TD-LTE globalization challenge: 3.5GHz become the new favorite of operators
Early comment on December 16 (Yue Ming) Today, with the global spectrum resources becoming depleted and the cost of network construction increasing, 3.5GHz has become the focus of global mobile operators for LTE network construction with its unique large bandwidth advantage.
Especially for TD-LTE, the 3.5GHz band has become an important TDD globalization frequency, which is of great significance for its expansion of the global industry scale. At present, countries including Japan, the United Kingdom, and Brazil have basically used 3.5 GHz for TDD, and the EU also recommends the use of TDD mode; even several operators have deployed TD-LTE networks at 3.5 GHz.
However, it should be pointed out that the development of the 3.5GHz TD-LTE industry is not a smooth one, especially in terms of spectrum usage. In order to simplify the network structure, reduce the terminal requirements, and control the cost of FDD/TDD convergence networking, some FDD operators have proposed a “full downlink†solution, which has a great negative impact on TD-LTE operation and industrial development.
3.5GHz into the new favorite of operators
With the advent of the digital flood era, the emergence of streaming media, clouds, social networks, VOIP, etc. has begun to change people's lives, so that users' demand for mobile broadband speeds has increased rapidly, stimulating the growth of network pipeline traffic demand, the value of spectrum. More and more prominent, the gap in spectrum resources is also growing.
For operators, to calmly deal with the current industrial structure, the first is to re-plant the original spectrum resources, such as clearing the original GSM/cdma network to the network for higher efficiency LTE; New spectrum resources to support the explosive growth of mobile broadband services. However, subject to the principle of mobile communication, the excessive frequency band in terms of coverage and penetration ability will undoubtedly increase the operator's construction and operation and maintenance costs, and even lose more.
In this context, 3.5GHz has become the new favorite of operators. Although the network operating frequency band is higher than the existing 2G/3G/4G network, the small cell used in the HetNet architecture can absorb the traffic; more importantly, the 3.5GHz band has a total of 400MHz spectrum, and the continuous bandwidth is large ( The average operator holds more than 40MHz), which is very suitable for supplementing the capacity of mobile broadband networks, and has attracted the attention of large operators around the world.
In March 2012, the world's first 3.5GHz TD-LTE network deployed by UK Broadband was officially commercialized and became the UK's first 4G commercial network. As of July 2013, seven 3.5GHz TD-LTE commercial network contracts have been signed worldwide. Global commercial deployment is accelerating, and 3.5GHz TD-LTE is welcoming a golden age.
3.5GHz spectrum allocation: TDD is becoming mainstream
After 3.5GHz becomes the focus of operators, the next problem will follow. For this new spectrum resource, whether it is TDD or FDD. From the current point of view, the TDD approach is gradually becoming the mainstream of 3.5GHz.
The industry has pointed out that the uplink and downlink bandwidth of the FDD spectrum is symmetrical, and the adaptability to the current unbalanced uplink and downlink traffic allocation ratio is poor. The FDD downlink spectrum is difficult to meet the downlink traffic demand; and the TDD mode can flexibly adjust the uplink and downlink ratio, which is very suitable. The characteristics of mobile Internet uplink and downlink asymmetric services.
Some LTE FDD operators began to consider how to use their TDD spectrum to complement their LTE FDD network. The joint operation of LTE FDD+TDD has become an important issue for many operators. As an important standard organization in the industry, 3GPP also launched a joint operation of FDD+TDD in June 2013 to accelerate the technology and industrialization process.
At present, Europe recommends the use of TDD mode in the 3.5GHz band, but FDD can also be used; Japan will allocate 3.5GHz spectrum in 2014, and has been identified as TDD mode, currently in the consulting stage; the US 3.5GHz is still in the hands of the military, Need to use spectrum sharing (LSA). In addition, the UK and Brazil also allocated this band as the TDD spectrum.
Globally, six operators around the world have deployed TD-LTE networks at 3.5 GHz, and more than a dozen operators are deploying or have released commercial plans. Several TD-LTE terminals and system devices support 3.5. GHz band.
Mode of doubt: the full downlink ratio will hinder the development of TD-LTE
It can be said that the industry is reaching more and more consensus on the value and distribution of the 3.5GHz spectrum; however, this does not mean that the development of TD-LTE will be smooth, because different operators have a great use of the 3.5GHz spectrum. the difference.
At the end of 2013, Japan began to collect the use of the 3.5 GHz spectrum. The operators reported that “the proposed 3.5 GHz adopts the TDD mode and there is no guard band between operatorsâ€. Japan's Tocomo Co., Ltd. plans to commercialize the spectrum immediately after its release, and began to actively promote the technical solution and project of "TD-LTE to introduce full downlink ratio" at the 3GPP RAN Plenary in early 2014.
The Telecommunication Research Institute of the Ministry of Industry and Information Technology pointed out in the "TD-LTE Technical White Paper" that the "full downlink" solution is beneficial for FDD operators to simplify the network architecture, reduce terminal requirements, and control the cost of FDD/TDD convergence networking, but for TD - LTE operations and industry development will have the following negative impacts:
First, the full downlink solution does not conform to the existing TDD system design principles, affecting the use of TDD spectrum. Since the full downlink ratio is not uplinked, it conflicts with the definition of TDD, and the frequency of using the ratio will not support the access of the terminal independently, which is inconsistent with the existing TDD system design principles. At this stage, once the TD-LTE full downlink ratio is introduced, it will directly impact the existing TDD spectrum usage. 3.5GHz is the most important global frequency band for TDD in the future. Japan is a country that deploys this band earlier. Once the band is used in full downlink mode, it will bring a bad demonstration effect on the global use of the 3.5GHz band.
Second, the full down approach has led to difficulties in spectrum regulation. At present, the global spectrum is divided into FDD and TDD, and some regions have a division of full downlink spectrum. However, if the whole downlink is introduced in TDD and the TDD spectrum is issued by the regulatory agency, the operator can directly use the TDD spectrum as a full downlink without any procedure, which will greatly plague the regulatory agencies.
Again, it will cause inter-operator coexistence issues, seriously affecting the deployment of conventional TD-LTE networks. TD-LTE supports the use of unprotected band spectrum between operators. When an operator uses unprotected band deployment, if an operator uses the full downlink ratio, the adjacent carrier adopts the existing TD-LTE slot ratio. The full downlink network directly interferes with the terminal access network of the adjacent frequency carrier, bringing "life and death problems" to the adjacent frequency carriers.
Finally, since there is no uplink transmission in the full downlink ratio, once the standard is introduced, there are risks of multiple TD-LTE terminal and terminal solutions, which adversely affects the TD-LTE industry in the development stage.
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