# Ultra-Low-Power Wide Range Backscatter Communication Using Cellular Generated Carrier +
## 4 System Design and Simulation Configuration
### General System Parameters  
We recall that the aim is to investigate the feasibility of AmBC in a real world urban environment. Therefore, we model the simulation environment using realistic parameters and assumptions that reflect a practical AmBC system in order to acquire rational and practical results. The performance metrics considered for the analysis are the received power at the BD, the received power at the Rx, the time required for harvesting the energy at BD, and the outage ratio. Cellular antennas act as a source of the ambient signal, while the propagation between BD and Rx defines the coverage and outage of the service. The parameters applied in the simulations are listed in Table 3. Table 2 provides the parameters of the transmit antenna radiation pattern model, where a 0 dBi antenna gain is assumed for the BD in the forward and backscatter link, and also for the Rx antenna. The target of this study is to cover the existing cellular frequencies and the candidate frequency bands for IoT networks. Here, it must be noted that 900 MHz band is mainly used by cellular systems, and a large number of existing cellular sites use this band for providing basic cellular coverage. In Europe, the 700 MHz spectrum is available for digital television broadcasting [53], and is also considered to be a potential band for deploying 5G of cellular system [54]. Currently, in some European countries there is a debate going on about the usage of 200 MHz and different proposals are given, and the use of IoT at 200 MHz is one of them. The 500 MHz is considered to be an intermediate band between 200 and 700 MHz band. Therefore, for the research work of article, the simulations are performed at four different frequencies i.e., at 200 MHz, 500 MHz, 700 MHz, and 900 MHz. For indoor BDs, the results are presented with low and high BPL models and a in mixed type indoor environment. A fixed transmit power of 43 dBm is assumed for all macro cells in the network. We follow the reference [19], where, for bi-static dislocated type of backscatter communication with 5% outage probability and Rician factor \(K=3\) dB, the recommended fast fading margins are 10 dB and 5 dB for the forward and backscatter link, respectively. Similarly, for the forward link, a 7 dB slow fading margin is considered, and for the backward link the slow fading margins are selected following the recommendations given for the ITU D2D outdoor PL model and 3 GPP InH model in [50; 51], respectively. It is assumed that the polarization of the RF signal is not known; therefore, a polarization mismatch loss of 3 dB is considered in the forward link as well as in the backscatter link separately. A maximum power transfer is assumed, i.e., transmission co-efficient at BD is 1, and a 6 dB modulation loss factor at BD is also included in our computation. The receiver sensitivities of long range (LoRa) backscatter [55], narrow band-IoT (NB-IoT) [14], and Bluetooth low energy 5 (BLE 5) [16] technology are defined as -149, -141, and -97 dBm, respectively, as shown in Table 4. Backscatter devices can operate in a passive mode or in a semi-passive mode. It is reported in the reference [55] that a LoRa backscatter device requires 9.25 uW power for operation, and it can harvest the required energy from the dedicated or ambient source. The power consumption for NB-IoT and BLE 5 devices are 543 mW and 20 mW, respectively, and they typically admit a battery source for powering up the BD. In the case of BLE 4.0 compatible BLE-backscatter devices, the power consumption is improved to 1.55 mW, whereas the maximum data rate is limited to 1 Mbps with \(-92\) dBm sensitivity level [56]. However, here, it must be noted that we have only focused on BLE 5 in this article. The sensitivity level, power consumption, and the maximum supported data rates of different IoT technologies that are considered in this article are given in Table 4.