Improved Channel Reciprocity for Secure Communication in Next Generation Wireless Systems

To secure the wireless connection between devices with low computational power has been a challenging problem due to heterogeneity in operating devices,device to device communication in Internet of Things(IoTs)and 5G wireless systems.Physical layer key generation(PLKG)tackles this secrecy problem by introducing private keys among two connecting devices through wireless medium.In this paper,relative calibration is used as a method to enhance channel reciprocity which in turn increases the performance of the key generation process.Channel reciprocity based key generation is emerged as better PLKG methodology to obtain secure wireless connection in IoTs and 5G systems.Circulant deconvolution is proposed as a promising technique for relative calibration to ensure channel reciprocity in comparison to existing techniques Total Least Square(TLS)and Structured Total Least Square(STLS).The proposed deconvolution technique replicates the performance of the STLS by exploiting the possibility of higher information reuse and its lesser computational complexity leads to less processing time in comparison to the STLS.The presented idea is validated by observing the relation between signalto-noise ratio(SNR)and the correlation coefficient of the corresponding channel measurements between communicating parties.

Antenna calibration using channel prediction for time-varying channels

Traditional antenna calibration methods for time division duplex （TDD） systems asSume that the flee-space channel remains the same during calibration, which is unreasonable under the high-speed rail and other time-varying channel scenarios, and will cause calibration error due to time variability. This paper proposes an antenna calibration method for time-varying channels. In the proposed method, the transceiver first sequentially sends a pilot signal to ob- tain equivalent do^vnlink and uplink channel responses. Then, by predicting the downlink （uplink） channel response fed back from the receiver using the channel prediction algorithm, the transmitter obtains the channel response correspond- ing to the channel response on uplink （downlink）. Finally, the transmitter calculates the transmission calibration factor through the prediction value. Compared with the traditional antenna calibration method, this method can improve the accuracy of the calibration factor. Simulation results show that the performance degradation of antenna calibration can be caused by time-varying channels and the proposed method can well compensate for the performance loss and sig- nificantly improve the antenna calibration performance for time-varying channels.

一种新颖的TD-LTE系统上行小区间干扰管理方法(英文)

For OFDM based system with Single-Frequency Networking(SFN) ,ICI(inter-cell interference) ,especially uplink ICI,becomes a bottleneck to improve system performance. Since the conventional interference management scheme with OI(overload indicator) can not show the instantaneous ICI,this paper proposes a method to reduce ICI by utilizing channel reciprocity of TD-LTE system. In the proposed scheme,UE shall make a decision whether to reduce its power or not after predicting the instantaneous ICI level according to the scheduling results. The system simulation results show that the proposed scheme can reduce the uplink ICI effectively and improve the system performance such as system spectrum efficiency,10% user throughput,50% user throughput,packet drop rate etc. significantly while keep 5% cell edge user throughput loss less than 5%. For example,the proposed scheme improved system spectrum efficiency about 50% and 50% user throughput gain is larger than 140%. Meanwhile,the proposed scheme controls the system ICI level and variance effectively. The mean system ICI level and variance are reduced by 4.5dB and 18dB respectively. The proposed scheme can be joint implemented with those existing ICI mitigation methods such as(soft) frequency reuse,power control etc. to further improve the system performance.

Secure transmission technology based on direct modulation with random channel characteristics

Aiming at the problem of insufficient security in the existing wireless data trans-mission,a security transmission technology based on direct modulation with random channel characteristics is proposed.The method first estimates channel characteristics using the preamble in the communication frame,and then embeds channel characteristics into the I/Q modulator.After that,the modulated constellation diagram undergoes random hopping of the constellation position compared with the original constellation diagram,thus achieving the effect of secure transmission.Due to the reciprocity of the uplink and downlink channels,channel characteristics estimated by the downlink receiver are almost the same as those esti-mated by the uplink receiver,and the correct plaintext data can be recovered by performing corresponding demodulation with them.Compared with the existing scheme of quantizing channel characteristics and then encrypting data,the method reduces the performance loss caused by quantization.In addition,its bit error rate is lower than that of the quantization method.In general,it has higher security and convenience.

Secure transmission technology based on direct modulation with random channel characteristics

Aiming at the problem of insucient security in the existing wireless data trans-mission,a security transmission technology based on direct modulation with random channel characteristics is proposed.The method rst estimates channel characteristics using the preamble in the communication frame,and then embeds channel characteristics into the I/Q modulator.After that,the modulated constellation diagram undergoes random hopping of the constellation position compared with the original constellation diagram,thus achieving the e ect of secure transmission.Due to the reciprocity of the uplink and downlink channels,channel characteristics estimated by the downlink receiver are almost the same as those esti-mated by the uplink receiver,and the correct plaintext data can be recovered by performing corresponding demodulation with them.Compared with the existing scheme of quantizing channel characteristics and then encrypting data,the method reduces the performance loss caused by quantization.In addition,its bit error rate is lower than that of the quantization method.In general,it has higher security and convenience.

A High Consistency Wireless Key Generation Scheme for Vehicular Communication Based on Wiener Filter Extrapolation

Secret key generation from wireless channel is an emerging technology for communication network security,which exploits the reciprocity and time variability of wireless channels to generate symmetrical keys between the communication parties.Compared to the existing asymmetric key distribution methods,secret key generation from wireless channel has low complexity and high security,making it especially suitable for distributed networks.In vehicular communications,the reciprocity of wireless channel is degraded due to the movement of vehicular.This paper proposes a high consistency wireless key generation scheme for vehicular communication,especially applied to LTE-V2X(LTE vehicle to everything)systems.A channel reciprocity enhancement method is designed based on Wiener filter extrapolation,which can efficiently reduce the mismatch between the channels at the receiver and significantly reduce key disagreement rate.A real experimental system based on vehicle and universal software radio peripheral(USRP)platform is setup to verify the secret key generation in LTE-V2X systems.The effectiveness of the proposed method is verified in simulations and extensive practical tests.