This study presents a testbed for the emergency call (eCall) system satisfying the 3GPP TS 26.267/268/269 standard. Experiments are performed with the in‐vehicle system testbed in a laboratory or a car travelling in city, suburb, countryside or freeway. Sufficient data of the emergency communication signal is recorded and processed. Fading statistics of the received signal after power control are found and discussed with cumulative distribution function of the received signal power, level crossing rate and average fade duration. It is found that with probability less or equal to , fading and attenuation can vary from dB for the continuous wave (CW) signal at 500 Hz to dB for the CW signal at 2000 Hz. It is recommended to move the CW signals at 500 and 800 Hz for detection and synchronisation in the 3GPP standard to be at 1500 and 2000 Hz, respectively. This will give 9.5 dB improvement in detection and synchronisation. The longest fade duration observed is 540 ms. The 64 ms synchronisation signal in the current standard is insufficient to handle the fading. It is shown that fading is minimised in the frequency range [1000, 2500] Hz for the 3GPP TS 26.267 system.

One benefit of data communication over the voice channel of the cellular network is to reliably transmit real-time high priority data in case of life critical situations. An important implementation of this use-case is the pan-European eCall automotive standard, which is scheduled for deployment in 2018. The eCall in-band modem transmits emergency information from the in-vehicle system (IVS) over the global system for mobile communication (GSM) voice channel to the public safety answering point (PSAP) in case of a collision. The GSM voice channel is characterized by the non-linear vocoder which is designed to compress speech waveforms. The in-band modem encodes the emergency data using Turbo codes and then modulates the data into waveforms to securely and reliably transmit the information over the GSM vocoder. Thus, this paper evaluates the performance of the eCall in-band modem by simulating the coded bit error rate (BER) through the additive white Gaussian noise (AWGN) and the GSM adaptive multi-rate (AMR) vocoder using Turbo codes. Performance results are presented using different AMR bit rates.

The European Union (EU) emergency call (eCall) employs the GSM voice channel for vehicle emergency data transmission. However, fading statistics of the GSM voice channel after power control has not been discussed previously. This paper reports the power measurements for the end-to-end GSM voice channel with an in-vehicle system (IVS) transmitter in laboratory or on freeway. The data reveals that strong fading still exists in the GSMvoice channel after power control, which can cause severe packet loss and delay in the emergency call.

Data communications through the voice channel of the cellular network are important for telematics applications such as automatic vehicle crash notification, an implementation of which is the pan-European eCall system scheduled for deployment in 2015. The cellular voice channel includes the vocoder which is designed for compressing speech waveforms and is a hindrance for data communications. No mathematical model exists for the vocoder as a data communications channel. Thus, in this paper, the uncoded bit error rate (BER) is found by simulation using the bit-exact C-code implementation of the vocoder. The adaptive multi-rate (AMR) vocoder is used in GSM, the network on which eCall runs, and is the one used in these simulations. The BER is first presented for the vocoder-only channel at different AMR compression rates. Then it is presented for the vocoder and additive white Gaussian noise (AWGN) channel. Finally, an attempt is made to find the optimum receiver filter for the vocoder channel.

Data communications through the voice channel of the cellular network are important for telematics applications such as automatic vehicle crash notification, an implementation of which is the pan- European eCall system scheduled for deployment in 2015. The cellular voice channel includes the vocoder which is designed for compressing speech waveforms and is a hindrance for data communications. No mathematical model exists for the vocoder as a data communications channel. Thus, in this paper, the uncoded bit error rate (BER) is found by simulation using the bit-exact C- code implementation of the vocoder. The adaptive multi-rate (AMR) vocoder is used in GSM, the network on which eCall runs and is the one used in these simulations. The uncoded BER is presented for different compression rates along with other effects of the vocoder such as a wake-up effect and the signal-to-distortion ratio.

Performance of signal detection for intensity modulated direct detection optical communications systems through the turbulent atmosphere is studied considering statistics of photoelectron count in p-i-n photodiodes. The effect of atmospheric turbulence is modeled as a lognormal process. In this system, the photoelectron count is a conditional Poisson process, where the mean count is lognormal. A normal approximation is derived for this conditional Poisson process, which results in a simple calculation for the probability of miss. The probabilities of miss for quantum-limited detection and detection in the presence of thermal electronic noise are simulated and compared with calculations using the normal approximation. Simulation results match the analytical results. For the thermal noise case, the probability of miss is compared with the probability of false alarm to determine appropriate signal length and detection threshold settings for a required performance. Applying results in this paper, a system designer can determine appropriate signal length and detection threshold settings.

The probability of a miss in the detection of a signal in an optical communications system through the turbulent atmosphere using intensity modulation is studied. The turbulence of the atmosphere causes scintillation of the received signal intensity which is treated as a lognormal random process. The received background radiation and electronic noise in the receiver is treated as additive white Gaussian noise (AWGN). A Chernoff bound is derived for the lognormal sum distribution. An approximation for the lognormal sum distribution is investigated for its utility in calculating the probability of miss. For practical values of the signal-to-noise power ratio (SNR), a series solution for the characteristic function of the lognormal random variable is used to find the probability of miss. Simulation results agree with theoretical results. The method developed in this paper can be used by the system designer to choose the proper signal length and meet the system specifications for signal detection.

The probability of a miss in the detection of a signal in an optical communications system through the turbulent atmosphere using intensity modulation is studied. The turbulence of the atmosphere causes scintillation of the received signal intensity which is treated as a lognormal random process. The received background radiation and electronic noise in the receiver is treated as additive white Gaussian noise (AWGN). A Chernoff bound is derived. For practical values of the signal-to-noise power ratio (SNR), a series solution for the characteristic function of the lognormal random variable is used to find the probability of miss. Simulation results agree with theoretical results. The method developed in this paper can be used by the system designer to choose the proper signal length and meet the system specifications for signal detection.

This paper studies optical communications using subcarrier phase shift keying (PSK) intensity modulation through atmospheric turbulence channels. The bit error rate (BER) is derived for optical communication systems employing either on/off key (OOK) or subcarrier PSK intensity modulation. It is shown that at${\hbox{BER}} =10^{-6}$and a scintillation level of$\sigma = 0.1$, an optical communication system employing subcarrier BPSK is 3 dB better than a comparable system using fixed-threshold OOK. When$\sigma =0.2$, an optical communication system employing subcarrier BPSK achieves a${\hbox{BER}} = 10^{-6}$at${\hbox{SNR}} = 13.7$dB, while the BER of a comparable system employing OOK can never be less than$10^{-4}$. Convolutional codes are discussed for optical communication through atmospheric turbulence channels. Interleaving is employed to overcome memory effect in atmospheric turbulence channels. An upper bound on BER is derived for optical communication systems employing convolutional codes and subcarrier BPSK modulation.

In this correspondence, new binary sequence families Fkof period 2n-1 are constructed for even n and any k with gcd(k,n)=2 if n/2 is odd or gcd(k,n)=1 if n/2 is even. The distribution of their correlation values is completely determined. These families have maximum correlation 2n/2+1and family size 23n/2+ 2n/2for odd n/2 or 23n/2+2n/2-1 for even n/2. The proposed families include the large set of Kasami sequences, where the k is taken as k=n/2+1.