Due to relative mobility, topology changes rapidly with frequent link breakage in vehicular ad hoc networks (VANETs). Clustering VANETs into small groups limits channel contention and controls the network topology efficiently. In this study, a novel cluster‐based medium access control (CB‐MAC) protocol is proposed for VANETs. The cluster formation process is defined. Moreover, cluster head election and cluster merging processes are described for efficient communication in the cluster as well as out of the cluster. The mechanism defined in IEEE 802.11 standard is specially designed for only direct communications and is not suitable for cluster‐based communications. Therefore, new control packets are introduced and the existing control packet format is modified to support cluster‐based communications. For effective MAC protocol design, the request to send (RTS)/clear to send (CTS) mechanism is not used for safety messages which are of broadcast nature. On the other hand, the RTS/CTS mechanism is used for non‐safety data delivery to eliminate hidden node problem. Markov chain model‐based analytical model is presented to explore the performance of the proposed CB‐MAC protocol. The proposed protocol is validated by numerical studies. The numerical results exhibit that the proposed CB‐MAC protocol improves system performance and satisfies the delay constraint of 100 ms for safety messages.

In vehicular ad hoc networks (VANETs), mobility among vehicles can result in rapid topology changes with frequent link breakage and unstable communications, which cause collision and packet loss. Conversely, cooperative transmission can improve communication reliability and can enhance communication rate with lower delay by alleviating wireless channel impairments caused by mobility in VANETs. In this study, a novel reliable and efficient cooperative medium access control protocol for VANETs (RECV‐MAC) is proposed. Since a random access mechanism is suitable and efficient because of the dynamic and open nature of VANETs, authors used the random access approach, i.e. carrier sense multiple access with collision avoidance, which is used by IEEE 802.11p. The RECV‐MAC protocol is compatible with IEEE 802.11p. New control messages are introduced to support cooperative communication. The mechanism is defined to choose suitable transmission mode as well as to select optimal helper. To investigate the performance of RECV‐MAC protocol, Markov chain model‐based analytical analysis is provided. The RECV‐MAC protocol is validated by numerical results which demonstrate that RECV‐MAC protocol improves the performance with higher throughput, enhances the reliability of communication by decreasing packet dropping rate (PDR), and decreases delay, in particular, satisfies the delay constraint of 100 ms for sm.

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.

Fifth-generation advanced (5G-A) and sixth-generation (6G) networks in ultra-dense and smart cities offer an efficient solution for addressing the growing number of mobile users while ensuring high throughput and full coverage. However, the handover decision (HOD) remains a critical challenge in wireless networks, especially for high-speed users in millimeter-wave (mmWave) communication environments. The present paper proposes a mobility-awareness HOD algorithm that combines two decision algorithms: reference signal received power (RSRP) and signal-to-interference-plus-noise ratio (SINR). The algorithm makes decisions based on real-time user experiences collected every 40 milliseconds during the user’s mobility. The research was conducted using MATLAB 2023a and advanced 5G and 6G tools. All system settings, functions, mobility models, and simulation criteria were defined based on 3GPP specifications. The algorithm guarantees high-quality connectivity and smooth user transitions across 5G and 6G networks under diverse mobility conditions. The results show that Systems 2 and 4 minimize 96.97% and 99.99% of handover ping-pong (HOPP) compared with Systems 1 and 3. The simulation results reveal that the proposed algorithms in Systems 2 and 4 provide noticeable enhancements in network performance, with radio quality metrics of 16.32% and 8.04% for RSRP, 168.99% and 407.31% for SINR levels, and 55.11% and 16.04% improvements in throughput across various mobile speed scenarios compared with Systems 1 and 3.