Cryptocurrencies acquire user confidence by making the whole creation and transaction history transparent to the public. In exchange, the transaction history accurately captures the complete range of user activities related to cryptocurrencies. It is thought to be one of the safest and simplest payment methods that may be employed in the future. The trend of banks and other financial institutions investing in cryptocurrencies has increased rapidly in recent years. Therefore, it is necessary to synthesize the findings of previous studies on cryptocurrencies. In this paper, the use of data mining methods in Bitcoin transactions is analyzed and summarized. Cryptocurrencies, similar to the well-known Bitcoin, were targeted to ensure transaction security and privacy and overcome the drawbacks of traditional banking systems as well as other centralized systems. In addition, a comprehensive analysis of the literature on the challenges and applications of electronic currencies is conducted. The evolution of digital currency from electronic cash to cryptocurrencies is summarized and the methods used to increase user privacy are highlighted. The security threats in existing cryptocurrency systems (that compromise the privacy of Bitcoin users) are also highlighted. Finally, several research gaps and trends are identified that need to be further explored.

The IEEE 802.11p standard drafted to support wireless access in vehicular environments (WAVE) or vehicular ad hoc network (VANET) which uses Enhanced Distributed Channel Access (EDCA) mechanism for the contention-based prioritized Quality of Service (QoS) at the MAC layer. The EDCA mechanism defines four access categories (ACs). Each AC queue works as an independent DCF station (STA) with Enhanced Distributed Channel Access Function (EDCAF) to contend for Transmission Opportunities (TXOP) using its own EDCA parameters. This paper provides an analytical model to compute the performance of the IEEE 802.11p Enhanced Distributed Channel Access Function (EDCAF) for Vehicular Network. To develop the model the four access categories (ACs) and all the major factors that could affect the performance are considered. The relationship among the IEEE 802.11p EDCA parameters and performance matrices are derived through Markov chain based theoretical analysis. Moreover, the derived performance model is verified by simulation.

Daha yüksek hizmet kalitesi, veri hızları, kapasite ve azalan gecikmeye yönelik artan ihtiyaç nedeniyle, hücresel iletişim gün geçtikçe gelişmektedir. Hücresel ağların tasarımı, bu talepleri karşılamak için önemli ölçüde geliştirilmektedir. Yeni çoklu erişim yöntemleri, modülasyon teknikleri, gelişen teknolojiler vb. sayesinde ihtiyaç ve talepler karşılanmaktadır. Bu çalışmada, birinci nesilden (1G) altıncı nesle (6G) kadar hücresel evrim üzerine kapsamlı bir çalışma sunulmaktadır. Çalışmada hücresel ağ tasarımları, çoklu erişim stratejileri, modülasyon teknikleri ve gelişen teknolojiler ele alınmıştır. Hücresel ağın mimarisi 1G'den 5G'ye kadar verilmiştir. Mimariyi geliştirmek ve kullanıcı taleplerini karşılamak için ortaya çıkan en önemli teknolojilerden bazıları ele alınmaktadır. Massive MIMO, yazılım tanımlı ağ, mmWave ve diğer gelecek teknolojiler bun önemli teknolojiler arasındadır. Ek olarak, 1G'den 5G'ye kadar çeşitli erişim mekanizmaları araştırılmaktadır. Birkaç nesil hücresel iletişimin bir karşılaştırması bulunmaktadır. Çalışma ayrıca yaklaşan 6G'nin neler getirebileceğine dair bir ön izleme sunmaktadır. 6G ile ilgili tartışılan zorluklar ve sorunlar açıklanmaktadır.

Wireless communication technologies are becoming increasingly important in today's rapidly developing technological world. The widespread use of the Internet, the popularity of smartphones and other mobile devices, and the rise in industrial applications have all contributed to the start of a new wireless communication technology revolution. As a result, 6th generation (6G) wireless communication technology is intended to provide enhanced performance features such as faster speeds, larger bandwidths, lower latency, higher connection density, and improved reliability. mmWave-band communications are already having a vital impact on 5G. Similarly, communications in the TeraHertz (THz)-band will be crucial for the next 6G and beyond. THz, mmWave, and RF communication technologies constitute the fundamental pillars of 6G; therefore, a comparative analysis of these technologies is essential for the robust design and development of future 6G networks. In this paper, a study of THz, mmWave, and RF communication technologies is presented with their roles in developing the 6G network. Firstly, an overview of THz, mmWave and RF technologies is presented. Then, the conventional channel modeling is discussed. After that, artificial intelligence (AI) based channel modeling is presented. Furthermore, challenges and future research directions are highlighted based on the current state of the art.

Cryptocurrencies acquire user confidence by making the whole creation and transaction history transparent to the public. In exchange, the transaction history accurately captures the complete range of user activities related to cryptocurrencies. In this paper, the use of data mining methods in Bitcoin transactions is analyzed and summarized. Cryptocurrencies, similar to the well-known Bitcoin, were targeted to ensure transaction security and privacy and overcome the drawbacks of traditional banking systems as well as other centralized systems. We also conduct a thorough analysis of the literature on the challenges and applications of electronic currencies. We outline the evolution of digital currency from electronic cash to cryptocurrencies and put the spotlight on the methods used to increase user privacy. We also highlight security threats in the existing cryptocurrency systems that jeopardize the privacy of Bitcoin users. Finally, we identify several research gaps and trends that need to be looked at further.