1 Introduction
As one of the mainstream technologies of IMT-Advance, TD-LTE will make mobile networks truly enter the era of mobile broadband. Compared with the existing 2G and 3G mobile communication systems, TD-LTE puts forward higher requirements on the backhaul network in terms of high bandwidth, low latency, horizontal forwarding, and time-synchronous ground transmission.
â— First of all, bandwidth requirements have grown from a few megabytes and tens of megabytes in the 2G / 3G period to a few hundred megabytes in the LTE period.
â— Secondly, LTE needs to provide flexible QoS and stricter end-to-end delay. According to the 3GPP regulations, the real-time gaming service with the strictest delay requirements, the end-to-end unidirectional delay from user terminal to server is 50ms , The transmission delay between them needs to be within 10ms.
â— Third, LTE introduces the need for interconnection between adjacent base stations (X2 interface) and base station multi-homing (S1-Flex), resulting in the backhaul network changing from a point-to-point converged network to a point-to-multipoint or multipoint-to-multiple Point-based routing network, the existing 2G / 3G backhaul network can no longer meet this horizontal forwarding requirement.
â— Fourth, the TD-LTE air interface needs high-precision time synchronization, and the deviation of the air interface synchronization between different cells is not greater than 3? s, it is necessary to transmit high-precision time synchronization signals in the TD-LTE backhaul network.
The packet transport network (PTN) can provide high-efficiency multi-service bearer, with strong protection, OAM and network management functions, flexible statistical multiplexing and QoS capabilities, to meet the requirements of TD-LTE high bandwidth and low latency, but also for The TD-LTE system provides accurate time and frequency synchronization information transmission, so China Mobile has selected PTN as the main solution for TD-LTE backhaul. On the other hand, during the TD-LTE period, OTN equipment may gradually sink to the metropolitan convergence machine room. It is necessary to further promote OTN to support the 1588v2 time synchronization technology to realize OTN + PTN time synchronization ground transmission networking.
This article proposes solutions to key issues for the TD-LTE backhaul network requirements:
â— First of all, in order to meet the demand for high bandwidth, it is proposed to develop PTN towards a larger capacity and higher rate interface.
â— Secondly, in order to meet the requirements of horizontal forwarding, PTN provides two solutions: core layer enhanced L3 function and core layer docking with CE router.
â— Third, in order to meet the TD-LTE backhaul networking requirements, PTN is proposed to achieve full interoperability in business, OAM, protection, QoS and synchronization.
â— Fourthly, in order to meet the requirements of high-precision time synchronization, OTN and PTN are jointly networked to provide a time synchronization ground transmission solution. China Mobile has carried out a lot of research, testing and pilot work in the above four areas.
12-24W Solar Street Lights,12W Solar Street Light,15W Solar Street Light,124W Solar Street Light
Yangzhou Bright Solar Solutions Co., Ltd. , https://www.solarlights.pl