Interference Co-Existence Analysis Between LTE And DTMB

LTE(Long Term EvoIution)with the key technology of OFDM/FDMA is the biggest new technology R&D project presented by 3GPP organization. Currently, LTE is developing rapidly in worldwide.The United States and Nordic countries has deployed commercial LTE network in 2010.In China, great effort has been devoted to LTE which has been chosen as the future direction of communication technology evolution by the three communication operators.But the core issues restricting to the development of Chinese LTE is planning and allocation of frequency resources.LTE system is experimented in 2.3 GHz by China Mobile.If the frequency range is not in accordance with the future frequency scheme,it will have a seriously negatively impact on industrial development and LTE-FDD of China Unicom and China Telecom also will be researched and tested as soon as possible in the future.It also needs clear frequency planning as guide.In respect of digital television,china issued the standard of Digital Terrestrial Multimedia Broadcast(DTMB)in 2006.Because DTMB adopts efficient coding compression technology to improve the spectral efficiency,a part of frequency resource will be spared which is called digital dividend.The range of the digital dividend is different in different countries and regions. The Chinese digital dividend is 698MHz-806MHz which makes LTE to deploy in the low frequency possibly.A part of the digital dividend was distributed to the mobile operators in the United States,Europe and Japan and China Television Broadcast Department declared that there is on objectction to the use of spectrum allocated to the fourth generation mobile communication.Digital dividend becomes a potential spectrum used to deploy LTE system. First of all,according to 3 GPP LTE and china digital broadcast television standard, the interference thresholds of the two systems are made certain in this paper.Then the interference between the two systems is calculated by deterministic analysis method in digital dividend spectrum when the two systems are in the adjacent channel.Meanwhile,LTE throughput loss caused by DTMB interference and coverage loss of DTMB caused by the interference is calculated by Monte Carlo simulation method.According to the simulation results,the necessary interference isolation between the two systems is calculated.Finally,the advantages and disadvantages of the three kinds of LTE systems deployed in digital dividend spectrum are analysed.The results of deterministic analysis and Monte Carlo simulation show that the interference of DTMB to LTE downlink and LTE uplink to DTMB is small.DTMB transmitter characteristics and LTE terminal block characteristics can meet the requirements.While the interference of LTE uplink to DTMB and LTE downlink to DTMB is great. Band isolation or other isolation measures must be adopted to ensure two systems co-existence.Although positive and negative duplex LTE-FDD can prevent one-link interference,other communication systems should be deployed in duplex spacing,so the additional protected band is needed to prevent interference. Therefore,the bandwidth efficiency is lower than the LTE-TDD.