LTE(Long Term Evolution) project is the evolution of 3G, which improves and strengthens the air access technology of 3G, and adopts OFDM and MIMO as the only standards for its wireless network evolution. Under the spectrum bandwidth of 20MHz, the peak rate of downlink 100Mbit/s and uplink 50Mbit/s can be provided. The performance of cell edge users is improved, the cell capacity is increased and the system delay is reduced.
Main technical characteristics of LTE
3GPP describes LTE in detail from the aspects of system performance requirements, network deployment scenarios, network architecture, business support capabilities, etc. Compared with 3G, LTE has the following technical features [2][3]:
(1) The communication rate has been improved, with the downlink peak rate 100Mbps and the uplink 50Mbps.
(2) The spectrum efficiency is improved, and the downlink frequency is 5(bit/s)/Hz, which is 3-4 times that of R6HSDPA; The uplink is 2.5(bit/s)/Hz, which is three times that of r6hsu-PA2.
(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, supporting various system bandwidths between 1.25MHz-20MHz, and supporting "paired" and "unpaired" spectrum allocation. It ensures the flexibility of future system deployment.
(6) Reduce the wireless network delay: the subframe length is 0.5ms and 0.675ms, which solves the problem of backward compatibility, reduces the network delay, and the delay can reach U-plan.
(7) Improve the cell boundary bit rate, and improve 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 1 bit/second/hertz at the cell boundary.
(8) Emphasize backward compatibility and support the cooperative work of existing 3G systems and non-3GPP standard systems.
Compared with 3G, LTE has more technical advantages, such as high data rate, packet transmission, delay reduction, wide-area coverage and backward compatibility.
[Edit this paragraph]
Network structure and core technology of LTE
3GPP's work on LTE projects can be roughly divided into two periods: from March 2005 to June 2006, the SI(StudyItem) stage was completed, and the feasibility study report was completed; From June 2006 to June 2007, we completed the WI(WorkItem) phase and standardized the core technologies. The formulation of LTE related standard (3GPPR7) will be completed in mid-2007, and commercial products will be launched in 2008 or 2009. As far as the current progress is concerned, the development is about 3 months behind schedule [1], but with the efforts of the 3GPP organization, most of the system framework of LTE has been completed.
LTE adopts a single-layer structure composed of NodeB, which is beneficial to simplify the network, reduce the delay and achieve the requirements of low delay, low complexity and low cost. Compared with the traditional 3GPP access network, LTE reduces the number of RNC nodes. Nominally, LTE is the evolution of 3G, but in fact, it completely changed the whole architecture of 3GPP, and gradually approached the typical IP broadband network structure.
3GPP initially determined the architecture of LTE as shown in figure 1, which is also called evolved UTRAN architecture (E-UTRAN) [3]. Access network is mainly composed of evolved base station (eNB) and access gateway (aGW). AGW is a border node. If it is a part of the core network, the access network is mainly composed of the first layer eNB. The eNB not only has the functions of the original NodeB, but also can complete most functions of the original RNC, including physical layer, MAC layer, RRC, scheduling, access control, bearer control, access mobility management and inter-cell RRM. Node B and Node B will be directly interconnected in mesh mode, which is also a major modification of the original UTRAN structure.
[Edit this paragraph]
Operation and development of LTE
China Mobile is the largest mobile operator in the world by the number of users and market value. Previously, Vodafone in the UK, NTT DoCoMo in Japan and AT & amp； The world's major telecom operators T and Verizon have decided to adopt LTE technology. China Mobile will greatly promote the development of LTE technology, and LTE will continue the mainstream position of GSM in the post-3G era.
Arun Sarin, CEO of Vodafone, said at the Mobile World Congress in Barcelona yesterday that the group will join hands with China Mobile and Verizon to promote LTE technology, and LTE will become a clear direction for the future development of the industry.
At present, there are three main evolution paths of mobile wireless technology: one is WCDMA and TD-SCDMA, both of which evolve from HSPA to HSPA+ and then to LTE；; Secondly, CDMA2000 goes along EV-DO Rev.0/Rev.A/Rev.B, and finally reaches UMB；; ; The third is 802. 16m WiMAX routing. Among them, LTE has the most supporters, followed by WiMAX.
LTE is a technology developed by Ericsson, Nokia Siemens, Huawei and other major telecom equipment manufacturers in the world. Alcatel-Lucent and Nortel Networks in CDMA camp also have investments. 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 set up a joint venture with Japanese NEC to develop LTE.
Because Qualcomm has occupied the core technology patents in the 3G era, the LTE camp deliberately engages in OFDM to bypass Qualcomm's major technologies, and Qualcomm's position will definitely be weakened compared with the 3G era; At the same time, despite Qualcomm's lack of interest in UMB technology, the company also announced in Barcelona that it will launch a multimode LTE chipset in 2009, and Qualcomm will continue to make profits in this field.
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 3GPP LTE project include: providing downlink 100Mbps and uplink 50Mbps peak rates within 20MHz spectrum bandwidth; Improve the performance of users at the edge of the cell; Improve battery capacity; Reduce the system delay, the one-way transmission delay of user plane is less than 5ms, the migration time of control plane from sleep state to active state is less than 50ms, and the migration time from resident state to active state is less than100 ms; ; Support cell coverage with radius 100Km; It can provide >: 100kbps access service for 350Km/h high-speed mobile users; It supports paired or unpaired spectrum, and can flexibly configure various bandwidths from 1.25 MHz to 20MHz.
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.
In order to achieve these goals, the evolution of wireless interface and wireless network architecture is equally important. Considering the need to provide a higher data rate than 3G and the spectrum that may be allocated in the future, LTE needs to support a transmission bandwidth higher than 5MHz.
1. Lighting terminal equipment-optical transceiver
2. Line Terminal Equipment-Line Terminal Equipment
3. Long-term $ TERM evolution -3GPP long-term evolution
LTE: Long Term Evolution) 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 3GPP LTE project include: providing downlink 100Mbps and uplink 50Mbps peak rates within 20MHz spectrum bandwidth; Improve the performance of users at the edge of the cell; Improve battery capacity; Reduce the system delay, the one-way transmission delay of user plane is less than 5ms, the migration time of control plane from sleep state to active state is less than 50ms, and the migration time from resident state to active state is less than100 ms; ; Support cell coverage with radius 100Km; It can provide >: 100kbps access service for 350Km/h high-speed mobile users; It supports paired or unpaired spectrum, and can flexibly configure various bandwidths from 1.25 MHz to 20MHz.