A Delay-Aware Caching Algorithm for Wireless D2D Caching Networks

Recently, wireless caching techniques have been studied to satisfy lower delay requirements and offload traffic from peak periods. By storing parts of the popular files at the mobile users, users can locate some of their requested files in their own caches or the caches at their neighbors. In the latter case, when a user receives files from its neighbors, device-to-device (D2D) communication is enabled. D2D communication underlaid with cellular networks is also a new paradigm for the upcoming 5G wireless systems. By allowing a pair of adjacent D2D users to communicate directly, D2D communication can achieve higher throughput, better energy efficiency and lower traffic delay. In this work, we propose a very efficient caching algorithm for D2D-enabled cellular networks to minimize the average transmission delay. Instead of searching over all possible solutions, our algorithm finds out the best pairs, which provide the best delay improvement in each loop to form a caching policy with very low transmission delay and high throughput. This algorithm is also extended to address a more general scenario, in which the distributions of fading coefficients and values of system parameters potentially change over time. Via numerical results, the superiority of the proposed algorithm is verified by comparing it with a naive algorithm, in which all users simply cache their favorite files

SIMULASI RAILWAYS BACKBONE COMMUNICATION SYSTEM (RBCS) MENGGUNAKAN DEDICATED SHORT RANGE COMMUNICATION (DSRC) PADA JARINGAN NIRKABEL 802.11P

ABSTRAKSI: Telah banyak penggunaan media wireless dalam kehidupan sekarang ini, antara lain Wireless Fire Alarm System dan Implementasi Wireless for Traffic Avoidance. Wireless Fire Alarm System masih menggunakan jaringan nirkabel 802.11a/b/g karena media yang digunakan bersifat statis atau hanya diam pada satu tempat saja, sedangkan Implementasi Wireless for Traffic Avoidance sudah menggunakan jaringan nirkabel 802.11p pada peralatan transportasi yang cenderung dinamis atau selalu bergerak. Dalam tugas akhir ini, dibangun simulasi Railways Backbone Communication System (RBCS) menggunakan NS-2 simulator untuk mengimplementasikan penggunaan Dedicated Short Range Communication (DSRC) pada jaringan nirkabel 802.11p. Performansi sebuah jaringan nirkabel 802.11p sangat berpengaruh pada connectivity pada masing – masing peralatan. Sedangkan connectivity sendiri dipengaruhi oleh packet loss, throughput dan delay. Simulasi dibangun dengan menggunakan ns-2 sebagai simulator untuk mensimulasikan kerangka RBCS dengan menempatkan beberapa device wireless statis (protokol 802.11p). Kemudian digunakan node dinamis sebagai implementasi kereta api. Pengaruh kecepatan pada kereta api pasti berpengaruh saat kereta api bertemu dengan salah satu device, yang statis maupun yang bergerak yaitu kereta api itu sendiri dari arah lain. Simulator ini ( ns-2 ) versi 2.3.4 yang dipakai oleh penulis sendiri sudah mendukung protokol 802.11p. Dari analisis parameter – parameter masukan yang sudah dihitung dan diamati dari gambar serta grafik yang dibuat, penulis menyimpulkan bahwa kecepatan mempunyai pengaruh yang cukup signifikan terhadap konektivitas device 802.11p dengan melihat parameter – parameter yang sudah dihitung. Semakin tinggi kecepatan sebuah wireless mobile node, semakin sedikit paket yang dapat dikirim olehnya. Selain itu, penambahan kecepatan membuat paket yang diterima oleh base station juga semakin sedikit. Konektivitas antara wireless mobile node dengan wired node masih dapat terjaga selama kecepatan wireless mobile node tidak terlalu tinggi. Konektivitas antara sesama wireless mobile node juga masih dapat terjaga selama kecepatan node pertama tidak berselisih terlalu jauh dengan kecepatan node yang kedua.Kata Kunci : Railways Backbone Communication System (RBCS) , Dedicated Short Range Communication (DSRC) , connectivity, packet loss, throughput, delay, 802.11a/b/g, 802.11p, ns-2ABSTRACT: It has been a lot of use of wireless media in this present life, such as Wireless Fire Alarm System and Implementation of Wireless for Traffic Avoidance. Wireless Fire Alarm System still use the 802.11 a/b/g wireless Networks because of the media used to be static or just rest at one place only, while the Implementation of Wireless for Traffic Avoidance already using the wireless Network 802.11p on transportation equipment that tend to dynamic or constantly on the move. In this thesis, simulations built Railways Backbone Communication System (RBCS) using the NS-2 simulator to implement the use of Dedicated Short Range Communication (DSRC) at 802.11p wireless Network. The performance of a wireless Network 802.11p badly affected by the connectivity on each equipment. Meanwhile connectivity itself is influenced by packet loss, throughput and delay. Simulation was built using the ns-2 as a simulator to simulate framework of RBCSs by putting some static wireless device (802.11p) protocol. Dynamic node is then used as the implementation of the train. Effect of speed on the train when the train certainly influential meeting with one device, the static and the moving of the train itself from the other direction. The simulator (ns-2) version 2.3.4 used by the authors themselves already support 802.11p protocol. From the analysis of the input parameters are already calculated and observed from the images and graphs are made, the authors conclude that the speed has significant influence on the connectivity of 802.11p device by looking at the parameters that have been counted. The higher speed of mobile wireless nodes, the fewer packet can be sent by it. Moreover, the addition of speed makes the packet received by the Base Station is also less. The connectivity between wireless mobile nodes with wired nodes can still be awake for speed of mobile wireless node is not to high. Connectivity among wireless mobile nodes also may be awake during the first node does not quarrel to much with the speed of second node.Keyword: Railways Backbone Communication System (RBCS) , Dedicated Short Range Communication (DSRC), connectivity, packet loss, throughput, delay, 802.11a/b/g, 802.11p, ns-