With the rapid development of mobile broadband, the network capacity is growing rapidly. As one of the main return modes of bearer network, microwave network is facing the dual challenges of super-large service capacity and densely deployed stations. Traditional band microwave (6-42GHz) spectrum resources are becoming increasingly scarce, bandwidth capacity is limited, it is difficult to meet the G-bit-level large bandwidth stations to return the demand, and E-Band microwave (80GHz) because of its rich bandwidth resources, large transmission capacity, low spectrum usage fees and high-frequency narrow beams to adapt to intensive deployment and other advantages, gradually from the traditional enterprises. The application of the industry market to the carrier class large bandwidth business bearer network development.
E-Band can deal with large capacity backhaul easily
E-Band is the microwave frequency band of 80GHz (71-76GHz and 81-86GHz), which is the highest frequency band for commercial microwave communication. According to the ITU-R spectrum allocation proposal (see Fig. 1), E-Band can be divided into 19 to 250 MHz subbands according to ETSI standards, with a wider modulation channel spacing than conventional microwave bands, enabling E-Band microwave communication systems to transmit more than G bits of capacity. Business. With high-order modulation, E-Band microwave can realize 1-5 Gbps, even more than 10 Gbps high capacity space port transmission.
E-Band microwave naturally has the capability of transmitting large capacity business. Taking a GSM/UMTS/LTE co-station as an example, assuming that its maximum return service capacity is 400 Mbps (of which LTE service is 300 Mbps), the conventional microwave (6-42 GHz) needs to occupy the maximum sub-band of 56MHz in the spectrum definition, which can only meet the transmission bandwidth requirement under 256 QAM modulation, which is almost not used. The maximum capacity of conventional band microwave can be achieved when capacity is enhanced.
For E-Band microwave, the transmission of 400 Mbps only needs one 250MHz (E-Band minimum subband) in the standard definition, which can be easily accomplished in the minimum modulation mode QPSK. If high-tone mode (such as 64QAM) and two 250MHz bands (500MHz) are used, the E-Band can achieve 2.5Gbps of ultra-large transmission bandwidth. For the actual deployment and planning of GSM/UMTS base station, although its single station capacity is generally less than 100 Mbps, but in larger aggregation stations, still face the need to converge to the core network to transmit Gbps-level service capacity, which means that E-Band is also suitable for the wireless transmission of metropolitan aggregation nodes.
In addition, E-Band is located in the 80GHz high frequency band with very narrow beam angle, the interference of spectrum reuse is relatively small, suitable for dense LTE access network, in the actual frequency planning can flexibly combine one or more 250MHz granular sub-bands, with adaptive modulation (AM) and adaptive channel adjustment (AC) technology, may be dense in urban areas. Set deployment of the return network more flexible and effective spectrum planning, convenient for multiple operators in the same area at the same time deploy E-Band microwave.
At present, more than 40 countries and regions around the world have opened E-Band bands. Most of them adopt free or low-cost strategies for the management of E-Band spectrum in order to encourage and promote more applications, alleviate the growing shortage of microwave spectrum resources, and minimize and protect the investment of operators in the spectrum.
Second generation E-Band for future telecom level applications
At present, E-Band microwave is mostly used in enterprise transmission scenarios. It has many shortcomings in transmission capacity, spectrum efficiency, network characteristics and management. Specifically, it only supports low modulation mode (BPSK), the maximum transmission capacity is only 1 Gbps, and needs to occupy 1 GHz frequency band to realize, and the spectrum efficiency is very low. Packet data characteristics, L2 or L3 functions through external switches or routers to achieve; Synchronization characteristics deficiency, no or only support synchronous ether, not support IEEE 1588v2; Lack of perfect network management functions, only provide the most basic configuration and management; Mainly used in the enterprise market, can not meet the requirements of telecommunications network equipment. High reliability; less deployment, narrow application area, high cost of devices and equipment, no scale delivery and maintenance capability, high overall TCO.
With the rapid development of LTE network, the demand for single-station transmission capacity will grow to G bit level in the future. LTE also puts forward higher requirements on data characteristics, synchronization, management and many other aspects. Obviously, the first generation of E-Band microwave products based on enterprise applications can not meet LTE's demand for large bandwidth, high performance and low cost return. To this end, leading microwave manufacturers have invested in the development of a new generation of E-Band products, the second generation of E-Band microwave to adapt to future telecommunications applications emerged.
In October 2012, Huawei took the lead in releasing the industry's first second-generation E-Band microwave products. The product's performance in transmission capacity, packet characteristics, synchronization, network management and TCO reduction has been substantially improved compared with the first-generation E-Band.
Super large transmission capacity and extremely high spectral efficiency
The second generation E-Band supports 64QAM high-pitch technology. Without using the same capacity enhancement technology as Ethernet frame head compression, 1.2Gbps transmission capacity can be achieved by using a 250MHz subband. If two 250 MHz subbands are combined, the transmission capacity of E-Band microwave single link can reach 2.5 Gbps (2.5 Gbps transmission capacity can be achieved with 1 250 MHz Ethernet frame compression technology), which can fully meet the future demand of G-bit base station for super-capacity service. Compared with the first generation E-Band, which takes up 1 GHz band to realize G-bit transmission, the spectrum utilization of the second generation E-Band is obviously improved greatly.
Advanced capacity enhancement technology
To minimize the impact of weather and environmental changes on the microwave link, the second generation E-Band microwave uses adaptive modulation and adaptive channel adjustment techniques to further enhance the link capacity and reliability, supports adaptive modulation levels ranging from QPSK to 64QAM up to 6 levels with weather changes, and 250MHz and 500MHz modulation. Frequency band dynamic adjustment, can provide from hundreds of Mbps to 2.5 Gbps of fine elastic large bandwidth pipeline, enhance the flexibility of site planning and deployment.
Another important technology to improve the transmission efficiency of carrier wireless packet service is Ethernet frame compression technology (also known as "bandwidth accelerator"). The second generation E-Band supports deep Ethernet header compression. It can compress the two-layer Ethernet header (L2 Ethernet) and three-layer IP header (UDP/IP/IPv4/IPv6) in the Ethernet packet in the microwave space-port link. The transmission efficiency of short packet packets (<128Bytes) with large frame header ratio can be improved by 50%-60%. Because LTE services often contain a large proportion of short packets, the application of Ethernet header compression technology can significantly improve the throughput of E-Band microwave in transmitting LTE packet services.
Perfect clock synchronization mechanism
Clock synchronization is an important step in the deployment of microwave bearer network. The first generation of E-Band microwave only supports synchronous Ethernet technology to provide frequency synchronization, which can not meet the phase synchronization requirements of LTE service bearer. Second-generation E-Band microwave supports synchronous Ethernet and full-mode IEEE 1588v2 (BC/OC/TC) deployment in various scenarios, and adopts out-of-band synchronous transmission mechanisms to ensure accurate transmission of synchronous information in packet networks.
Rich Ethernet data and network management features
Second-generation E-Band has rich network and management features: device/link/network-level protection mechanism; full-scale L2 Ethernet features; deep-level end-to-end QoS and SLA support, especially L2 OAM, which can timely complete all kinds of fault detection and location in complex networks; support MPLS-TP to provide reliable end-to-end packet service delivery. And management.
Significantly reduce TCO
In addition to the lower spectrum usage cost of the E-Band band itself, the second generation of E-Band products also use the design of telecommunication-grade products to provide high reliability; high-frequency spectrum efficiency and bandwidth can greatly reduce the unit bit transmission cost and power consumption; compact outdoor equipment structure, multi-GE ports easy to expand; unique USB port configuration advantages For fast start and backup, multi-functional (service/power/network management) line connection exempts tower maintenance; uses a network management platform that integrates with optical/router/microwave end-to-end... These characteristics can significantly reduce the TCO of carriers.
Second-generation E-Band microwave can be used in large bandwidth convergence links and optical network ringing, macro-station backhaul and high-density small cell micro-station access scenarios. It can well meet the needs of operators to build high-quality and ultra-wide bandwidth backhaul network. It is increasingly favored by operators all over the world. Vodafone, France Telecom, Deutsche Telecom, Spain and so on. Leading multinational operators such as Dental Telecom, Norwegian Telecom and Russian MegaFon have launched a second-generation E-Band business process. According to Dell'Oro's forecast, the E-Band-dominated mega-capacity microwave market will continue to grow at an average annual rate of up to 26% over the next five years. E-Band products and technologies are also in constant development. Combining high-tone and MIMO wireless transmission technologies, the transmission bandwidth of E-Band is expected to reach 5-10 Gbps in the future, making microwave truly a reliable transmission platform with "fiber-level" capacity.