Browsing by Author "Yinusa Ademola Adediran"

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Cognitive Radio Networks, a Key Technology of Future Wireless Communication: Challenges and Opportunities
(IUP Journal of Telecommunications, 2012-11-01) Ajiboye, Johnson Adegbenga; Yinusa Ademola Adediran
It is a well-known and established fact that the current approach of fixed spectrum allocation, the command-and-control model, makes the spectrum or the finite resource to be grossly underutilized or inefficient. There are so many bands of the spectrum already licensed to users but which in reality are unoccupied at some instance in time thereby creating spectrum holes. These are 'opportunities' that could be harnessed. Cognitive Radio (CR) is a promising technology being envisioned to solve the problem of spectrum underutilization and allows for real-time spectrum management. The CR, in a non-interference basis, opportunistically explores the unused channel, thereby ensuring efficient usage of this 'scarce' resource. The CR is a sure technology for the next generation wireless systems. In a CR, a licensed user, also called a Primary User (PU), has a priority over the Secondary User (SU) which has no spectrum license. Therefore, at the arrival of a PU, an opportunistic SU vacates the occupied channel and seeks another empty channel to be allocated. In this way, spectral efficiency is greatly enhanced. In this work, we examine the challenges that this new technology is bound to face.
Dynamic Spectrum Access (DSA) in Wireless Cognitive Radio Networks (WCRN)
(2013-02-01) Ajiboye, Johnson Adegbenga; Yinusa Ademola Adediran; Mary Adebola Ajiboye
Dynamic Spectrum Access (DSA) is a technology that senses the unused 'free' but allocated portion of the radio frequency spectrum on a non-interfering basis. These unused bands are also known as 'holes' or 'white spaces'. DSA also refers to the time-varying, flexible usage of parts of the radio spectrum under consideration of regulatory and technical restrictions. This type of spectrum access is due to the dynamic behavior that the Secondary User (SU) must employ in order to access the spectrum, while avoiding interfering with a Primary User (PU). Intelligent or Cognitive Radio (CR) is a platform on which the DSA can be implemented. CRs are radio systems that autonomously coordinate the usage of spectrum. They utilize radio spectrum when it is not being used by incumbent (primary) radio systems. Underutilized spectrum can be exploited with the concepts of DSA and CR. This paper reviews the techniques that can be deployed for DSA reliably in a Wireless Cognitive Radio Network (WCRN) and models of network architecture-based DSA in Cognitive Radio Networks (CRN).
Performance Analysis of Statistical Time Division Multiplexing Systems
(Leonardo Electronic Journal of Practices and Technologies, 2010) Ajiboye, Johnson Adegbenga; Yinusa Ademola Adediran
Multiplexing is a way of accommodating many input sources of a low capacity over a high capacity outgoing channel. Statistical Time Division Multiplexing (STDM) is a technique that allows the number of users to be multiplexed over the channel more than the channel can afford. The STDM normally exploits unused time slots by the non-active users and allocates those slots for the active users. Therefore STDM is appropriate for bursty sources. In this way STDM normally utilizes channel bandwidth better than traditional Time Division Multiplexing (TDM). In this work, the statistical multiplexer is viewed as M/M/1queuing system and the performance is measured by comparing analytical results to simulation results using Matlab. The index used to determine the performance of the statistical multiplexer is the number of packets both in the system and the queue. Comparison of analytical results was also done between M/M/1 and M/M/2 and also between M/M/1 and M/D/1 queue systems. At high utilizations, M/M/2 performs better than M/M/1. M/D/1 also outperforms M/M1.
Performance Analysis of Statistical Time Division Multiplexing Systems
(Leonardo Electronic Journal of Practices and Technologies, 2010-01) Ajiboye, Johnson Adegbenga; Yinusa Ademola Adediran
Multiplexing is a way of accommodating many input sources of a low capacity over a high capacity outgoing channel. Statistical Time Division Multiplexing (STDM) is a technique that allows the number of users to be multiplexed over the channel more than the channel can afford. The STDM normally exploits unused time slots by the non-active users and allocates those slots for the active users. Therefore STDM is appropriate for bursty sources. In this way STDM normally utilizes channel bandwidth better than traditional Time Division Multiplexing (TDM). In this work, the statistical multiplexer is viewed as M/M/1queuing system and the performance is measured by comparing analytical results to simulation results using Matlab. The index used to determine the performance of the statistical multiplexer is the number of packets both in the system and the queue. Comparison of analytical results was also done between M/M/1 and M/M/2 and also between M/M/1 and M/D/1 queue systems. At high utilizations, M/M/2 performs better than M/M/1. M/D/1 also outperforms M/M1.
Queue Behavior of Statistical Multiplexers
(The IUP Journal of Information Technology, 2013-03-01) Ajiboye, Johnson Adegbenga; Yinusa Ademola Adediran; Mary Adebola Ajiboye
In a statistical multiplexer, packets are assumed to be arriving at the multiplexer with the inter arrival times being Independent and Identically Distributed (IID). The service time is also IID. The inter arrival times are generated from the corresponding probability distribution. When a packet arrives to an empty or idle system, the packet is immediately served; otherwise, it is queued. In this paper, the queue behaviors in the multiplexer's buffer were examined. The results show that the average number of packets in the multiplexer queue increases in an exponential form with increase in utilization; and at high utilization, there is a dramatic increase in the number of packets in the multiplexer queue which may lead to packet loss when there is no sufficient buffering. Comparison of the simulation and analytical results for the mean number of packets in an M/M/I Multiplexer Queue reveals that results are within ±23% for offered load of up to 90%.