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Question: Discuss About The Frequency Spread Spectrum The Management? Answer: Introducation While wired communication may have the benefit of solid mediums to perform its operations, wireless communication uses a versatile and dynamic medium to transfer information. This medium is filled with many elements and conditions that change abruptly which necessitates the need to improve the performance of the signals being transmitted. FHSS will improve the quality of the signals by minimizing signal interference and fading through hopping technique that carries information from one signal band to another [1]. Now, to understand the operation of this technique its important to highlight the entire concept of spread spectrum. In general, there are two main types of spread spectrum; FHSS and DSSS (direct sequence spread spectrum). In both instances, the communication bandwidth i.e. the transmission signal is enlarged as compared to the bandwidth of the transmitted signal (original message). This variation accommodates the limitations of wireless communication particularly in the sho rt range application improving the quality of the signals [2]. FHSS as a component of spread spectrum will further its course by utilizing the frequencies of communication and randomly selected chipping codes. In essence, unique codes are used to generate spread chips that assign the transmitted signals carrier frequencies [1]. Through this operational procedure, the FHSS can be combined with modulation schemes to convert digital signals to analogue signals, an added advantage of the technique. However, while these operations take place, the communication process must ensure that the hops do not interfere with each other as they would cancel the entire process. Again, this process is accomplished using adaptive FH techniques that avoid signal collision and congestion during the hopping sequences. Literature review Many researchers and scholars who study spread spectrum techniques compare them to narrow band techniques, where the difference in the signal spectrum orientation is highlighted including the advantages of the methods. Now, while narrow band mobile communication may be efficient to use due to its operational structure that assigns users (subscribers) fractions of the communication channel, its allocation process is prone to many challenges. For one, the allocation process requires a well-coordinated process to assign the available frequencies to the different subscribers. Furthermore, having assigned the resources, the system must be aware of the drawbacks of jamming and interception of data more so, through eavesdropping techniques [3]. While there are many solutions to these problems, they can all be eliminated by the technique described above where the bandwidth is spread to fulfil the needs of the subscribers. FHSS like any other spread spectrum technique will increase the dimensional attributes of communication signals thus minimize the incidences of eavesdropping and any other form of interference. Furthermore, through the chipping codes that facilitate the hops of the carrier frequencies the transferred information is only distinguishable to the verified members. These operational conveniences have led to the application of the technique in modern wireless infrastructures such as WLAN (wireless local area networks) and Bluetooth communication. In all, when using FHSS, the following advantages are experienced: Minimal narrowband interferences. To understand the FHSS operation, we have to consider the Capacity formula as put forward by Shannon and Hartley [5]. In their theorem; C = B Log 2(1+S/N). Here, the C is the data in bits per seconds while the B highlights our required bandwidth. Therefore, for maximum information transmission, the value of B (BW) must be high to accommodate the data quota. Now, shifting back to FHSS, a carrier signal (encapsulates the message) moving from one frequency channel to another over a specific period of time. Moreover, the carrier frequency is accorded a wide range of frequencies (band) which maximizes the operational bandwidth hence improving the quality of the communication signals and also reduces the limitations (interferences and jamming) [5]. Now, during the hop activity, the data session or signal will remain in a given frequency channel for a specific period of time, which helps to maintain a consistent level of operation. According to the IEEE standards, this value should be 300 ms and is set as so in order to synchronize the operations of both the transmitter and receiver. In addition to this, the pattern of helthcare is dictated by a spreading code that is developed by a pseudo-random generating program. This program or generator is again synchronized between the transmitter and receiver in order to demodulate the signal at the reception stage. Therefore, when all is said and done, the transmitter and receiver must have a one to one synchronization for them to communicate [2]. A common feature or attribute that distinguishes FHSS from DSSS is the signal output given by the technique, instead of the envelope shaped signal (Sin X)/X)2 a flat output is given over the different frequencies used. Furthermore, size of the hopping bandwidth is usually N-times the total number of slots (frequency bands) available, where N is the bandwidth of each slot [6]. Identified by the IEEE 802.11 standard Operates within the 2.4 GHz band while having 79 frequencies (2.402 2.480GHz). Each of the frequencies outlined above is modulated (FSK) with a width of 1MHz[7]. FHSS Modulatio After highlighting the general operation method, its time to outline the modulation process used i.e. the transmission of the signal from a common FSHH transceiver. First, any signal interval can be chosen to highlight the process occupying one or even more frequency slots. Moreover, the frequency slot occupation is designated by the code generator which is usually a pseudo-noise (PN) sequence. Now, the most commonly used modulation method is usually M-ary FSK (frequency shift keying) and QAM (quadrature amplitude modulation). Therefore, the FSK is used to generate a signal at the start of transmission, with the output signalling the start of the modulation process. After, the FSK signal is converted into a frequency that is then synthesized with the frequency synthesizer. The resultant frequency is then combined with the overall output of the modulator forming a frequency-translated communication signal. This is the final product of the modulation process and is the signal transmitt ed over the channel [8]. NB: Note that, the PN generator produces N bits which are usually used to make the final 2N-1 frequency translations. Furthermore, the modulated signal is then transmitted using an AWGN (Additive white Gaussian noise) channel FHSS Demodulation (receiver section) In the receiver section of the transceiver, a similar PN generator is used to match the code used at the modulation stage. Furthermore, the generator at this end is synchronized with that of the input in order to match the operational frequency and slots used [9]. Moreover, its operation (PN generator) is also synchronized with the received signal so as to control the outcome of the resulting frequency synthesizer. Therefore, all the operations conducted at the transmitter are removed at this section, first, pseudorandom frequency conversion introduced is removed by mixing the product of the synthesizer with that of the received signal. Thereafter, the resulting product is demodulated using an M-FSK demodulator that matches the one at the transmitter [2]. NB: To maintain a synchronized operation, a signal or matching method is required between the PN generator and the frequency translated signal. This matching is usually done by the received signal as it dictates the terms of operation for it is the subject of the demodulation process. Furthermore, the improvements in FHSS operation and QAM as supported by Viterbi decoders which decrease the overall bit error rate [10]. FHSS Application As outlined before, FHSS offer improved signal performance as compared to narrow band technologies. This outcome makes its suitable for applications that use its corresponding operational frequency as highlighted in the figure above. Therefore, its mostly used for applications that require the operational frequencies of 2.4GHz and 3G. These applications are common among the military whose operations not only requires efficient systems bust also the utmost security. Now, both of these conditions are met by FHSS, where security is implemented using cryptographic structures and algorithms that generate unique chipping codes which are shared amongst the communicating parties. Moreover, FHSS is also used in wireless area networks (WLAN) where again it operates using the 97 frequency channels identified before. Now, in WLAN, it follows the operational band between 2.40 GHz and 2.480 GHz as highlighted in the figure above [11]. FHSS is also used in the modern digital systems, more so in the global positioning systems that outline objects positions. In all, the overall GPS system consists of several sections i.e. control unit, space unit and the user unit. Now, all these units exist independently and will use wireless communication to connect with each other which is where FHSS comes in hand offering its quality networking procedures. Moreover, FHSS is also used in other forms of wireless communication mostly because of its modulation process [12]. Finally, FHSS is also used in Bluetooth technologies. IV New Finding Optimized matched frequency hopping (OMFH) and optimized advanced frequency hopping (OAFH) are considered in this section. Now, traditional FHSS will just divide the overall communication band and spread the signal across them (hopping sequences). Moreover, the random pseudo code is used to deliver the allocation, however, this operational method is sometimes inefficient which has led to the new developments highlighted above. In essence, the overall performance of FHSS is improved by fading the frequency selection process and by use of adaptive frequency band jamming [13]. This outcome is accomplished by optimizing the control factors through matching hops and advanced frequency matching which improves the overall signal throughput. OMFH: In this technique, the regulation parameters of the FHSS are optimized and in this case, the only available factor is usually the sub-band frequencies for the hops. In essence, as one increases the number of sub-bands (hops) the signal interference decreases. In fact, an optimal operation is achieved when the sub-band frequencies are greater than 7 [14]. OAFH: Similarly, the regulation of FHSS parameters in done in this case, however, unlike the previous technique the respective sub-band frequencies are also regulated and optimized. Again, several sub-band are chosen but now each sub-band is regulated and optimized to increase the individual throughput which enhances the performance of FHSS beyond that of OFMH [15]. Conclusion From the analysis given in this report, FHSS has been outlined as a modulation technique that spread the communication spectrum based on the operational frequency. In all, in the technique, a number of sub-band frequencies are selected randomly using pseudorandom generators (PN) which designate the path for the transferred signals. After identifying the sub-frequencies, the signals are then hopped from one band to another which increases the operation bandwidth hence minimizing the limitation of wireless communication. Furthermore, the hops are strictly monitored based on a specific time interval, an outcome that makes the transiting signal immune to noises, distortions, jamming and interceptions. In addition to this, the presence of the chipping code generator (PN) makes the FHSS technique secure as it can be deployed using cryptographic parameters which can only be known by the communicating parties. Again, these operational conveniences make FHSS suitable for applications that req uire secure systems such as those of the military as identified above. References Badiger, M. Nagaraja and M. Kurian, "management Development of Frequency Hopping Spread Spectrum transmitter," IRD India, p. Available: https://www.irdindia.in/journal_ijeecs/pdf/vol2_iss4/5.pdf., Badiger, M. Nagaraja, M. Kurian and I. Rasheed, "Analysis, Design and Testing of Frequency Analysis, Hopping Spread Spectrum Transceiver Model Using MATLAB Simulink," International Journal of Advanced Research in Electrical Electronics and Instrumentation Engineering, pp. Available: https://www.rroij.com/open-access/analysis-design-and-testing-of-frequencyhopping-spread-spectrum-transceiver-modelusing-matlab--simulink.php?aid=42160, 2 Motlagh, "Frequency Hopping Spread Spectrum: An Effective Way to Improve Wireless Communication Performance," Department of Information Technology, Vaasa University of Applied Sciences, pp. Available: https://www.intechopen.com/books/advanced-trends-in-wireless-communications/frequency-hopping-spread-spectrum-an-effective-way-to-improve-wireless-communication-performance Vembu and S. Navaneethan, "Security Enhancement of Frequency Hopping Spread Spectrum Based On Oqpsk Technique," IOSR Journal of Electronics and Communication Engineering (IOSR-JECE), pp. Available: https://www.iosrjournals.org/iosr-jece/papers/Conf.15011/Volume%201/iosr%2010-62-70.pd David, K. Shama and K. Nayak, "Improved Performance Evaluation of Frequency Hopped Spread Spectrum using QAM/FSK Modulation Techniques," International Journal of Computer Applications (0975 8887), p. Available: https://eprints.manipal.edu/76369/1/ijca.pdf., 2012 Integrated, "An Introduction to Spread-Spectrum Communications," Tutorial 1890, pp. Available: https://www.maximintegrated.com/en/app-notes/index.mvp/id/1890, 2017 Schwartz, "Frequency Hopping Spread Spectrum (FHSS) vs. DSSS vs. BWA and WLAN," FHSS vs. DSSS, pp. Available: https://sorin-schwartz.com/white_papers/fhvsds.pdf., 2016 Torvmark, "Frequency Hopping Systems," Application NoteAN014, p. accounting: https://www.ti.com/lit/pdf/swra077., 2 Seth and V. 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Available: https://www.ijsps.com/uploadfile/2015/0915/20150915101611816.pdf., 201 Mathur, "Wireless Technology Is Ready For Industrial Use," pp. Available: https://www.miinet.coFHSS Modulatioroved Jamming-Resistant business Hopping Spread Spectrum Systems," A thesis, pp. Available: https://curve.carleton.ca/system/files/etd/3ca5b480-565a-4721-8199-2339ad2af5df/etd_pdf/a661b46493258918a040b402f54e24e5/atta-improvedjammingresistantfrequencyhoppingspread.pdf., 2014 Burke, C. Hume and J. Meza, "Spread Spectrum jamming," CALIFORNIA POLYTECHNIC STATE UNIVERSITY, p. Available: https://www.google.com/url?sa=trct=jq=esrc=ssource=webcd=4cad=rjauact=8ved=0ahUKEwi74LaJ457WAhWIDsAKHSeFBZYQFgg1MAMurl=http%3A%2F%2Fdigitalcommons.calpoly.edu%2Fcgi%2Fviewcontent.cgi%3Farticle%3D1234%26context%3Deespusg=AFQjCNE_apTBCP, 2013. Atta, "ADVANCED FREQUENCY HOPPING SPREAD SPECTRUM TECHNIQUES FOR INTERFERENCE LIMITED FADING WIRELESS CHANNELS," Research gate, p. 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