AODV-UI Proof of Concept on MIPS-based Wireless Router

AODV routing protocol facilitates changing and simple-to-setup network environment. It helps setting up a network without sufficient infrastructure, such as in disaster area. Development of AODV protocol has gathered a worldwide research interest. However, not many researches implement AODV routing protocol in real mobile nodes and real MANET. In addition, real implementation deals with other works concerning underlying protocol, firmware and hardware configuration, as well as detailed topology both in logical and physical arrangement. This work aims to implements Ad-hoc On-demand Distant Vector – particularly University of Indonesia AODV (AODV-UI) routing protocol on low-end inexpensive generic wireless routers as a proof of concept. AODV-UI is an improved version of AODV routing protocol that implements gateway interconnection and reverse route capability. This routing protocol has been previously successfully tested in NS-2. In this work, current AODV-UI protocol is ported to OpenWRT + MIPS (Microprocessor without Interlocked Pipeline Stages) little endian architecture then tested on the real networking environment. Underlying media access layer is also altered to provide the protocol greater control over the network. Performance of this implementation is measured in terms of energy consumption, routing overhead, end-to-end delay, protocol reliability and packet delivery ratio

Two-phase random access procedure for LTE-A Networks

Simultaneous random access attempts from massive machine-type communications (mMTC) devices may severely congest a shared physical random access channel (PRACH) in mobile networks. This paper presents a novel two-phase random access (TPRA) procedure to deal with the congestion caused by mMTC devices accessing the PRACH. During the first phase, the TPRA splits the mMTC devices into smaller groups according to a preamble selected randomly by the devices. Then, in the second phase, each group of devices is assigned with a dedicated channel to complete the random access procedure. The proposed concept allows a base station to adjust the number of dedicated channels in real-time according to the actual network load. We then present an analytical model to estimate the access success probability and the average access delay of the TPRA. Finally, we propose a simple formula to determine the optimal number of random access resources for the second phase of the proposed TPRA. Simulations are carried out to validate the analytical models and to demonstrate the benefits of the TPRA compared to competitive techniques

Repetitions versus retransmissions: Tradeoff in configuring NB-IoT random access channels

Narrowband Internet of Things (NB-IoT) is a cellular standard supporting IoT applications in wide area. NB-IoT utilizes "repetition" to extend the coverage of the base station. The repetition value in NB-IoT physical random access channel (NPRACH) is set to ensure 99% detection probability without considering the inherent "retransmission" nature of NPRACH. In this paper, we try to optimally trade extra time-diversity gain in preamble transmission obtained from retransmission to reduce the repetition requirement in NB-IoT. The preferred regions for pure repetition and retransmission schemes sharing the same amount of NPRACH resource under various offered loads and channel conditions are first investigated. The optimal amount of NPRACH resource, repetition value, and retransmission value are then obtained subject to a target successful probability. The results show that the embedded retransmission nature of NPRACH can effectively reduce the number of repetitions. High number of repetitions is required only under worse channel condition