Single carrier frequency division multiple access (SC-FDMA) has been comprehensively investigated and standardized in 4th generation (4G) and 5th generation (5G) mobile systems. Its significant advantage is low peak-to-average power ratio (PAPR), which makes it suitable for uplink channel communications. However, over a long time period, SC-FDMA has not made breakthrough especially in data rate enhancement, which may not catch up with the next generation evolution in communications. This work proposes to use a non-orthogonal waveform in SC-FDMA to promote a new concept, termed single carrier spectrally efficient frequency division multiple access (SC-SEFDMA). This non-orthogonal single carrier access technique maintains essentially similar complexity as SC-FDMA but advantageously can either achieve higher data rate for the same amount of power consumption or the same data rate with less power consumption.
This paper serves as an evaluation of an experimental wireless communications technique called space-time coded massive (STCM) multiple-input multiple-output (MIMO). The STCM-MIMO system utilizes two massive MIMO antenna arrays which transmit data over two channel vectors to a user with one receive antenna. This configuration permits the system to use the asymptotic orthogonal qualities of massive MIMO pre-coding to eliminate the interference from other users’ channel vectors and signals. The system also maintains the diversity of space-time codes to recover lost data through treating each transmitting massive MIMO array similarly to how a 2×1 Alamouti spacetime code would treat each transmitting antenna. Our results show that a wireless system with the proposed STCM-MIMO technology can significantly outperform those with space-time coding techniques.
This paper presents a mesh architecture proposal called Mobile mEsh Network to Aid in CountEring drug TRAffiCKing (M.E.N.A.C.E-TRACK). This project was born from the hypothesis we could establish a covert network channel independent of the cell phone companies infrastructures. Therefore, law enforcement agencies could establish connection with field personnel, in a fault tolerant fashion allowing the transmission of multimedia data (instead of only voice). The main contribution for this paper is the strategies involved to configure smartphones on the MANET side of this system. We present the main difficulties and one possible solution to implement ad hoc mode on our testbed so we can enable a MANET organization on M.E.N.A.C.E-TRACK.
This paper tackles the challenging task of developing accurate easy-to-use analytical models for performance evaluation of WiMAX networks. The need for precise fast-computing tools is of primary importance to face complex dimensioning issues of WiMAX cells. Here, we present generic Markovian models developed for the rtPS service class defined in the WiMAX standard. This service class is dedicated to real-time applications with constraints on both their bit rates and the latency of their packets (i.e., streaming). Our analytical modeling is performed in two steps. First, we focus on the connection level only considering the bit rate constraint. Then, we extend the model to the packet level to formulate the packet delay QoS parameter. The resulting models can account for multiple traffic profiles at both levels while always keeping an instantaneous resolution. The models are compared with simulations that show their accuracy. Finally, we show how our models can be used to solve dimensioning issues while avoiding days of simulations.
