Medium access control protocol design for wireless communications and networks review

Medium access control (MAC) protocol design plays a crucial role to increase the performance of wireless communications and networks. The channel access mechanism is provided by MAC layer to share the medium by multiple stations. Different types of wireless networks have different design requirements such as throughput, delay, power consumption, fairness, reliability, and network density, therefore, MAC protocol for these networks must satisfy their requirements. In this work, we proposed two multiplexing methods for modern wireless networks: Massive multiple-input-multiple-output (MIMO) and power domain non-orthogonal multiple access (PD-NOMA). The first research method namely Massive MIMO uses a massive number of antenna elements to improve both spectral efficiency and energy efficiency. On the other hand, the second research method (PD-NOMA) allows multiple non-orthogonal signals to share the same orthogonal resources by allocating different power level for each station. PD-NOMA has a better spectral efficiency over the orthogonal multiple access methods. A review of previous works regarding the MAC design for different wireless networks is classified based on different categories. The main contribution of this research work is to show the importance of the MAC design with added optimal functionalities to improve the spectral and energy efficiencies of the wireless networks

Survey of Spectrum Sharing for Inter-Technology Coexistence

Increasing capacity demands in emerging wireless technologies are expected to be met by network densification and spectrum bands open to multiple technologies. These will, in turn, increase the level of interference and also result in more complex inter-technology interactions, which will need to be managed through spectrum sharing mechanisms. Consequently, novel spectrum sharing mechanisms should be designed to allow spectrum access for multiple technologies, while efficiently utilizing the spectrum resources overall. Importantly, it is not trivial to design such efficient mechanisms, not only due to technical aspects, but also due to regulatory and business model constraints. In this survey we address spectrum sharing mechanisms for wireless inter-technology coexistence by means of a technology circle that incorporates in a unified, system-level view the technical and non-technical aspects. We thus systematically explore the spectrum sharing design space consisting of parameters at different layers. Using this framework, we present a literature review on inter-technology coexistence with a focus on wireless technologies with equal spectrum access rights, i.e. (i) primary/primary, (ii) secondary/secondary, and (iii) technologies operating in a spectrum commons. Moreover, we reflect on our literature review to identify possible spectrum sharing design solutions and performance evaluation approaches useful for future coexistence cases. Finally, we discuss spectrum sharing design challenges and suggest future research directions

Analysis of asymmetry of traffic in full-duplex wireless local area network

Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáThe standard commodity wireless hardware is half-duplex because there are challenges in full-duplex wireless that need attention and improvement. The self-interference in radios is one of the big challenges, but, even though there is no standard yet, there are several proposals that cancel enough self-interference that it is possible for communication to be successfully made. The standard half-duplex rules of the media access control (MAC) protocol contained on wireless cards do not accept simultaneous transmissions, because simultaneous transmissions are likely to collide with each other. Therefore, full-duplex wireless networks need a new MAC protocol to be able to handle the different full-duplex transmissions, namely, symmetric and asymmetric. Symmetric full-duplex transmissions ocurr between just two stations, which can be managed trivially by a suitable MAC protocol. On the other hand, asymmetric transmissions occur in communications involving three stations, and those transmissions are likely to produce collisions if one station receives simultaneously signals from the two others. From the different difficulties of each transmission type, emerges the doubt about how many opportunities are there for a full-duplex wireless network to make each type of transmission. With the focus on this question, this research proposes a method to collect traffic data from a real half-duplex wireless local area network (WLAN) to measure the amount of full-duplex symmetric and asymmetric transmission opportunities. The proposed method relies on: the brcmfmac driver, to collect the traffic data in kernel space; the Ftrace tracing utility framework, to send the data from kernel to user space; a Raspberry Pi 3 B+, in which is installed the modified driver and tracing utility; and an estimate of the travel time of frames between the kernel and firmware. The results of this research include a method to collect traffic data with the goal of measuring the amount of full-duplex transmissions opportunities and their types in a real half-duplex WLAN. It is also presented the analysis of a small amount of data collected during four days as an example of the proposed method, which shows that 4.096% of the frames presented the proper conditions to symmetric transmissions, while only 0.025% in the case of asymmetric transmissions.Os dispositivos sem fio padrão são half-duplex, pois o full-duplex sem fio apresenta desafios que precisam receber atenção e melhorias. A auto-interferência presente é um dos desafios, mas, ainda que não haja padrão, existem algumas propostas que cancelam a auto-interferência a ponto de comunicações serem realizadas com sucesso. As regras padrão do protocolo de controle de acesso ao meio (MAC) half-duplex contido nas placas sem fio não permitem transmissões simultâneas, já que são propensas a causar colisões. Portanto, redes full-duplex sem fio precisam de um novo protocolo MAC para que os diferentes tipos de transmissão full-duplex (simétrico e assimétrico) sejam utilizados. As transmissões simétricas ocorrem em comunicações entre apenas duas estações, o que pode ser gerido de forma trivial por um protocolo MAC apropriado. Por outro lado, as transmissões assimétricas envolvem comunicações entre três estações, e estas transmissões são propensas a gerar colisões no caso de uma das estações receber sinal das outras duas, simultaneamente. Devido às diferentes dificuldades de cada tipo de transmissão, surge a dúvida sobre quantas oportunidades existem para comunicação full-duplex de cada tipo de transmissão. Com foco nessa questão, esta pesquisa propõe um método para coleta de dados de tráfego de uma rede de área local sem fio (WLAN) half-duplex com o objetivo de calcular a quantidade de oportunidades de transmissões full-duplex simétricas e assimétricas. O método proposto conta com: o driver brcmfmac, para coleta de dados de tráfego em ambiente de kernel; o Ftrace, ferramenta utilitária de rastreamento, usado para enviar os dados do kernel para o ambiente do usuário; um Raspberry Pi 3 B+, no qual é instalado o driver modificado e o utilitário de rastreamento; e, um cálculo para estimar o tempo de viagem de pacotes entre o kernel e o firmware. Os resultados desta pesquisa incluem um método de coleta de dados de tráfego com o objetivo de quantificar as oportunidades de transmissões full-duplex e seus tipos em uma WLAN real. Também é apresentado uma coleta feita por quatro dias como um exemplo do mesmo. A análise mostra que 4.096% dos pacotes apresentam condições adequadas para transmissões simétricas, e apenas 0.025% para transmissões assimétricas

Simultaneous Transmission and Reception: Algorithm, Design and System Level Performance

Full Duplex or Simultaneous transmission and reception (STR) in the same frequency at the same time can potentially double the physical layer capacity. However, high power transmit signal will appear at receive chain as echoes with powers much higher than the desired received signal. Therefore, in order to achieve the potential gain, it is imperative to cancel these echoes. As these high power echoes can saturate low noise amplifier (LNA) and also digital domain echo cancellation requires unrealistically high resolution analog-to-digital converter (ADC), the echoes should be cancelled or suppressed sufficiently before LNA. In this paper we present a closed-loop echo cancellation technique which can be implemented purely in analogue domain. The advantages of our method are multiple-fold: it is robust to phase noise, does not require additional set of antennas, can be applied to wideband signals and the performance is irrelevant to radio frequency (RF) impairments in transmit chain. Next, we study a few protocols for STR systems in carrier sense multiple access (CSMA) network and investigate MAC level throughput with realistic assumptions in both single cell and multiple cells. We show that STR can reduce hidden node problem in CSMA network and produce gains of up to 279% in maximum throughput in such networks. Finally, we investigate the application of STR in cellular systems and study two new unique interferences introduced to the system due to STR, namely BS-BS interference and UE-UE interference. We show that these two new interferences will hugely degrade system performance if not treated appropriately. We propose novel methods to reduce both interferences and investigate the performances in system level.Comment: 20 pages. This manuscript will appear in the IEEE Transactions on Wireless Communication

Interval-based maximum likelihood benchmark for adaptive second-order asynchronous CCI cancellation

© Copyright 2007 IEEEA potential usefulness of a priori time-of-arrival (TOA) information for asynchronous co-channel interference (CCI) cancellation is addressed. An interval-based maximum likelihood (ML) benchmark is developed and compared to the averaged ML benchmark and regularized second-order semi-blind (SB) solution that do not use the TOA information. It is found that in short burst scenarios the SB algorithm demonstrates performance that is close to the interval-based ML benchmark. Furthermore, it is shown that SB may outperform the ML benchmarks in the ML breakdown situation. For longer bursts, the known TOA information can significantly improve the performance.Kuzminskiy, A.M. and Abramovich, Y.I

Link Scheduling Algorithms For In-Band Full-Duplex Wireless Networks

In the last two decades, wireless networks and their corresponding data traffic have grown significantly. This is because wireless networks have become an indispens- able and critical communication infrastructure in a modern society. An on-going challenge in communication systems is meeting the continuous increase in traffic de- mands. This is driven by the proliferation of electronic devices such as smartphones with a WiFi interface along with their bandwidth intensive applications. Moreover, in the near future, sensor devices that form the Internet of Things (IoTs) ecosystem will also add to future traffic growth. One promising approach to meet growing traffic demands is to equip nodes with an In-band-Full-Duplex (IBFD) radio. This radio thus allows nodes to transmit and receive data concurrently over the same frequency band. Another approach to in- crease network or link capacity is to exploit the benefits of Multiple-Input-Multiple- Output (MIMO) technologies; namely, (i) spatial diversity gain, which improves Signal-to-Noise Ratio (SNR) and thus has a direct impact on the data rate used by nodes, and (ii) spatial multiplexing gain, whereby nodes are able to form concurrent links to neighbors

Throughput Maximization in Unmanned Aerial Vehicle Networks

The use of Unmanned Aerial Vehicles (UAVs) swarms in civilian applications such as surveillance, agriculture, search and rescue, and border patrol is becoming popular. UAVs have also found use as mobile or portable base stations. In these applications, communication requirements for UAVs are generally stricter as compared to conventional aircrafts. Hence, there needs to be an efficient Medium Access Control (MAC) protocol that ensures UAVs experience low channel access delays and high throughput. Some challenges when designing UAVs MAC protocols include interference and rapidly changing channel states, which require a UAV to adapt its data rate to ensure data transmission success. Other challenges include Quality of Service (QoS) requirements and multiple contending UAVs that result in collisions and channel access delays. To this end, this thesis aims to utilize Multi-Packet Reception (MPR) technology. In particular, it considers nodes that are equipped with a Successive Interference Cancellation (SIC) radio, and thereby, allowing them to receive multiple transmissions simultaneously. A key problem is to identify a suitable a Time Division Multiple Access (TDMA) transmission schedule that allows UAVs to transmit successfully and frequently. Moreover, in order for SIC to operate, there must be a sufficient difference in received power. However, in practice, due to the location and orientation of nodes, the received power of simultaneously transmitting nodes may cause SIC decoding to fail at a receiver. Consequently, a key problem concerns the placement and orientation of UAVs to ensure there is diversity in received signal strength at a receiving node. Lastly, interference between UAVs serving as base station is a critical issue. In particular, their respective location may have excessive interference or cause interference to other UAVs; all of which have an impact on the schedule used by these UAVs to serve their respective users