FDD, or TDD, the important thing is integration.

4G Submission Telecom Technology

It is said that FDD technology should be mature in TDD technology. In fact, any technology or people will not be born mature, always after some experience will mature.

Choose this topic, I am looking for scold. However, please leave the first mouth, I have to cross, back 2006 years ago.

At that time, the world had not LTE, a group of communications bosses around the round table to play brainstorming, their theme is: Next generation mobile communication network What is it like? Despite all the holes in the brain, the hype, but finally reached a four-point consensus:

1. Identified the next generation of mobile communications technology called LTE.

2. Improve the performance of the network. For example, in the 20MHz bandwidth channel, the uplink peak rate to reach 50Mbps, downlink peak rate to reach 100Mbps; network Shiyanda 10ms; spectrum efficiency is at least 3 to 5 times times that of 3G (HSPA or EV); at least 60 VoIP calls per Cell/mhz, etc. , a large list of them.

3. Compatibility

The so-called compatibility is that LTE must be compatible with the existing network of operators, which is very important. This means that whether the access network, the core network, or terminal equipment, LTE technology compatible with the existing 2G, 3G, or even WiMAX, WiFi and other technologies; This also means that LTE must support a variety of spectrum allocations, channel bandwidth and duplex mode; this also means that the LTE network must support network sharing, Roaming and unified network management.

4. Cost

Your technology is good, the cost is too high, no one will ignore you! Cost, which is critical. Regarding the cost, must consider from two aspects: one is the technical aspect, one is the commercial noodles. Technically, they think of network IP, network structure simplification, spectrum efficiency and so on. In terms of commercialization, they have taken into account a very important point: the LTE ecosystem. This ecosystem must be bigger, so that more people to participate in the game, playing games more people, scale can be big, large-scale, the cost can be reduced.

To expand the scale of the ecosystem, you not only have to be compatible with GSM, WCDMA, but also compatible with TD-SCDMA; to scale up the ecosystem, you have to incorporate the frequency resources of the operators ' existing and various mobile communication systems into LTE; To expand the scale of ecosystems, You also have to support both FDD duplex mode and TDD duplex mode, because TDD is more duplex flexible.

To put it bluntly, you are compatible with both WCDMA and TD-SCDMA, you have the WCDMA band into LTE also to the TD-SCDMA band into LTE, so that you have to focus on WCDMA operators or equipment vendors see the Hope, Let the operators and equipment operators who are focused on TD-SCDMA see hope. To everyone Gao, with you play more people, the scale of the ecosystem can be bigger. In fact, 4G has been enough tenderness, you see 5G, ambition that is called Big!

Therefore, TDD is an essential part of the LTE standard, not without the mother and the white sent. It is not a supplement to the FDD, it is not non-mainstream, it is justifiable, is determined at the beginning.

So what's the difference between TDD and FDD? The main thing is that there are some differences in duplex mode.

Signalsresearchgroup (SRG) has conducted a very in-depth analysis of LTE standards, and its report shows that only 17.5% of all technical solutions submitted to 3GPP refer to duplex technology. In these 17.5%, only 7% of the documents belonging to the tdd,3.7% are attributed to FDD, while the remaining 6.8% discusses two modes of duplex.

To put it simply, although FDD and TDD differ in duplex technology, at least 80% of them are technically similar.

Why is that? Because duplex is only a small part of the LTE standard, TDD and FDD frame structures are different, but the core network is the same, other MAC layer, modulation mode, MIMO, control channel, etc. are the same.

Look back to think, TDD and FDD also so little difference, in exchange for so many partners to play the game, 3GPP is also quite profitable!

In addition, TDD is not a proprietary intellectual property, although mobile holding a large number of TDD frequency resources, and vigorously develop TDD, but TDD is not a TD-SCDMA evolution version. In fact, TDD and TD-SCDMA are also different in technology. LTE is an independent technical standard that incorporates TDD and FDD two duplex modes, neither the evolution of the 3G TDD version nor the evolution of the 3G FDD version.

TDD does not belong to China, nor is it the evolution of TD-SCDMA, so who does it belong to?

The authors are from all over the world in the 3GPP documentation on the LTE technology proposal. TDD part, from China is also only 19%; The FDD part, from China accounted for 12%, even the duplex technology part, from China only accounted for 13%.

Since the difference between the two is so small, TDD belongs to everyone, so why do so many operators love FDD?

This question, I think possible, is only possible, there are two reasons.

On the one hand, compared to the TDD,FDD has a better quality and richer spectrum resources, and allocated to FDD spectrum resources, a large part of our current network GSM/CDMA/WCDMA is using the spectrum resources, which seems to imply that our technology is more superior.

On the other hand, the traditional voice business is symmetrical business, in fact, from the mobile era, to a very mature GSM, and then still mature WCDMA, all the frequency distribution is in pairs appear, up and down the line using different frequency bands, but, to LTE, there are two ways, One is the FDD of the upper and lower frequency pairs, and the other is the TDD working on the same band.

The communicator is accustomed to the frequency pairs, we are very clear this mode how to plan the network, in pairs makes us feel very comfortable. The bands assigned to TDD are not what they are familiar with, and suddenly let them jump to the unfamiliar and not pairs of frequencies to plan the network, they are very reluctant, they will not hesitate to choose FDD.

So, there is a saying that FDD technology should be mature in TDD technology. In fact, any technology or people will not be born mature, always after some experience will mature.

Of course, the above is just speculation, regardless of the operator to choose which format, I think must be combined with their own resources and first consider the cost.

In short, whether it is FDD or TDD, each has its own advantages, each has its own shortcomings, in the communication to the trend of large integration, and the debate which strong, but also better think about the integration of the future!

Well, finally finished. Everybody reader now can open scold, I will roll far!

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