Vehicular ad hoc networks(VANETs)that use the IEEE 802.11p communication standard face a number of challenges,not least when it comes to safety messages on the VANET control channel(CCH)where short delay times and rel...Vehicular ad hoc networks(VANETs)that use the IEEE 802.11p communication standard face a number of challenges,not least when it comes to safety messages on the VANET control channel(CCH)where short delay times and reliable delivery are of pri-mary importance.In this paper we propose a vehicular machine-to-machine(VM2M)overlay network that uses Long Term Evolu-tion(LTE)physical random access channel(PRACH)to emulate VANET CCH.The overlay network uses dedicated preambles to separate vehicular traffic from regular LTE traffic and a cartier sense multiple access with collision avoidance(CSMA-CA)layer similar to the one used in IEEE 802.15.4 to avoid the four step handshake and the overhead it incurs.The performance of the pro-posed overlay is evaluated under a wide range of PRACH parameters which conform to the scenarios with high vehicle velocities and large distances between roadside units(RSUs)that may be encountered in rural areas and on highways.展开更多
At present, the major drawback for mobile phones is the issue of power consumption. As one of the alternatives to decrease the power consumption of standard, power-hungry location-based services usually require the kn...At present, the major drawback for mobile phones is the issue of power consumption. As one of the alternatives to decrease the power consumption of standard, power-hungry location-based services usually require the knowledge of how individual phone features consume power. A typical phone feature is that the applications related to multimedia streaming utilize more power while receiving, processing, and displaying the multimedia contents, thus contributing to the increased power consumption. There is a growing concern that current battery modules have limited capability in fulfilling the long-term energy need for the progress on the mobile phone because of increasing power consumption during multimedia streaming processes. Considering this, in this paper, we provide an offline meaning sleep-mode method to compute the minimum power consumption comparing with the power-on solution to save power by implementing energy rate adaptation(RA) mechanism based on mobile excess energy level purpose to save battery power use. Our simulation results show that our RA method preserves efficient power while achieving better throughput compared with the mechanism without rate adaptation(WRA).展开更多
In order to realize the coexistence between the LTE system and the spectrum authorized systems over 700MHz frequency band,the geographical position and operation band location between long term evolution(LTE)base stat...In order to realize the coexistence between the LTE system and the spectrum authorized systems over 700MHz frequency band,the geographical position and operation band location between long term evolution(LTE)base stations and digital tevevision transmission tower should satisfy certain constraints,which are analyzed and deduced in this paper.Under the concluded constraints,the interference to each other is lower than their interference tolerances,so that the coexistance between the two types of systems is performed.Based on the constraints for both LTE and spectrum authorized systems,numerical results of the geographical position interval and operation band location interval are obtained,which have significant practical value for the LTE base station placement,network planning and operation band selection.展开更多
In order to solve the challenging coverage problem that the long term evolution（ LTE） networks are facing, a coverage optimization scheme by adjusting the antenna tilt angle（ ATA） of evolved Node B（ e NB） is pro...In order to solve the challenging coverage problem that the long term evolution（ LTE） networks are facing, a coverage optimization scheme by adjusting the antenna tilt angle（ ATA） of evolved Node B（ e NB） is proposed based on the modified particle swarm optimization（ MPSO） algorithm.The number of mobile stations（ MSs） served by e NBs, which is obtained based on the reference signal received power（RSRP） measured from the MS, is used as the metric for coverage optimization, and the coverage problem is optimized by maximizing the number of served MSs. In the MPSO algorithm, a swarm of particles known as the set of ATAs is available; the fitness function is defined as the total number of the served MSs; and the evolution velocity corresponds to the ATAs adjustment scale for each iteration cycle. Simulation results showthat compared with the fixed ATA, the number of served MSs by e NBs is significantly increased by 7. 2%, the quality of the received signal is considerably improved by 20 d Bm, and, particularly, the system throughput is also effectively increased by 55 Mbit / s.展开更多
Quality of experience （ QoE ） based scheduling algorithm of long term evalution （ LTE ） network with various traffics is studied. Utility functions are adopted to estimate mean opinion score （MOS） for different ...Quality of experience （ QoE ） based scheduling algorithm of long term evalution （ LTE ） network with various traffics is studied. Utility functions are adopted to estimate mean opinion score （MOS） for different traffics and a new MOS metric called normalized MOS is defined. A scheduling algorithm based on normalized MOS and greedy algorithm is proposed, aiming at maximizing the entirety MOS level of the whole users in the cell. We compare the performance of the proposed algorithm with other typical scheduling algorithms and the simulation results show that the algorithm pro- posed outperform other ones in term of QoE and fairness.展开更多
Radio resource management mechanisms in current and future wireless networks is expected to face an enormous challenge due to the ever increasing demand for bandwidth and latency sensitive applications on mobile devic...Radio resource management mechanisms in current and future wireless networks is expected to face an enormous challenge due to the ever increasing demand for bandwidth and latency sensitive applications on mobile devices.This is because an optimal resource allocation scheme which attempts to multiplex the available bandwidth in order to maximize Quality of service(QoS),will pose an exponential computational burden at eNodeB.In order to minimize such computational overhead,this work proposes a hybrid offline-online resource allocation strategy which effectively allocates all the available resources among flows such that their QoS requirements are satisfied.The flows are firstly classified into priority buckets based on real-time criticality factors.During the offline phase,the scheduler attempts to maintain the system load within a pre-specified safe threshold value by selecting an appropriate number of buckets.This offline selection procedure makes use of supervisory control theory of discrete event systems to synthesize an offline scheduler.Next,we have devised an online resource allocation strategy which runs on top of the offline policy and attempts to minimize the impact of the inherent variability in wireless networks.Simulation results show that the proposed scheduling framework is able to provide satisfactory QoS to all end users in most practical scenarios.展开更多
In the Long Term Evolution(LTE)downlink multicast scheduling,Base Station(BS)usually allocates transmit power equally among all Resource Blocks(RBs),it may cause the waste of transmit power.To avoid it,this paper put ...In the Long Term Evolution(LTE)downlink multicast scheduling,Base Station(BS)usually allocates transmit power equally among all Resource Blocks(RBs),it may cause the waste of transmit power.To avoid it,this paper put forward a new algorithm for LTE multicast downlink scheduling called the Energy-saving based Inter-group Proportional Fair(EIPF).The basic idea of EIPF is to calculate an appropriate transmitting power for each group according to its data rate respectively,and then follow the inter-group proportional fair principle to allocate RBs among multicast groups.The results of EIPF simulation show that the proposed algorithm not only can reduce the transmit power of BS effectively but also improve the utilization rate of energy.展开更多
本文针对目前算法处理多类别业务时低优先级业务带宽不足,影响整体服务质量(Quality of Service,QoS)的问题,提出用于多类别业务的新的调度算法,包括用于eNodeB的多类别业务调度算法和用于UE的多类别业务优先级调整算法。通过本文算法,...本文针对目前算法处理多类别业务时低优先级业务带宽不足,影响整体服务质量(Quality of Service,QoS)的问题,提出用于多类别业务的新的调度算法,包括用于eNodeB的多类别业务调度算法和用于UE的多类别业务优先级调整算法。通过本文算法,能保证紧急要求的UE总是被优先调度,能够最大化MAC层吞吐量,同时能满足最小QoS约束,并进一步改善低优先级业务的资源不足的问题。实验表明本文算法能显著改善LTE上行链路性能。展开更多
The introduction of new mobile services,mainly UMTS(Universal Mobile Telecommunications System)and LTE(Long Term Evolution),in the digital dividend portion of the UHF spectrum(from 790 MHz to 862 MHz),resulting from t...The introduction of new mobile services,mainly UMTS(Universal Mobile Telecommunications System)and LTE(Long Term Evolution),in the digital dividend portion of the UHF spectrum(from 790 MHz to 862 MHz),resulting from the digital switchover process,makes necessary the assessment of how much the interference of these signals impacts on QoS of existing DVB-T services,in particular when operating on adjacent bands.To this aim,in this paper an analysis of coexistence between broadcast television services and broadband mobile communication systems is carried out.It is based on the computation of specific parameters,such as the Protection Distance,evaluated in some specific operative scenarios.The goal of this analysis is to provide valuable inputs to operators,in deploying new mobile cellular networks in the above mentioned frequency band.展开更多
Time-interleaved structure can promote the equivalent processing speed of a digital signal processing system. An improved time-interleaved error feedback delta sigma modulator( TI-EF-DSM)for digital transmitter applic...Time-interleaved structure can promote the equivalent processing speed of a digital signal processing system. An improved time-interleaved error feedback delta sigma modulator( TI-EF-DSM)for digital transmitter application is presented in this paper. Two TI-EF-DSMs are compared,one is a conventional directly implemented and the other is the improved. The processing speed of the proposed two-channel improved time-interleaved error feedback delta sigma modulator( ITI-EF-DSM) is higher than the conventional directly implemented TI-EF-DSM for shortened critical path. A digital transmitter based on the ITI-EF-DSM is implemented on field progrmmable gate array( FPGA). The long term evolution( LTE) signals with different bandwidths of 5 MHz,10 MHz and 20 MHz are used as the signal source to evaluate the transmitter. The achieved SNR is 41 dB for the 20 MHz LTE signal with the processing clock of only 184 MHz.展开更多
A multiple-input multiple-output interleave division multiple access (MIMO-IDMA) system with Triple Polarized Division Multiplexing (TPDM) is presented in this paper. The present methodology replaces three indepe...A multiple-input multiple-output interleave division multiple access (MIMO-IDMA) system with Triple Polarized Division Multiplexing (TPDM) is presented in this paper. The present methodology replaces three independent linearly polarized antennas with a single triple polarized antenna at both the transmitter and receiver. The users in the communication link are accommodated and separated using a user-specific interleaver combined with low rate spreading sequence. To eliminate the effects of multi-stream interference (MSI), minimum mean square error (MMSE) algorithm based on successive interference cancellation (SIC) Multi-user detection (MUD) technique is employed at the receiver. Furthermore, log-maximum a posteriori probability (MAPP) decoding algorithm is implemented at the mobile stations (MSs) to overcome the effects of multi-user interference (MUI) effects. The paper also evaluates the effects of coded MIMO-IDMA in the downlink communication by adopting the Stanford University Interim (SUI) and Long-term Evolution (LTE)channel model specifications. In comparison with the traditional uncoded system, the present solution considering turbo coded triple-polarized MIMO-IDMA system with iterative decoding algorithm provides better bit error rate (BER) with reduced signal to noise ratio (SNR). The simulation results also show that though the SNR requirement is higher for the proposed technique compared to the conventional uni-polarized antenna based MIMO-IDMA system, it gives the advantages of achieving higher data rate with reduced cost and space requirements in the context of a downlink (DL).展开更多
A broadband class-F power amplifier for multiband LTE handsets applications is developed across 2.3- 2.7 GHz. The power amplifier maintains constant fundamental impedance at the output matching circuit which is operat...A broadband class-F power amplifier for multiband LTE handsets applications is developed across 2.3- 2.7 GHz. The power amplifier maintains constant fundamental impedance at the output matching circuit which is operating for broadband. The nearly zero of second harmonic impedance and nearly infinity of third harmonic impedance are found for highly efficient class-F PA. The harmonic control circuits are immersed into the broad- band output matching for fundamental frequency. For demonstration, the PA is implemented in InGaP/GaAs HBT process, and tested across the frequency range of 2.3-2.7 GHz using a long-term evolution signal. The presented PA delivers good performance of high efficiency and high linearity, which shows that the broadband class-F PA supports the multiband LTE handsets applications.展开更多
Because of the integration of long term evolution （LTE） technology and mobile satellite communication systems, uplink access technology for LTE-based geo-stationary earth orbit （GEO） satellite has become a popular...Because of the integration of long term evolution （LTE） technology and mobile satellite communication systems, uplink access technology for LTE-based geo-stationary earth orbit （GEO） satellite has become a popular research topic for satellite system. In order to solve the problem of unreasonable design for physical random access channel （PRACH） signal structure and reduce the effect of time uncertainty, this paper proposes a novel random access preamble based on time pre-compensation （TPC） for LTE-Satellite （LTE-S） system. In this scheme, by applying the method of non-linear least squares, the user terminal （UT） can use and based on the transmission delay the receiving power to estimate the communication round trip delay （RTD） of the beam center and the satellite, RTD can be compensated before transmission. Therefore, the preamble length and duration can be reduced without related to the maximum of RTD. In order to verify the performance of the scheme, the MATLAB is used to build a test system. The simulation results show that the proposed preamble satisfies the requirements of LTE-S system, and the better performance than previous researches is obtained.展开更多
In this study,we provide a detailed analysis of the frequency division duplex long term evolution downlink(FDD LTE DL)signal for passive bistatic radars that use the signal as an illuminator of opportunity.In particul...In this study,we provide a detailed analysis of the frequency division duplex long term evolution downlink(FDD LTE DL)signal for passive bistatic radars that use the signal as an illuminator of opportunity.In particular,we analyze the crossambiguity function and illustrate its undesired deterministic peaks in the Doppler dimension due to the specific structure of the FDD LTE DL signal.A new adaptive mismatched filtering method is proposed for pre-processing the original reference signal to suppress these undesired deterministic peaks in the range-Doppler processing.The effectiveness of our proposed method is demonstrated via simulations following robustness analysis,showing that all undesired peaks are suppressed below-40 dB,with only 1.7 dB reduction in the main peak.展开更多
This paper presents a high linearity downconverter implemented in a 0.18μm CMOS process for long term evolution（LTE） receivers without a surface acoustic wave（SAW） filter.The proposed downconverter is composed of...This paper presents a high linearity downconverter implemented in a 0.18μm CMOS process for long term evolution（LTE） receivers without a surface acoustic wave（SAW） filter.The proposed downconverter is composed of a transconductance（Gm） stage,a passive mixer,a current buffer,a transimpedance（TIA） stage,and a DC-offset cancellation（DCOC） loop.The current buffer is utilized to provide very low load impedance for the passive mixer at high frequencies and reduce the output voltage swing induced by out-of-band blockers.This technique improves the input referred third-order intercept point（IIP3） and second-order intercept point（IIP2） of the down-converter by 4.5 dB and 11 dB,respectively.The measured results show that the proposed downconverter achieves a voltage conversion gain of 29.5 dB,double sideband noise figure of 12.7 dB,out-of-band IIP3 of 13 dBm and IIP2 of more than 62 dBm.展开更多
文摘Vehicular ad hoc networks(VANETs)that use the IEEE 802.11p communication standard face a number of challenges,not least when it comes to safety messages on the VANET control channel(CCH)where short delay times and reliable delivery are of pri-mary importance.In this paper we propose a vehicular machine-to-machine(VM2M)overlay network that uses Long Term Evolu-tion(LTE)physical random access channel(PRACH)to emulate VANET CCH.The overlay network uses dedicated preambles to separate vehicular traffic from regular LTE traffic and a cartier sense multiple access with collision avoidance(CSMA-CA)layer similar to the one used in IEEE 802.15.4 to avoid the four step handshake and the overhead it incurs.The performance of the pro-posed overlay is evaluated under a wide range of PRACH parameters which conform to the scenarios with high vehicle velocities and large distances between roadside units(RSUs)that may be encountered in rural areas and on highways.
基金supported by X-Project funded by the Ministry of Science,ICT&Future Planning under Grant No.NRF-2015R1A2A1A16074929
文摘At present, the major drawback for mobile phones is the issue of power consumption. As one of the alternatives to decrease the power consumption of standard, power-hungry location-based services usually require the knowledge of how individual phone features consume power. A typical phone feature is that the applications related to multimedia streaming utilize more power while receiving, processing, and displaying the multimedia contents, thus contributing to the increased power consumption. There is a growing concern that current battery modules have limited capability in fulfilling the long-term energy need for the progress on the mobile phone because of increasing power consumption during multimedia streaming processes. Considering this, in this paper, we provide an offline meaning sleep-mode method to compute the minimum power consumption comparing with the power-on solution to save power by implementing energy rate adaptation(RA) mechanism based on mobile excess energy level purpose to save battery power use. Our simulation results show that our RA method preserves efficient power while achieving better throughput compared with the mechanism without rate adaptation(WRA).
基金Supported by the National High Technology Research and Development Program of China(No.2011AA01A105)the Key Deplogment Project of China Academic of Sciences(KGZD-EW-103)Shanghai Committee of Science and Technology(11DZ1500500)
文摘In order to realize the coexistence between the LTE system and the spectrum authorized systems over 700MHz frequency band,the geographical position and operation band location between long term evolution(LTE)base stations and digital tevevision transmission tower should satisfy certain constraints,which are analyzed and deduced in this paper.Under the concluded constraints,the interference to each other is lower than their interference tolerances,so that the coexistance between the two types of systems is performed.Based on the constraints for both LTE and spectrum authorized systems,numerical results of the geographical position interval and operation band location interval are obtained,which have significant practical value for the LTE base station placement,network planning and operation band selection.
基金The National High Technology Research and Development Program of China(863 Program)(No.2014AA01A702)the National Science and Technology Major Project(No.2013ZX03001032-004)+1 种基金the National Natural Science Foundation of China(No.6122100261201170)
文摘In order to solve the challenging coverage problem that the long term evolution（ LTE） networks are facing, a coverage optimization scheme by adjusting the antenna tilt angle（ ATA） of evolved Node B（ e NB） is proposed based on the modified particle swarm optimization（ MPSO） algorithm.The number of mobile stations（ MSs） served by e NBs, which is obtained based on the reference signal received power（RSRP） measured from the MS, is used as the metric for coverage optimization, and the coverage problem is optimized by maximizing the number of served MSs. In the MPSO algorithm, a swarm of particles known as the set of ATAs is available; the fitness function is defined as the total number of the served MSs; and the evolution velocity corresponds to the ATAs adjustment scale for each iteration cycle. Simulation results showthat compared with the fixed ATA, the number of served MSs by e NBs is significantly increased by 7. 2%, the quality of the received signal is considerably improved by 20 d Bm, and, particularly, the system throughput is also effectively increased by 55 Mbit / s.
基金Supported by China National S&T Major Project(2013ZX03003002-003)Beijing Natural Science Foundation(4152047)National High Technology Research and Development Program of China(863Program)(2014AA01A701)
文摘Quality of experience （ QoE ） based scheduling algorithm of long term evalution （ LTE ） network with various traffics is studied. Utility functions are adopted to estimate mean opinion score （MOS） for different traffics and a new MOS metric called normalized MOS is defined. A scheduling algorithm based on normalized MOS and greedy algorithm is proposed, aiming at maximizing the entirety MOS level of the whole users in the cell. We compare the performance of the proposed algorithm with other typical scheduling algorithms and the simulation results show that the algorithm pro- posed outperform other ones in term of QoE and fairness.
基金partially supported by TATA Consultancy Services(TCS),India,through TCS Research Fellowship Program
文摘Radio resource management mechanisms in current and future wireless networks is expected to face an enormous challenge due to the ever increasing demand for bandwidth and latency sensitive applications on mobile devices.This is because an optimal resource allocation scheme which attempts to multiplex the available bandwidth in order to maximize Quality of service(QoS),will pose an exponential computational burden at eNodeB.In order to minimize such computational overhead,this work proposes a hybrid offline-online resource allocation strategy which effectively allocates all the available resources among flows such that their QoS requirements are satisfied.The flows are firstly classified into priority buckets based on real-time criticality factors.During the offline phase,the scheduler attempts to maintain the system load within a pre-specified safe threshold value by selecting an appropriate number of buckets.This offline selection procedure makes use of supervisory control theory of discrete event systems to synthesize an offline scheduler.Next,we have devised an online resource allocation strategy which runs on top of the offline policy and attempts to minimize the impact of the inherent variability in wireless networks.Simulation results show that the proposed scheduling framework is able to provide satisfactory QoS to all end users in most practical scenarios.
基金Supported by the National Science and Technology Major Projects(2011ZX03005-004-03)Jiangsu University Natural Science Basic Research Project(10KJA510037)+3 种基金Nanjing University of Posts and Telecommunications (NJUPT)Introduction of Talent Project(NY209002)NJUPT Broadband Wireless Communication and Sensor Network Technology Key Laboratory of the Ministry of Education Research Fund Project(NYKL201108)Jiangsu Provincial Science and Technology Support Program of Industrial Projects(No.BE2013019)Jiangsu Construction Engineering College Dominant Disciplines Funded Projects(Information and Communication Engineering)
文摘In the Long Term Evolution(LTE)downlink multicast scheduling,Base Station(BS)usually allocates transmit power equally among all Resource Blocks(RBs),it may cause the waste of transmit power.To avoid it,this paper put forward a new algorithm for LTE multicast downlink scheduling called the Energy-saving based Inter-group Proportional Fair(EIPF).The basic idea of EIPF is to calculate an appropriate transmitting power for each group according to its data rate respectively,and then follow the inter-group proportional fair principle to allocate RBs among multicast groups.The results of EIPF simulation show that the proposed algorithm not only can reduce the transmit power of BS effectively but also improve the utilization rate of energy.
文摘本文针对目前算法处理多类别业务时低优先级业务带宽不足,影响整体服务质量(Quality of Service,QoS)的问题,提出用于多类别业务的新的调度算法,包括用于eNodeB的多类别业务调度算法和用于UE的多类别业务优先级调整算法。通过本文算法,能保证紧急要求的UE总是被优先调度,能够最大化MAC层吞吐量,同时能满足最小QoS约束,并进一步改善低优先级业务的资源不足的问题。实验表明本文算法能显著改善LTE上行链路性能。
文摘The introduction of new mobile services,mainly UMTS(Universal Mobile Telecommunications System)and LTE(Long Term Evolution),in the digital dividend portion of the UHF spectrum(from 790 MHz to 862 MHz),resulting from the digital switchover process,makes necessary the assessment of how much the interference of these signals impacts on QoS of existing DVB-T services,in particular when operating on adjacent bands.To this aim,in this paper an analysis of coexistence between broadcast television services and broadband mobile communication systems is carried out.It is based on the computation of specific parameters,such as the Protection Distance,evaluated in some specific operative scenarios.The goal of this analysis is to provide valuable inputs to operators,in deploying new mobile cellular networks in the above mentioned frequency band.
基金Supported by the National Natural Science Foundation of China(No.61674037)the National Key Research and Development Program of China(No.2016YFC0800400)+2 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe National Power Grid Corp Science and Technology Project(No.SGTYHT/16-JS-198)the State Grid Nanjing Power Supply Company Project(No.1701052)
文摘Time-interleaved structure can promote the equivalent processing speed of a digital signal processing system. An improved time-interleaved error feedback delta sigma modulator( TI-EF-DSM)for digital transmitter application is presented in this paper. Two TI-EF-DSMs are compared,one is a conventional directly implemented and the other is the improved. The processing speed of the proposed two-channel improved time-interleaved error feedback delta sigma modulator( ITI-EF-DSM) is higher than the conventional directly implemented TI-EF-DSM for shortened critical path. A digital transmitter based on the ITI-EF-DSM is implemented on field progrmmable gate array( FPGA). The long term evolution( LTE) signals with different bandwidths of 5 MHz,10 MHz and 20 MHz are used as the signal source to evaluate the transmitter. The achieved SNR is 41 dB for the 20 MHz LTE signal with the processing clock of only 184 MHz.
文摘A multiple-input multiple-output interleave division multiple access (MIMO-IDMA) system with Triple Polarized Division Multiplexing (TPDM) is presented in this paper. The present methodology replaces three independent linearly polarized antennas with a single triple polarized antenna at both the transmitter and receiver. The users in the communication link are accommodated and separated using a user-specific interleaver combined with low rate spreading sequence. To eliminate the effects of multi-stream interference (MSI), minimum mean square error (MMSE) algorithm based on successive interference cancellation (SIC) Multi-user detection (MUD) technique is employed at the receiver. Furthermore, log-maximum a posteriori probability (MAPP) decoding algorithm is implemented at the mobile stations (MSs) to overcome the effects of multi-user interference (MUI) effects. The paper also evaluates the effects of coded MIMO-IDMA in the downlink communication by adopting the Stanford University Interim (SUI) and Long-term Evolution (LTE)channel model specifications. In comparison with the traditional uncoded system, the present solution considering turbo coded triple-polarized MIMO-IDMA system with iterative decoding algorithm provides better bit error rate (BER) with reduced signal to noise ratio (SNR). The simulation results also show that though the SNR requirement is higher for the proposed technique compared to the conventional uni-polarized antenna based MIMO-IDMA system, it gives the advantages of achieving higher data rate with reduced cost and space requirements in the context of a downlink (DL).
基金supported by the National Natural Science Foundation of China(No.61404032)
文摘A broadband class-F power amplifier for multiband LTE handsets applications is developed across 2.3- 2.7 GHz. The power amplifier maintains constant fundamental impedance at the output matching circuit which is operating for broadband. The nearly zero of second harmonic impedance and nearly infinity of third harmonic impedance are found for highly efficient class-F PA. The harmonic control circuits are immersed into the broad- band output matching for fundamental frequency. For demonstration, the PA is implemented in InGaP/GaAs HBT process, and tested across the frequency range of 2.3-2.7 GHz using a long-term evolution signal. The presented PA delivers good performance of high efficiency and high linearity, which shows that the broadband class-F PA supports the multiband LTE handsets applications.
基金sponsored by the Science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory (ITD-U13007/KX132600014)the National Natural Science Foundation of China (91438114)the Fundamental Research Funds for the Central Universities (2014RC0202)
文摘Because of the integration of long term evolution （LTE） technology and mobile satellite communication systems, uplink access technology for LTE-based geo-stationary earth orbit （GEO） satellite has become a popular research topic for satellite system. In order to solve the problem of unreasonable design for physical random access channel （PRACH） signal structure and reduce the effect of time uncertainty, this paper proposes a novel random access preamble based on time pre-compensation （TPC） for LTE-Satellite （LTE-S） system. In this scheme, by applying the method of non-linear least squares, the user terminal （UT） can use and based on the transmission delay the receiving power to estimate the communication round trip delay （RTD） of the beam center and the satellite, RTD can be compensated before transmission. Therefore, the preamble length and duration can be reduced without related to the maximum of RTD. In order to verify the performance of the scheme, the MATLAB is used to build a test system. The simulation results show that the proposed preamble satisfies the requirements of LTE-S system, and the better performance than previous researches is obtained.
基金Project supported by the National Key Laboratory Fund(No.6142411183302)。
文摘In this study,we provide a detailed analysis of the frequency division duplex long term evolution downlink(FDD LTE DL)signal for passive bistatic radars that use the signal as an illuminator of opportunity.In particular,we analyze the crossambiguity function and illustrate its undesired deterministic peaks in the Doppler dimension due to the specific structure of the FDD LTE DL signal.A new adaptive mismatched filtering method is proposed for pre-processing the original reference signal to suppress these undesired deterministic peaks in the range-Doppler processing.The effectiveness of our proposed method is demonstrated via simulations following robustness analysis,showing that all undesired peaks are suppressed below-40 dB,with only 1.7 dB reduction in the main peak.
基金supported by the National High Technology Research and Development Program of China(No.2009AA011608)the National Major Science and Technology Projects Program of China(No.2009ZX03002-004-02)
文摘This paper presents a high linearity downconverter implemented in a 0.18μm CMOS process for long term evolution（LTE） receivers without a surface acoustic wave（SAW） filter.The proposed downconverter is composed of a transconductance（Gm） stage,a passive mixer,a current buffer,a transimpedance（TIA） stage,and a DC-offset cancellation（DCOC） loop.The current buffer is utilized to provide very low load impedance for the passive mixer at high frequencies and reduce the output voltage swing induced by out-of-band blockers.This technique improves the input referred third-order intercept point（IIP3） and second-order intercept point（IIP2） of the down-converter by 4.5 dB and 11 dB,respectively.The measured results show that the proposed downconverter achieves a voltage conversion gain of 29.5 dB,double sideband noise figure of 12.7 dB,out-of-band IIP3 of 13 dBm and IIP2 of more than 62 dBm.
