1. Date of download: 6/3/2016 Copyright © 2016 SPIE. All rights reserved. Principle of WDM-RoF system with optical virtual private network for inter-BSs and intra-BSs VPN. Figure Legend: From: Enabled scalable and privacy wavelength division multiplexing-radio over fiber system based on optical virtual private networks Opt. Eng. 2014;53(6):066105. doi:10.1117/1.OE.53.6.066105

2. Date of download: 6/3/2016 Copyright © 2016 SPIE. All rights reserved. Setup of the proposed WDM-RoF system with optical virtual private network for inter-BSs and intra-BSs. Figure Legend: From: Enabled scalable and privacy wavelength division multiplexing-radio over fiber system based on optical virtual private networks Opt. Eng. 2014;53(6):066105. doi:10.1117/1.OE.53.6.066105

3. Date of download: 6/3/2016 Copyright © 2016 SPIE. All rights reserved. The corresponding spectra of the proposed WDM-RoF system with virtual private network for inter-BSs and intra-BSs: (a) T×1 output signals, (b) two third-order sidebands with a frequency interval of 60 GHz, (c) combination of the US signal and the SSB VPN signal, (d) the reflected inter-BSs VPN signal with a 58-GHz frequency interval, (e) SOA input signals, (f) SOA output signals, (g) the inter-BSs VPN signal with a 58-GHz frequency interval, (h) 58 and 60-GHz MMW signals. Figure Legend: From: Enabled scalable and privacy wavelength division multiplexing-radio over fiber system based on optical virtual private networks Opt. Eng. 2014;53(6):066105. doi:10.1117/1.OE.53.6.066105

4. Date of download: 6/3/2016 Copyright © 2016 SPIE. All rights reserved. BER and eye diagrams. (a) US, (b) DS, (c) intra-BSs VPN, (d) inter-BSs VPN. Figure Legend: From: Enabled scalable and privacy wavelength division multiplexing-radio over fiber system based on optical virtual private networks Opt. Eng. 2014;53(6):066105. doi:10.1117/1.OE.53.6.066105

5. Date of download: 6/3/2016 Copyright © 2016 SPIE. All rights reserved. BER versus OSNR of inter-BSs VPN transmission at different data rates. Figure Legend: From: Enabled scalable and privacy wavelength division multiplexing-radio over fiber system based on optical virtual private networks Opt. Eng. 2014;53(6):066105. doi:10.1117/1.OE.53.6.066105

6. Date of download: 6/3/2016 Copyright © 2016 SPIE. All rights reserved. (a) BER and eye diagrams for inter-BSs VPN at λ2, λ4, λ6, and λ8, (b) received sensitivity and power penalty of inter-BSs VPN signal on i’th (i=1,2…8) channel versus channel number of inter-BSs VPN carriers. Figure Legend: From: Enabled scalable and privacy wavelength division multiplexing-radio over fiber system based on optical virtual private networks Opt. Eng. 2014;53(6):066105. doi:10.1117/1.OE.53.6.066105