"A comrade did mention an idea just now. I'm sorry that I didn't notice who it was, but I guess this person is not from our Electronic Technology Group..."

Speaking of this, there was a slight smile in his tone;

"Because the communication method you mentioned does not actually conform to the semantics of TCP, it will be very complicated to implement at the engineering level..."

On the other side of the conference room, someone showed a slightly embarrassed expression.

He was indeed an engineer from the Haofei Group and was not from the communications field. He just suddenly remembered a paper he had seen in the past and chose to speak out.

It turned out to be a bit of a joke.

Fortunately, this is something outside the professional field, so no one cares too much.

Since Guo Lin's words had brought an end to the discussion, Chang Haonan no longer remained silent, but stood up again and returned to the front of the conference room:

"Actually... everyone has overestimated the difficulty of optimizing the TCP protocol."

He tapped the blackboard lightly and said:

"The relay platform we use, of course, does not refer to the relay between wired and wireless as the comrade just said, but the relay in the wireless communication process. In the future, it will be satellites, but in the current test, it is the stratosphere. Airship, this platform has passed the performance test.”

"Because of the use of brand-new network coding technology, extremely low bit error rates and delays can be guaranteed even in complex electromagnetic environments. Although I can't say it is at the same level as wired networks, it is at least better than in the past...or existing The wireless transmission technology is much more reliable.”

These words confused many people present -

Wasn't your old self the first person to say that the TCP protocol should be improved?

Why are you now saying that we overestimated the difficulty of this matter?

Facing a dozen confused faces, Chang Haonan didn't show any concern. Instead, he erased the small triangles and circles he had just drawn on one side of the blackboard and filled in a new diagram.

As he drew, he explained:

"Actually, the idea of ​​setting up a relay point between wired and wireless transmission cannot be considered problematic."

"Um?"

Guo Lin immediately couldn't hold himself tight.

He just vowed to criticize others. If he found out that he was wrong in the end, all the boomerangs would be pierced in his head.

Chang Haonan paused deliberately for a while, and then turned around and added:

"Of course, Mr. Guo's subsequent criticism is also correct."

"call--"

Guo Lin finally breathed a sigh of relief, and his blood pressure, which almost exploded, also dropped.

"We can add a probing agent to detect and cache TCP data segments sent to removable hosts, and the acknowledgment information returned."

Chang Haonan drew a reverse dotted arrow on the part representing the wired data segment:

"When the probing agent finds that a TCP data segment is stopped before the timer expires, but no acknowledgment is received from there, or a duplicate acknowledgment is received, it means that there is a problem with the wired part and the original data segment needs to be discarded Resend…”

"And if it is confirmed that everything is normal, but there is still a transmission failure in the entire transmission, it means that the problem lies in the wireless part..."

"The specific implementation strategy still needs some testing, but because the bit error rate is not high, the path MTU minus the header size of TCP and IP can generally obtain the best performance..."

"..."

The improvement plan proposed by Chang Haonan is not complicated. It will only take a few weeks or at most one to two months to complete. It is basically software or some small-scale hardware-level measures that can be easily operated in the cabin. , will not even affect the final assembly progress of the Air Police 2000 prototype.

As for the audience below, they looked at each other in confusion.

Although no one said it directly, the expressions on their faces clearly showed the same meaning——

Is that all?

When Guo Lin first discovered this problem, including when Chang Haonan led them into the lounge just now, the solemn atmosphere made people think that the entire Air Police 2000 project would be postponed because of this.

Is this the result?

And Chang Haonan naturally saw everyone's psychology.

"So far, we have only solved the optimization of the TCP protocol for several traditional communication links, so it is indeed relatively simple."

He took a step forward and said calmly:

"But don't forget, the information command system I just mentioned..."

At this time, the doubts on everyone's faces not only did not decrease, but actually increased.

After a while, someone tentatively asked:

"But... doesn't that command system also rely on these types of communication links to issue orders?"

"Not exactly."

Chang Haonan waved his hand:

"All the scenarios we are currently imagining have preset a center for the entire communication system, which is the early warning aircraft. Of course, it may also be a higher-level command headquarters, for the same reason."

"But in reality, for example, when troops are rapidly deploying and advancing on the battlefield, the communication center cannot move forward simultaneously with the front-line units due to safety or tactical considerations. In this case, the mobile network with a center cannot meet the needs. , but we need a new communication link that can quickly, temporarily, and automatically form a network..."

"Distributed communications?"

Soon, someone threw out keywords.

"Yes."

Chang Haonan affirmed:

"Thanks to our newly developed relay technology, wireless communications can also perform multi-hop forwarding with low loss and low delay. Therefore, we can use this advantage to design a new form of communication network."

When he said "brand new", there were several obvious breathing sounds coming from below.

No one thought that Mr. Chang was going to play such a big game——

So far, the cornerstones of modern human communication technology, such as network structures and communication protocols, are still built by developed countries.

For the sake of standardization and globalization, China also chose to adopt most of its contents.

After all, it is a process of making wheels.

It will probably take a few more years to challenge the first-mover countries in this regard.

But obviously, Chang Haonan no longer wants to wait.

Therefore, he is ready to first test the waters in the military field that does not pursue global integration.

Chang Haonan gave everyone a few seconds to recover from the shock.

Then, on to the real meat and potatoes:

"In addition to multi-hop forwarding, this network should also have the following characteristics."

"First, there is no center. All nodes have equal status in the system. It is a peer-to-peer network. Any node can join and leave the network at any time. Even if there is a failure, it will not affect the operation of the entire network."

"The second is self-organization. The layout or expansion of the network does not need to rely on any preset network facilities. The nodes coordinate their own behaviors through layered protocols and distributed algorithms. After the nodes are powered on, they can quickly and automatically form an independent network. network."

"The third is dynamic topology. Due to application background considerations, network nodes will move anywhere at any time, and may be powered on and off at any time. These will cause changes in the topology of the network, but the network itself must ensure smooth operation."

"Therefore, such a communication network is not only significantly different from ordinary cellular mobile communication networks and fixed communication networks in terms of architecture and network organization, but it also requires corresponding adaptation of communication protocols."

He returned to his seat, took a deep breath, and looked around:

"This is the most important and most difficult task in the next TCP optimization!"