The rapid pace at which the technological innovations are being introduced in the world poses a potential challenge to the retailer, supplier, and enterprises. In the field of Infor- mation Technology (IT) there is a rapid growth in the last 30 years (Want 2006; Landt 2005). One of the most promising technological innovations in IT is radio frequency iden- tification (RFID) (Dutta et al. 2007; Whitaker et al. 2007; Bottani et al. 2009). The RFID technology was evolved in 1945 as an espionage tool invented by Leon Theremin for the Soviet Government (Nikitin et al. 2013, Tedjini et al. 2012). At that time it was mainly used by the military. The progress in microchip design, antenna technology and radiospreadspectrum pushed it into various applications like supply chain management, retail, auto- matic toll collection by tunnel companies, animal tracking, ski lift access, tracking library books, theft prevention, vehicle immobilizer systems, railway rolling stock identification, movement tracking, security, healthcare, printing, textiles and clothing (Weinstein 2005; Liu and Miao 2006; Rao et al. 2005; Wu et al. 2009; Tan 2008). RFID can make the compa- nies more competitive by changing the related processes in supply chain, manufacturing and retailing.
3. Radio & spreadspectrum technologies :– Wireless local area networks use a high-frequency radiotechnology similar to digital cellular & a low-frequency radiotechnology. Wireless LANs use spreadspectrumtechnology to enable communication between multiple devices in a limited area. IEEE 802.11 defines a common flavor of open-standards wireless radio-wave technology known as Wifi.
Although there are many schemes in the physical layer authentication, the most used RF watermarking scheme is spreadspectrum watermarking, since the spreadspectrum watermarking has been used in the ATSC Synchronization Standard for Distributed Transmission . Spreadspectrum watermarking is an important branch of the digital water- marking technology, whose core idea is hiding a watermark bit into carrier symbols to hide the watermark signal accord- ing to the theory of spreadspectrum communication . Most studies on spreadspectrum watermarking focused on watermarking multimedia data and minimizing the distortion at the receiver in terms of human perception , . The channel capacity of the spreadspectrum in the RF signals remains lacking in research. Compared with the traditional digital watermark, the challenge is the distortion definition for the digital carrier signal. The traditional distortion def- inition is designed for analog signals, which measures the waveform changes, but the transmitted information in digital communication is the digital symbol. We are concerned about the BER of the digital symbol, not the waveform changes. Therefore, the distortion should be redefined, and the analysis conclusion is different from that of the available literature. This paper has two main contributions: the redefinition of the distortion for the RF watermark, which is different from the available definition for the multimedia watermark, and the expression of the channel capacity and optimal parameters to achieve the maximal channel capacity.
Dr B. Siva Kumar Reddy, is currently working as an Associate Professor, Department of Electronics and Communication Engineering, CMR Engineering College, Hyderabad, India. He had received B.Tech (Electronics and Communication Engineering) and M.Tech (Very Large Scale Integrated Circuits Design) degrees from Jawaharlal Nehru Technological University, Hyderabad (JNTUH), PhD in the field of Wireless Communication from National Institute of Technology, Warangal, India, in 2009, 2012 and 2016, respectively. His area of research includes Multi Carrier Modulations, OFDM, internet of Things (IoT), PAPR Reduction techniques, Spectral leakages, Adaptive Modulation and Coding, Spectrum Sensing, Channel Estimation/Equalization/Synchronization, 3GPP, WiMAX, LTE, Performance analysis of sensors, Embedded sytems and Software Defined Radio. He is an ISTE (Indian Society for Technical Education) life time member and invited member of IDES (Institute of Doctors, Engineers and Scientists).
Under the pressure of the telecommunications require- ments, in 4G and much more in 5G , radios must be equipped with high performance systems that could ac- quire and use all available information about the channel . Here we focus on Direction of Arrival (DOA), esti- mation. The system is assumed to be implemented in every carrier of the multicarrier spreadspectrum system . Both spreadspectrumtechnology and the informa- tion of the reference/pilot bits are employed. Indeed, af- ter the code word dispreading of the array’s output vec- tor, the pilot signal is used to perform the second dis- preading. The resulted vector is used as the weight vector of the array. The produced power in the far field is writ- ten in quadratic form and its average is computed. The maximum of the produced beam is the DOAs estimate. In the current work, the functionality of the proposed system is addressed and its performance is, both analyti- cally and numerically, verified. In fact, after the Prob- ability Distribution Function (PDF) of the estimator is extracted, its potential to cope with very large number of interferers exhibiting fine resolution is demonstrated.
In this paper, the comparative study of three main Anti-jamming Techniques, viz, UDSSS, UFHSS and RD-DSSS are compared. These techniques are basically dependent on coordinated SS in case of spreading the message but differ in the method of choosing the communication channels. The techniques exhibit different properties against different jammers, i.e., RD-DSSS deals effectively against reactive jamming attacks. . DC- DSSS is the extension to traditional SS with additional encoding of the barker code. The other techniques like ZPK-DSSS  tells the concept like intractable forward decoding and efficient backward decoding along with key scheduling method. Baird et al. in  represented BBC algorithm for achieving the same level of jamming resistance as traditional spreadspectrum, at under half the bit rate with no shared keys. These are the contemporary Anti-jamming Techniques.
3.2 FREQUENCY HOPPING SPREADSPECTRUM: FH is the type of SS in which the carrier hops randomly form one frequency to another. A common modulation format for FH system is of M-ary frequency shift keying (MFSK). The combination of these two techniques is referred to simply as FH/MFSK. In this type of SS , the use of PN sequence is to modulate a phase shift keyed signal to achieve instantaneous spreading of the transmission bandwidth. The ability of such a system to combat the effects of jammers is determined by the processing gain of the system, which is a function of the PN sequence period. Two basic characterizations of frequency hopping:-
Most of the access technologies of the SUs that have been developed recently either focus on spectrum utilization by exploiting the spectrum holes or on the coexistence be- tween secondary and primary users which in turns classifies the cognitive radio networks into three broad categories: Interweave, overlay and underlay networks . In Interweave networks; secondary users can only access the spectrum when the PU is absent, and they should immediately vacate the channel once the PU resumes its operation. Underlay net- works are those that allow coexistence between primary and secondary users while satisfy- ing a predefined threshold called interference temperature which is determined by the FCC. Different from underlay model, overlay networks allow the primary and secondary users to transmit simultaneously in the same band by taking advantage of the coding strategies and the knowledge of the primary user’s message to eliminate the interference between the SUs and the PU . Interweave network is the most favored in practical implementations among the three paradigms due to its simple application and capability to adhere to the FCC requirements by efficiently utilizing the heavily equipped bands without interfering with the PU.
Spectrum is a group of electromagnetic radiations used for wireless communications. Chunks of these different ranges of frequencies are allocated for different applications for dedicated, successful and secure service provisioning. Different spectrum bands are allocated for different services and applications in order to guarantee interference free operation of the users. But, fixed allocation of the spectrum bands has created poor utilization scenario of allocated bands that has resulted in wastage of valuable natural resource. With the increase in wireless applications and its users, the service providers have been at loggerhead with each other for acquiring more spectrum. The regulatory agencies have faced a tough time for spectrum distribution especially during past one decade. Every nation has its right for unbounded use of the spectrum. At the international level, International Telecommunication Union (ITU) has been assigned the responsibility of allocation of spectrum for various countries in world radio communication conference. Considering the difficulties in spectrum allocation, authorities like Federal Communications Commission (FCC), Telecom Regulatory Authority of India (TRAI) emphasizes the need for change in spectrum regulatory policy from fixed to dynamic spectrum allocation.
In this paper, author presented a novel approach for watermarking of multimedia data and proposed a two dimensional spreadspectrum model which uses chipping sequence for encryption of input data. Chipping sequence is basically combination of bits which can be X-OR with the input data to produce encrypted data. Finally, at the receiver end, encrypted data is again X-OR with chipping sequence to generate original data . Here, author presented log 2 spatial domain method for spreadspectrum watermarking in which they used low intensity and mid intensity reasons for embedding the watermark information. They perform this experiment on various standard JPG images and trends a very good accuracy while decryption .
In , the necessity of using spectrum sensing techniques in a home base station is described. In  , it is proposed to use cognitive radiotechnology to manage spectrum resources to suppress the same layer interference between Macrocell and Femtocell two-tier heterogeneous networks, using dirty paper coding techniques and game theory to eliminate Interference with the same layer, but the spectrum detection efficiency is not high. In , the author investigates the problem of resource management in the Femtocell system under orthogonal frequency division multiplexing, and proposes a location-based allocation scheme between the macrocell and the Femtocell to accommodate the number of users. In , a two-threshold spectral sensing method is proposed, which uses two thresholds to judge the signal energy. However, when the energy is between the two thresholds, it does not participate in the final decision. Although the algorithm is also a certain degree Solved the problem of interference, but ignored some useful sense of information. In , it is proposed that the reliability of each perceptual user is different, so it is not appropriate to distribute the feedback channel evenly to each user.
would seem reasonable that the CTVR Executive, on receipt of the license give authority for administering the access to the licensed bands in each location to local network administrators. These local administrators may then define rules which indicate which users can access which sub-bands at which times. However, as a multi-institute centre there often emerges the need to support cross-institute research that may result in spectrum access policy conflicts between the proponent of that research and the local administrators. In a relatively cohesive organisation such as CTVR such conflicts can be resolved by direct communication, however unresolved conflicts can be escalated to the CTVR Executive as the organisational arbiter of access control policies. The Executive may itself possess rules for resolving such conflicts, e.g. simple majority of executive committee members. The capture and execution of this policy resolution process is not easily supported in the DARPA XG policy language currently, largely due to limited mean for expressing policies about the authority to define policies and the organisational modelling this requires. In the next section we examine an generic mechanism based on the idea of hierarchical communities of policy makers that could address this deficiency in DARPA XG. Such flexibility in resolving conflicts in spectrum access policies from different bodies is essential if we wish to allow innovation in mediating access, for instance by using market-based rules to resolve conflicts.
Cognitive radio can imerging as the technology which alleviates the problem of spectrum scarcity.Orthogonal Frequency Division Multiplexing (OFDM) is a ideal transmission technique for Cognitive Radio (CR) networks because of its flexible nature to support Dynamic Spectrum Access(DSA).While this technique has two major drawbacks, Out Of Band (OOB) leakage due to high spectral sidelobe which cause interference with Primary Users (PU) operated in the adjacent band and high Peak to Average Power Ratio (PAPR). Many solutions were proposed for solving either of these problems individually or together.This paper presents survey of different precoding techniques for OOBR suppression and PAPR reduction.
Abstract: Cooperative Cognitive Radio Networks (CCRNs) incorporates cooperative communication into psychological feature radio networks, in which, primary users lease their spectrum to secondary users, and in exchange, the first users leverage secondary users as cooperative relays to boost their own turnout. Mobile operators offload their net traffic to in private in hand Wi-Fi access points (APs), a lot of to the inconvenience of non-cellular users served by the APs. However, by using the CCRN theme, the mobile operator will lease a commissioned channel to the AP, effectively doubling its capability. During this paper, propose Associate in nursing implementation of the CCRN framework applied to IEEE 802.11 WLANs. The cooperation is solid as a 2 player negotiation game wherever the 2 players’ ar the first users (users of the mobile operator) and also the secondary users (users of the AP before spectrum leasing) WHO cut price for either turnout share or channel time interval share. The best resource allocation that ensures potency likewise as fairness among users is provided by the Nash solution. Simulation results show that the users succeed higher turnout via the planned CCRN theme, so providing the mobile operator (e.g., AT&T) and also the personal Wi-Fi supplier (e.g., a Starbucks low shop) with incentives for cooperation.
We model the channel search and access policy for a CRN containing one SU by on open network. It will be extended to the multiuser case in the next sections. The networking is compressed of several nodes corresponding to different stages of spectrum sensing and packet transmission attempt of pack including channel sensing and packet transmission. In the proposed model, the arrival of a request to the queuing network presents the transmission attempt of a packet including channel sensing and handovers. The request leaves the network after in the service from a subset of nodes. Different handovers are modeled through nodes Hoi, i=1, 2… $, where $ is the maximum number of allowed handovers and will be discussed later. It is worth nothing that the first handover node does not really exist in the process of finding a transmission opportunity, and it appears just for providing symmetry in the model. Let Si denote the sensing process of i th channel. At the beginning of each time slot, an SU’s request enters the node HO1, and immediately is routed to the first sensing node, Si. After time units, the channel sensor routes the request to the transmitter nodes (node T*LPI or T*HP1) or to the second handover nod, HO2.
Cognitive Radio Ad Hoc Network (CRAHN) is a self-organized temporary network in which unlicensed users can access the spectrum of Primary Users in Primary Network during ideal time period of Primary Users. For this environment spectrum sensing sharing, management have important role to efficient use of spectrum. Due to this Quality of Service (QoS) analysis of spectrum is essential. In this paper we analyzed the performance of Spectrum in term of Throughput.
The direct sequence spreadspectrum based PSK spreading transceiver system is analyzed for their anti-jamming capability, low SNR. Except first simulation all subsequent simulation demonstrated to the performance of PSK spreading transceiver system. The first simulation demonstrated that the PSK spreading transmitted system is correctness. The power spectral density (PSD) for input and output signal show that the model that the theoretical model is conformed. Results show the help of Lab VIEW/ MATLAB with-spreading better performance.
Unauthorised copying is a major worry for many copyright holders. As digital equipment enables perfect copies to be created on amateur equipment, many are worried about lost revenues, and steps are introduced to reduce the problem. Technology to prevent copying has been along for a long time, but it is often controversial because it not only prevents unauthorised copying, but also a lot of the legal and fair use. A di ﬀ erent approach to the problem is to deter potential o ﬀ enders using technology to allow identification after the crime. Thus, the crime is not prevented, but the guilty users can be prosecuted. If penalties are su ﬃ ciently high, potential pirates are unlikely to accept the risk of being caught.
Figure shows that the blue line illustrates the method of LSB, whereas a red line depicting the spreadspectrum method. From Fig. 6 and 7 can be seen that the maximum number of characters that can be inserted using the LSB method and method of spreadspectrum in the same magnitude. It happened because in calculation formulas in use in finding the length of the message is the same, the difference method of the least significant bit with spreadspectrum method is in terms of the image will be inserted when processing the message. On the methods of LSB data to be inserted directly inserted into the picture without processed while the at a spreadspectrum method of data that will be on the insert must be in advance processed through XOR.