Sigit Puspito Wigati Jarot

Experimental implementation of dynamic spectrum access for video transmission using USRP

In this paper we present the experimental implementation of dynamic spectrum access (DSA) algorithm using universal software radio peripheral (USRP) and GNU Radio. The setup contains two primary users and two cognitive radios or secondary users. One primary user is fixed and the other is allowed to change its position randomly. Depending upon the position of the primary user the cognitive user will use the spectrum band where the detected energy is below certain predefined threshold level. The cognitive radio users are also programmed to operate independently without interfering with each other using energy detection algorithm for spectrum sensing. The modulation scheme is set to GMSK for secondary user performing data transmission. This experimental setup is used to analyze the quality of video transmission using DSA which provides the insight regarding the possibility of using free spectrum space to improve the performance of the system and its advantage over a non-DSA system. From the experiment it is shown that under congestion and interference DSA perform better than a non- DSA system.

Collision probability of one-to-many reversible mapping for IPv6 address generation

The paper presents results of collision probability evaluation of a one-to-many reversible mapping between user space and IPv6 address space which is developed to improve of IPv6 addresses generation in a local area network (LAN). Each time a user accesses the network, a dynamic unicast IPv6 address is given via DHCPv6 (Dynamic Host Configuration Protocol for IPv6) server to protect users from unwanted behavior analysis exploiting IPv6 addresses, thus protecting user privacy. This IPv6 address is generated dynamically using CFB (Cipher Feedback) mode of AES (Advanced Encryption Standard) algorithm based on user identity. The dynamic address can be uniquely linked to user if the need arises to allow network administrator to identify user based on captured IPv6 address during any security event. Checksum has been used for validation of probability of coincidental match of randomly generated Interface Id or generated by some other mechanism. The collision probability of the one-to-many reversible mapping for stateful IPv6 address assignment is evaluated using birthday paradox. The results show that the collision probability is very small indeed. The one-to-many reversible mechanism may be incorporated as an extension to the current DHCPv6 software.

Wireless physical layer security using encryption and channel pre-compensation

In this paper we propose a scheme that provides physical layer security by combining two techniques known as encryption and channel pre-compensation. Encryption transforms the original signal constellation into a higher order constellation based on the key sequence generated by AES in counter-mode. Channel pre-compensation is performed based on the knowledge of channel, which is location specific, at the transmitter. These two techniques distort the original signal constellation which can only be recovered by the intended receiver. The proposed scheme not only makes the estimation of the constellation difficult but also the type of modulation that is used for the adversary. BER (bit error rate) is used as performance metric. We find that the adversary suffers from high BER as compared to the legitimate user; hence providing secure communication.

Wireless physical layer security using channel state information

In this paper we consider the problem of secure communication between two nodes, over a fading wireless medium, in the presence of a passive eavesdropper. We propose a scheme that provides security based on transforming the basic signal constellation to a higher order signal constellation with the help of conventional encryption method and then using channel knowledge (i.e. amplitude and phase variation), which is location specific, to distort the constellation of encrypted data. This scheme not only makes the estimation of the constellation difficult but also the type of modulation that is used for the adversary. BER (bit error rate) is used as performance metric. We find that the adversary suffers from high BER as compared to its legitimate counterpart.