The mobile Internet and the Internet of Things are growing at an unprecedented rate, making mobile data services explosive. In the future technological evolution, richer communication modes, better user experience, and wider application development are important development directions. In order to cope with the challenge of massive traffic, the mobile network is developing towards the “wireless network without capacity limitationâ€, that is, the “big pipelineâ€, and the technology continues to make breakthroughs. In the future-oriented evolution of wireless technology, adapting to the application scenario and satisfying the user experience are the decisive factors.
Let's take a look at the top ten hotspots and new technologies in the wireless field with me, and communicate with friends in the industry.
First, the new multiple access method
In the future, 5G applications have focused on mobile broadband and the Internet of Things, and demand for high coverage, high capacity, low latency, and massive connectivity. 5G is bound to introduce new multiple access methods. Compared with various orthogonal/quasi-orthogonal multiple access schemes (TDMA/CDMA/OFDMA) in mainstream wireless communication systems, ZTE's new multi-access technology MUSA (MulTI-User Shared Access) is based on more advanced non- Orthogonal multiuser information theory.
MUSA uplink access enables high-reliability access to multiple times the number of users on the same time-frequency resource through innovatively designed complex-domain multi-code and advanced multi-user detection based on Serial Interference Cancellation (SIC); The resource scheduling process in the process can greatly simplify the system implementation of massive access, shorten the access time of massive access, and reduce the terminal energy consumption. The MUSA downlink provides a higher capacity downlink transmission than the mainstream orthogonal multiple access through innovative enhanced superposition coding and superposition symbol extension technology, and can also greatly simplify the implementation of the terminal and reduce the terminal energy consumption.
Second, the new code modulation and link adaptation technology
In the face of the core requirements of 5G, traditional link adaptation technology can not be satisfied, and the new code modulation and link adaptation technology can significantly improve system capacity, reduce transmission delay, improve transmission reliability, and increase the number of users access. . ZTE proposed soft link adapta (SLA), physical layer packet coding (PLPC), and Gbps high speed decoder (GHD).
The soft link adaptation technology improves the accuracy of the channel prediction and feedback methods, and solves the problem that the open-loop link adaptive OLLA has a long period, the impact of interference burst on performance, and the differentiation of QoS in various new scenarios of 5G. Demand (low latency / ultra reliable / high throughput / high speed mobile) and other issues. The physical layer packet coding technology can effectively solve the contradiction between large data packets and small coding blocks. Gigabit's ultra-high speed decoder technology can significantly increase the speed of single users and meet the requirements of 5G to support ultra-high speed user data rates.
Third, multi-antenna technology (Massive MIMO)
At present, wireless network traffic has exploded, and methods for improving wireless network capacity include: improving spectrum efficiency, increasing network density, increasing system bandwidth, and intelligent service offloading. Among them, large-scale antenna array technology has received more and more attention.
The basic feature of a large-scale antenna array is to obtain a more accurate beam steering capability than a conventional antenna array (no more than eight conventional antenna arrays) by arranging a large number of antenna arrays (from tens to thousands) on the base station side. Then, through spatial multiplexing technology, more users are served on the same time-frequency resource to improve the spectrum efficiency of the wireless communication system. Large-scale antenna arrays can suppress interference well, and bring huge interference suppression gains within and between cells, which further increases the capacity and coverage of the entire wireless communication system.
The advantages of large-scale antenna array technology are obvious, but how to fully exploit its potential huge gain under realistic constraints needs to be further studied, especially the research on key technologies such as channel information acquisition, antenna array design and codebook design. ZTE is related technology. The field has achieved certain advantages. In November 2014, ZTE Corporation and China Mobile successfully completed the world's first 128-antenna Massive MIMO field pre-commercial test.
Fourth, high frequency communication
At present, the spectrum of wireless communication below 6 GHz is already very crowded, the available bandwidth is limited, and there are a large amount of available spectrum from 30 GHz to 300 GHz, which are very attractive for wireless communication. The millimeter wave band has a large transmission loss relative to the existing cellular carrier frequency. Due to the short high frequency wavelengths, the transmitter and receiver per unit area can be configured with more antennas to achieve greater beamforming gain to compensate for additional path loss.
A base station using a high-gain antenna cannot use the preferred beam coverage to the receiving end until the weight is obtained. The terminal measurement is inaccurate, and the communication parties cannot perform data communication with the preferred beam weight. It is difficult to align the high-gain narrow beam in the mobile environment. If the optimal beam identification is not achieved, the terminal cannot complete the cell camp or barely camp the cell but the transmission quality is poor, which is contrary to the high rate expectation of the 5G network. Therefore, beam identification and tracking are the key issues in high frequency communication. It is necessary to join the beam discovery process in the high frequency communication system so that the base station and the terminal can discover each other and use the preferred beam for high data volume communication.
Five, wireless back
Wired backhaul makes the cost of dense deployment unacceptable and greatly limits the flexibility of base station deployment. Microwaves as backhaul require additional spectrum resources and increase the hardware cost of the transport nodes. In the case of occlusion, the channel quality of the microwave will be seriously affected, which limits the choice of site and reduces the flexibility of deployment.
Self-backhaul solves the problems of wired backhaul and microwave backhaul by using the same wireless transmission technology and frequency resources as the access link. However, Self-backhaul consumes the available resources of the access link, which limits the further increase of network capacity. Therefore, Self-backhaul capacity enhancement is an important research direction of UDN.
The technical means for enhancing the capacity of Self-backhaul include: further expanding the spatial freedom by multi-antenna technology; enhancing the receiving capability through the cooperation of the receiving end; exploiting the same service request by using content sensing technology, and improving resource utilization efficiency through multicast/broadcast; backhaul chain Dynamic resource allocation between the road and the access link.
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