the research of LTE includes some generally considered important parts, such as the reduction of waiting time, higher user data rate, the improvement of system capacity and coverage, and the reduction of operating costs.
3GPP long term evolution (LTE) project is the largest new technology research and development project initiated by 3GPP in recent two years. This technology with OFDM/FDMA as the core can be regarded as? Quasi-4G? Technology. The main performance targets of the 3GPP LTE project include: the peak rate of 1Mbps downstream and 5Mbps upstream can be provided in the spectrum bandwidth of 2MHz; Improve the performance of users at the edge of the cell; Improve the cell capacity; Reduce the system delay, the one-way transmission delay in the user plane is less than 5ms, the migration time of the control plane from the sleep state to the active state is less than 5ms, and the migration time from the resident state to the active state is less than 1ms; Support cell coverage with a radius of 1Km; Can provide 35Km/h high-speed mobile users with >: 1kbps access service; Paired or unpaired spectrum is supported, and various bandwidths from 1.25 MHz to 2MHz can be flexibly configured.
main technical features of LTE
3GPP from? System performance requirements? 、? Network deployment scenario? 、? Network architecture? 、? Business support ability? LTE is described in detail. Compared with 3G, LTE has the following technical characteristics:
(1) The communication rate has been improved, with the downlink peak rate of 1Mbps and the uplink behavior of 5Mbps.
(2) the spectrum efficiency is improved, and the downlink is 5(bit/s)/Hz, (3-4 times that of the R6 version of HSDPA); The uplink is 2.5(bit/s)/Hz, which is 2-3 times of the R6 version of HSU-PA.
(3) With packet domain services as the main target, the overall architecture of the system will be based on packet switching.
(4)QoS guarantee, which guarantees the service quality of real-time services (such as VoIP) through system design and strict QoS mechanism.
(5) The system is flexible in deployment, and can support various system bandwidths between 1.25MHz-2MHz, and support? paired? And? unpaired? Spectrum allocation of. It ensures the flexibility of system deployment in the future.
(6) reduce the wireless network delay: the subframe length is .5ms and .675ms, which solves the problem of backwards compatibility and reduces the network delay, and the delay can reach u-plan <: 5ms，C-plan< 1ms。
(7) Increase the cell boundary bit rate, and increase the cell boundary bit rate while keeping the current base station position unchanged. For example, MBMS (Multimedia Broadcasting and Multicast Service) can provide a data rate of 1bit/s/Hz at the cell boundary.
(8) Emphasize backwards compatibility and support the cooperative operation of existing 3G systems and non-3GPP standard systems.
compared with 3G, LTE has more technical advantages, which are embodied in high data rate, packet transmission, delay reduction, wide area coverage and backwards compatibility.
Application and development of LTE
At present, there are three main evolution paths of mobile wireless technology: one is WCDMA and TD-SCDMA, both of which have evolved from HSDPA to HSDPA+ and then to LTE; Second, CDMA2 will eventually arrive at UMB along EV-DO Rev./Rev.A/Rev.B (a new scheme recently proposed by Motorola is that CDMA2 will also evolve to LTE in a certain way, and 3GPP2 will basically give up the UMB plan); The third is 82.16m WiMAX route. Among them, LTE has the most supporters, followed by WiMAX.
LTE is a technology developed by major telecom equipment manufacturers in the world, such as Ericsson, Nokia Siemens, Huawei, etc. Alcatel-Lucent and Nortel Networks in CDMA camp have also invested. CDMA has been losing power in recent years. Alcatel-Lucent has reduced its assets related to CDMA technical standards by $3.7 billion in Upper Zhou Chong, and will establish a joint venture with Japanese NEC to develop LTE.
As Qualcomm has occupied the core patent of technology in the 3G era, the LTE camp has deliberately engaged in OFDM to bypass Qualcomm's major technologies, and it is certain that Qualcomm's position will be weakened compared with the 3G era; At the same time, despite the lack of interest in UMB technology in Qualcomm, the company also announced in Barcelona that it will launch a multimode LTE chipset in 29, and Qualcomm will continue to make profits in this field.