# A Software Defined Radio Evaluation Platform for WBAN Systems
## 4 Implementation and Demonstration  
### Implementation Architecture of Proposed Evaluation Platform for WBAN Systems  
The proposed SDR evaluation platform is implemented on a MiniBEE4 platform provided by Canadian Microelectronics Cooperation (CMC), Kingston, ON, Canada. The MiniBEE4 contains a Xilinx Virtex-6-XC6 VSX475T FPGA, San Jose, CA, USA connected with a configurable FMC111/110 RF front-end and a personal computer with CentOS running in it. In addition, two isotropic antennas are attached to the RF front-end. At the same time, an Agilent Infiniium DSA80000B spectrum analyzer (Agilent, Santa Clara, CA, USA) is utilized to determine the frequency characteristics and verify the performance of the RF front-end, as shown in Figure 9.  
Figure 8: Implementation architecture of the proposed SDR platform. Figure 9: Demonstration of the proposed SDR evaluation platform for WBAN systems. The User Interface (UI), connected with the MiniBEE4 SDR Platform, identifies the information source and received data, while the stack (MAC layer) is running on the CPU of the Personal Computer (PC). The security scheme that contains an authentication module and encryption module is implemented in the FPGA, while the reconfigurable baseband processing module of the Physical layer (PHY) is also performed in the integrated Xilinx Virtex-6-XC6 VSX475T FPGA (Xilinx, Inc., San Jose, CA, USA). In terms of the configurations of the RF front-end found in the physical layer, a typical configuration of the RF channel is defined as shown in Table 4. Since the MiniBEE4 platform integrates a reconfigurable FMC111/110 RF front-end, all the required operation frequencies specified in the IEEE 802.15.6 standard are supported and can be reconfigured through the RF setup. Demonstration of Evaluating a Baseband Processing Module with a Security Scheme for WBAN Performed in the Proposed Design  
To further evaluate and verify the functionality of the proposed SDR evaluation platform for WBAN systems, a baseband processing module [7] with a security scheme [8] designed for WBAN has been implemented and evaluated in the proposed evaluation platform. Validating the RF channel functionality in various scenarios was the primary interest. In terms of the demonstration, to assess the modulation scheme, Figure 10 demonstrates the constellation map for four cases. To be more precise, initially, there is a short distance between the two antennas (1 m), and the constellation map from the receiver is shown as Figure 10a. It can be observed that the transmission quality could be guaranteed at a one-meter distance. Afterward, a longer distance between two antennas (2 m) was applied, and Figure 10b illustrates the constellation map for that scenario. In this case, even though the transmission quality seems not as good as that in Figure 10a, the bit error rate can be further improved by the BCH decoding methods. Moreover, in the circumstance of Figure 10c, a practical transmission link, where the maximum frequency offset between the transmitter and the receiver is specified in the standard (20 ppm), is considered. Last but not least, after the frequency offset correction, the constellation map is demonstrated in Figure 10d, which shows satisfying transmission performance. The overall transmission performance is expressed by the Bit Error Rate (BER) vs. Signal to Noise Ratio (SNR) for different modulation methods, as shown in the left side of Figure 11. In the left figure, the pink line which is mostly overlapped with the blue line is the hardware (HW) performance result running in the proposed evaluation platform. It illustrates that the HW performance matches the simulation results. In order to improve the performance of the communication in WBAN systems, multiple BCH decoding methods are applied to replace the original hard-decision (HD) decoder specified in the IEEE 802.15.6 standard.