25Gbps "NG-PON2+" for backbone for 5G base stations

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[Access line 10Gbps road] (8th)

Since NTT East launched the Internet connection service "B FLET'S" in 2001, its speed has been increasing from the original 10m/100 Mbps since 2001, and Sony Network Communications Co., Ltd. in 2015.With the new plan of "NURO Hikari" that started providing, we finally reached 10Gbps.In 2017, 10Gbps Internet connection services are available in many areas, with the expansion of the target area of "NURO Hikari 10G".This time, we will explain the details of the 4x10Gbps "NG-PON2" and the status of standardization of "NG-PON2+" of 25 Gbps, which is standardized as a successor standard.(Editorial department)

Last time, I explained the outline of the specifications of "NG-PON2" with a rush, but let's add a little more.First of all, in October 2015, ITU-T "G.The standardization was completed as "989", but the iTu-T worked on NG-PON2 until 2017.This was "G" in August 2017.989.2 Amendment 2 "is completed.Following this, the iTu-T is currently working on "NG-PON2+".

As I mentioned a little last time, in NG-PON2, 10Gbps per wavelength became one wall.If it was a standard that simply oscillated at a speed of 10Gbps or more, there was already a "100GBASE-LR4" that could oscillate at 25Gbps at this time, but the problem is that the cost and size are very compatible with PON.It was that.

Similarly, the 100g Ethernet for short-distance, which is important, is only 10Gbps per wavelength in 2007 for the same reason, and the 4-piece bundle is 40GBASE-SR4, and 100 GBASE-SR10.It was operated as.

However, it was not easy to use 10 bundles as expected, and the cost increased as the wiring increased, so there was a debate about whether it could be managed a little more.

So IEEE was "P802 in 2012.A WORKING GROUP called 3BM (40GB/S and 100GB/S Fiber Optic Task Force).I explored how to speed up.However, looking at the initial discussion in Working Group, the laser itself is remained at 10Gbps because it can be used by changing the laser for 100GBASE-LR4 slightly, and instead uses a modulation method such as PAM4 and PAM8.There were various ideas, up to those that increased the effective speed.

However, from around here, the laser that can be oscillated at 25Gbps has begun to have a low price medal, so in consideration of practicality, technical difficulty, and cost, finally 25Gbps x 4 "100GBASE-".The standards such as "SR4" are "IEEE 802.It was standardized as 3bm.The good thing about this 100GBASE-SR4 is that it can be used as it is using an optical fiber for existing 40GBASE-T and can be passed through 100Gbps, which is ideal for upgrading existing users.

The standardization of 100GBASE-SR4 was completed during the specification of NG-PON2, which was a good opportunity to NG-PON2+.Of course, the 100GBASE-SR4 itself uses a wavelength of 850 nm, so it cannot be used for NG-PON2/NG-PON2+as it is, but if a certain number can be expected, if it is 25Gbps, it will be costly.It seems that the med is standing.That's why ITU-T set the target of NG-PON2+to 25Gbps.

The following documents are from the "Broadband FORUM BASE (Broadband Access Summit Event)" held in Las Vegas in October 2017.The basic concept is to keep the speed of NG-PON2 as it is, and raise only the speed from 10Gbps to 25Gbps.By the way, download (OLT → ONU) seems to have only 25Gbps and has no 10Gbps option, but upload (ONU → OLT) seems to have two types, 10Gbps and 25Gbps.

In the figure below, as you can see from the "Tubanle λ-Filter" on the download side, the default is 4 wavelengths and the eight wavelengths are multiplexed with WDM, and per ONU per ONU, 25Gbps, OLT per OLT.Then, it is a mechanism that allows the 100Gbps band to go down.

The reason why we are in a hurry to speed up is not for FTTH/FTTB/FTTO, but more accurately, 5g network's RRH (Remote Radio Head).As you know, 5G has begun demonstration experiments and field tests rapidly in the latter half of 2017, for example, in November 2017, NTT DOCOMO conducted a demonstration experiment with Huawei.

For these 5G, the technology called "C-RAN (Cloud Radio Area Network)" is included as an essential requirement.Speaking of C-RAN, recently it is likely to be misleading because it refers to the "advanced C-RAN", but the C-RAN here is not an advanced person.

In the past, when it comes to "base station", "base band device (BBU: Base Band Unit) + transmission / receiving unit (RRH: REMOTE RADIO HEAD)" is integrated, and a device may be placed around the root of the antenna.Most were.Between the BBU and the edge router, it is basically connected by Ethernet, and of course, "GE-PON" is used as a substance, so other equipment is often sandwiched between.Can happen.However, the basics are as shown on the left below.

On the other hand, in 5G, BBU and RRH are separated as shown in the right figure, and only RRH remains on the antenna side.The BBU is located away via an optical fiber, and the BBU and RRH are connected via another protocol called "Common Public Radio Interface".In addition to the CPRI, there is also a standard called "Obsai (Open Base Station Architecture Initial)", but here is it here.

The reason why a 5G base station has such a structure is that when there is a crowded antenna and an empty antenna, the load on the bandwinth cannot be handled well in the conventional structure.Because it is.Another problem was that it takes time to interfere with base stations and handover.

On the other hand, it has been said that it is better to collect the BBU in one place, distribute the antenna and RRH, and adjust it according to the load status.The idea of C-RAN itself appears early in 2010, and for example, there are careers such as CHINA Mobile, which introduced it in 4G (that is, LTE).However, since it took time to standardize, the full -fledged introduction is 5G.

Now return to NG-PON2+.The reason why NG-PON2+requires a 25Gbps bandwidth is that the connection between the 5g Fronthaul (between the BBU and the RRH) is more than 10 times the bandwidth compared to the 4G generation and the delay time.To be done.

For example, in the case of outdoor experiments between NTT DOCOMO and Huawei, a delay of 1 ms or less is required (although this is not all necessary for all communications because it is a low -delay URLLC mode).Even now, LTE Advanced has a demonstration experiment of 1Gbps download speed, and if this is 5G, the required bandwidth will increase.

The opinion of the base station manufacturer is that the realization of this request is quite severe especially in urban areas, especially in urban areas, and if possible, I would like to raise it to 25Gbps.Of course, this situation depends on the circumstances of the country and region.For example, urban areas of developed countries require NG-PON2+, but in rural areas, NG-PON2 may be enough, and XGS-PON or XG-PON may be good for developing countries.

However, the standardization has already been completed until NG-PON2, and equipment is being prepared.For example, in Japan, the Ito Cable System has already provided NOKIA's NG-PON2 equipment.After that, if you formulate NG-PON2+for the missing application, it seems that there will be some prospects for the 5G access line.

Therefore, regarding NG-PON2+, it is likely that the use in the form of ONU and OLT connected by Peer-to-PEER without the splitter for the time being.However, this NG-PON2+is assumed to be around 2020, so at this time, the usage style is probably only expected.

This time, we explained the specification details of "NG-PON2" and "NG-PON2+", which is a successor standard for its successor.Next time, we plan to explain the next generation PON "FOAS" and the "100G-EPON" standardization status of 100Gbps, which is the successor to IEEE's 10G-EPON.

Free technical writer.There are a wide variety of specialties, from CPU, memory, chipset, communication, OS, database, and medical relations.The homepage is http: // www.Yusuke Ohara.COM/