UEs Power Reduction Evolution with Adaptive Mechanism over LTE Wireless Networks

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).

Modified particle swarm optimization-based antenna tilt angle adjusting scheme for LTE coverage optimization

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.

LTE系统中多类别业务的调度算法研究

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。

Improved Method of Contention-Based Random Access in LTE System

Random access is the necessary process to establish the wireless link between the user equipment （UE） and network. The performance of the random access directly affects the performance of the network. In this work, we propose a method on the basis of the existing alternatives. In this method, we estimate the system load in advance to adjust the number of terminals. An access threshold is set to control the number of terminals which want to access the base station at an acceptable level. At the same time, we havean improvement on the existing power climbing strategy. We suppose that the power ramping is not always necessary for the re-access. And the selection ofpower ramping steps is studied in this paper. Simulations based on MATLAB are employed to evaluate the effectiveness of the proposed solution and to make comparisons with existing alternatives.

Parameter analysis for the coexistence of cognitive LTE and spectrum authorized systems

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.

Quality of experience based scheduling algorithm in LTE network with various traffics

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.

ENERGY-SAVING SCHEDULING FOR LTE MULTICAST SERVICES

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.

On Coexistence of Vehicular Overlay Network and H2H Terminals on PRACH in LTE

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.

INTERFERENCE COORDINATION METHOD BASED ON GRAPH THEORY IN TWO-TIER CELLULAR NETWORKS

This paper studies an interference coordination method by means of spectrum allocation in Long-Term Evolution (LTE) multi-cell scenario that comprises of macrocells and femtocells. The purpose is to maximize the total throughput of femtocells while ensuring the Signal-to-Interference plus Noise Ratio (SINR) of the edge macro mobile stations (mMSs) and the edge femtocell Mobile Stations (fMSs). A new spectrum allocation algorithm based on graph theory is proposed to reduce the interference. Firstly, the ratio of Resource Blocks (RBs) that mMSs occupy is obtained by genetic algorithm. Then, after considering the impact of the macro Base Stations (mBSs) and small scale fading to the fMS on different RBs, multi-interference graphs are established and the spectrum is allocated dynamically. The simulation results show that the proposed algorithm can meet the Quality of Service (QoS) requirements of the mMSs. It can strike a balance between the edge fMSs' throughput and the whole fMSs' throughput.

Multipath tracking with LTE signals for accurate TOA estimation in the application of indoor positioning

Indoor positioning with high accuracy plays an important role in different application scenar-ios.As a widely used mobile communication signal,the Long-Term Evolution(LTE)network can be well received in indoor and outdoor environments.This article studies a method of using different reference signals in the LTE downlink for carrier phase time of arrival(TOA)estimation.Specifically,a solution is proposed and a multipath tracking Software Defined Receiver(SDR)is developed for indoor positioning.With our SDR indoor positioning system,the pilot signals of the LTE signals are firstly obtained by the coarse synchronization and demodulation.Then,with the assistance of the pilot signals,the time delay acquisition,the multipath estimating delay lock loop(MEDLL)algorithm,and the multipath anomaly detection are sequentially carried out to obtain navigation observations of received signals.Furthermore,to compare the perfor-mance of different pilot signals,the Secondary Synchronous Signals(SSS)and Cell Reference Signals(CRS)are used as pilot signals for carrier phase-based TOA estimation,respectively.Finally,to quantify the accuracy of our multipath tracking SDR,indoor field tests are carried out in a conference environment,where an LTE base station is installed for commercial use.Our test results based on CRS show that,in the static test scenarios,the TOA accuracy measured by the 1-σerror interval is about 0.5 m,while in the mobile environment,the probability of range accuracy within 1.0 m is 95%.

Efficient Priority Packet Recovery Based on Network Coding in DVB-IPDC System

In DVB-IPDC system, due to the constraints of handheld devices and the broadcast nature of wireless network, packet loss is inevitable. ECDR-NC proposed is a retransmission encoding packet selection algorithm based on the dynamic information updating, which can find the current most effective complete decoding packet. ECDR-NC can not only avoid the redundant encoding packets due to the overlapping among encoding packets, but also reduce the computational complexity compared with the traditional encoding schemes. Furthermore, the retransmission upper bound of ECDR-NC is fully controlled. In time-sensitive applications, to maximize the aggregate number of recovery packets while minimizing the total number of discarded packets due to the time limit according to the priority preference, the adaptive priority scheme EPNC is formulized, and the weighted relation graph is constructed to find the maximum-weighted encoding packets sequence according to the decoding gains. In the same network environment, the performances comparisons between PNC and EPNC show that EPNC is more efficient and more rational, and the average discarded packets ratios ofEPNC can be reduced about 18%~27%. The main contributions of this paper are an effective retransmission encoding packet selection algorithm ECDR-NC proposed, and a new adaptive priority recovery scheme EPNC introduced into DVB-IPDC system.

Improved time-interleaved error feedback delta sigma modulator for digital transmitter application

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.

Triple-Polarized Multi-User Mimo-Idma System under Correlated Fading Channel

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).

Design of broadband class-F power amplifier for multiband LTE handsets applications

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.

Random access preamble design based on time pre-compensation for LTE-satellite system

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.

A high linearity downconverter for SAW-less LTE receivers

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.

Doppler ambiguity analysis and suppression for LTE-based passive bistatic radars

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.