Adaptive physical layer security using code bank of sequences for CDMA

Wireless security is an important concern in todays technological world. Wireless devices are used to access data and private applications. From broadband to Wi-Fi, 3G to LTE Advanced, WiMAX to satellite communication every network demands on-the-air security from attacks. Tapping or Jamming attacks leak the secret data, while Service Disruption Attacks affecting QoS (Quality of Service) are relatively easy to perform. In CDMA, the channel and antenna dependent attacks are quite critical to avoid because of its wide bandwidth usage. The critical exchange of time and frequency parameters makes the physical layer elements vulnerable to security related attacks. In order to enable data security and secrecy, there is need of signal protection at the physical layer of CDMA system. Gold codes, M-sequences, OVSF and De-Bruijn sequences were used individually in wireless systems for scrambling purposes in previous proposals. These codes have their own advantages and disadvantages, when channel bandwidth and noise conditions change. This paper proposes a system which would select scrambling codes from a bank of all these mentioned codes depending upon the Signal to Noise Ratio (SNR) or Channel State Information (CSI). This code bank technique is shown as a highly practical solution in selection of proper code for mitigation of attacks and hence, to provide security at the physical layer of CDMA.