George Kalfas

Saturation Throughput Performance Analysis of a Medium Transparent MAC Protocol for 60 GHz Radio-Over-Fiber Networks

We demonstrate an analytical model for calculating the saturation throughput performance of a medium transparent medium access control (MAC) protocol in 60 GHz radio-over-fiber (RoF) networks. The proposed model incorporates effectively the medium transparent MAC mechanism, assuming a finite number of terminals and ideal channel conditions. It takes into account contention both at the optical and wireless layer, ensuring seamless and dynamic capacity allocation over both transmission media. This model enables extensive saturation throughput performance analysis for the medium transparent MAC and has been applied to 60 GHz RoF network scenarios considering variable numbers of available optical wavelengths, wireless nodes and serving antenna elements and for two different data rate values, namely 155 Mbps and 1 Gbps. Comparison between the model-based throughput results and respective simulation-based outcomes reveals that our model is extremely accurate in predicting the system throughput. Moreover, it confirms that the proposed medium transparent MAC protocol can effectively operate in high-speed 60 GHz RoF LAN environments.

Client-weighted medium-transparent MAC protocol for user-centric fairness in 60 GHz radio-over-fiber WLANs

We present a novel client-weighted mediumtransparent medium access control (CW-MT-MAC) protocol with enhanced fairness service delivery properties accompanied by a low-loss remote access unit (RAU) architecture for use in indoor, Gbps-capable, 60 GHz radio-over-fiber (RoF) wireless local area networks (WLANs). Our approach relies on incorporating a client-weighted algorithm (CWA) in the optical capacity allocation mechanism employed in the MT-MAC scheme, so as to distribute the available wavelengths to the different antenna units according to the total number of active users served by each individual antenna. The protocols throughput and delay fairness characteristics are evaluated and validated through both simulations and analytic modeling for saturated network traffic operational conditions. In addition, extended simulation-based performance analysis for nonsaturated network conditions and for different end-user distributions, traffic loads, and available optical wavelengths at 1 Gbps data rates is presented. Our results confirm that complete throughput equalization can be achieved even for highly varying user population patterns when certain wavelength availability conditions are satisfied. At the same time, the presented scheme manages to equalize the average packet delays amongst packets generated by all RAUs while concurrently dropping the packet delay variation metric that is essential for quality of service delivery. Finally the proposed RAU design reduces insertion losses by almost 14 dB compared to RAU elements used in MT-MAC-compatible bus networks, extending in this way the number of supported RAUs by an order of magnitude and enabling the formation of extended-reach, high-speed RoF WLANs.

Towards medium transparent MAC protocols for cloud-RAN mm-wave communications over next-generation optical wireless networks

The 60 GHz millimeter-wave band remains the only unlicensed, high-capacity spectral zone which is however limited to Personal Area Networks due to its picocellular nature. Facilitating mm-wave communication onto Radio-over-Fiber infrastructures alleviates the picocellular range handicap while it offers multi-Gbps wireless connectivity. In light of the above we report on the performance of a combined PON-plus-802.11ad network, showing for the first time the interplay capabilities of both standards towards forming extended reach 60 GHz WLANs. We obtained simulation-based throughput and delay measurements both for pure 802.11ad and hybrid PON-plus-802.11ad networks, addressing the dependence of the consolidated architecture on the load, the wireless packet payload and the percentage of intra-Access Point to Internet-destined traffic. Finally, we present a network platform that hosts functional and physical consolidation of the Medium-Transparent MAC (MT-MAC) 60 GHz WLANs with Fiber-Wireless architectures supporting Cloud Radio Access Networks (C-RAN) in order to create robust, versatile and ultra-fast next generation networks.

Very High Throughput 60GHz wireless enterprise networks over GPON infrastructure

We present our findings regarding the deployment of 60GHz Gigabit WLAN RoF enterprise networks operating under Medium Transparent-MAC protocols over existing GPON infrastructures. Two possible network scenarios are investigated: i) the GPON-plus-RoF approach considering the 60GHz RoF bus WLAN connected to a conventional GPON ONU, and ii)the RoF-over-PON, which fuses the GPON OLT with the MT-MAC Access Gate at the same Central Office (CO). Simulation-based throughput and delay results are obtained for both network scenarios, revealing the dependence of the 60GHz enterprise network performance on several network planning parameters such as the number of optical wavelengths being available to the enterprise network, the GPON dedicated bandwidth, the load of the enterprise network as well as the percentage of inter- and intra-LAN traffic, highlighting in each case the prevailing architecture.

Network planning for 802.11ad and MT-MAC 60 GHz fiber-wireless gigabit wireless local area networks over passive optical networks

We present a study concerning the network planning of 60 GHz gigabit wireless local area networks (WLANs) over existing passive optical network (PON) infrastructures. Two fiber-wireless configurations for gigabit WLAN network formations are investigated: (i) the Radio & Fiber (R&F) approach that considers several 802.11ad access points connected to conventional gigabit passive optical network (GPON) optical network units, henceforth termed as the GPON-plus-802.11ad approach; and (ii) the Radio-over-Fiber (RoF) paradigm that employs several remote access units operating under the medium-transparent MAC (MT-MAC) protocol, hence termed as the MT-MACover- PON approach. Simulation-based throughput and delay results are obtained for both network scenarios, revealing the dependence of the 60 GHz enterprise network performance on several network-planning parameters such as load, traffic shape, number of optical wavelengths in the backhaul, and optical backhaul fiber length, highlighting in each case the prevailing architecture. Based on the respective findings we also study a hybrid multitier architecture, termed the GPON-plus-MT-MAC approach, that fuses the abilities of both the RoF and R&F architectures in order to optimally combine their properties and set a framework for next-generation 60 Ghz fiber-wireless networks.

Optical Physical-Layer Digital Network Coding for 2.5-Gb/s RoF-Based FiWi Networks

We demonstrate the first digital optical physical-layer network coding (OPNC) scheme for 2.5-Gb/s ON/OFF keyed (OOK) subcarrier modulated (SCM) signals suitable for the application in fiber-wireless networks. The proposed OPNC scheme employs all optical XOR logic gates that rely on cross-phase modulation-based Semiconductor Optical Amplifier (SOA) Mach-Zehnder interferometers to perform encoding and decoding operations. The proposed encoding and decoding scheme is targeting deployment at the central office and the clients site at the remote antenna units, respectively. Proof of concept verification is experimentally demonstrated for 2.5-Gb/s OOK-SCM data using a 10-GHz subcarrier. Both synchronous and asynchronous operations are evaluated, achieving error free operation.

A Radio-Over-Fiber network with MAC protocol that provides intelligent and dynamic resource allocation

We demonstrate a Radio-Over-Fiber network equipped with an intelligent Medium Transparent Access Control protocol for dynamic wavelength assignment to Remote Access Units.

Non-Saturation Delay Analysis of Medium Transparent MAC Protocol for 60 GHz Fiber-Wireless Towards 5G mmWave Networks

In this paper, we demonstrate an analytical model for computing the end-to-end packet delay of a converged optical/wireless 60 GHz Radio-over-Fiber (RoF) network operating under the medium-transparent MAC (MT-MAC) protocol. For the calculation of the cycle times, this model considers the protocol time consumed for contention and data exchange over both optical and wireless media, a feature of the MT-MAC that effectively enables it to provide direct and seamless interaction between the RoF Central Office and the end users. This new analytical model enables us to conduct an extensive delay performance analysis of the various performance aspects of hybrid RoF networks operating under the fixed service paradigm, such as various optical capacity availability scenarios, varying load conditions, optical network ranges, transmission window lengths, and data packet sizes. The derived theoretical results present an excellent match with the respective simulation findings, providing sub millisecond latency values for a plethora of network conditions, confirming that the MT-MAC scheme can effectively be incorporated into the upcoming mm-wave 5G era.

Performance Analysis of a Medium-Transparent MAC Protocol for 60GHz Radio-over-Fiber Networks

We demonstrate for the first time an analytical model for computing the saturation throughput of a Medium-Transparent MAC protocol in 60GHz Radio-over-Fiber networks, assuming a finite number of terminals and ideal channel conditions. The model takes into account contention both at the optical and the wireless layer, effectively incorporating the Medium-Transparent MAC mechanism for seamless and dynamic capacity allocation over both optical and wireless transmission media. Based on this model, we provide an extensive saturation throughput performance analysis of the Medium Transparent MAC protocol for various optical capacity availability scenarios and different numbers of wireless users. The theoretical results are found to be in good agreement with respective simulation-based findings, confirming that the employment of Medium Transparent MAC protocols can allow for efficient extended LAN operation of 60 Radio-over-Fiber networks.

Delay Analysis of Converged Medium Transparent Fixed Service Optical-Wireless Networks

We demonstrate for the first time an analytical model for computing the end to end packet delay of an Optical/Wireless 60GHz Radio-over-Fiber (RoF) network operating under the Medium-Transparent MAC (MT-MAC) protocol. The model takes into account contention both at the optical and the wireless layer, effectively incorporating the MT-MAC mechanism for seamless and dynamic capacity allocation over both optical and wireless transmission media. Based on this model, we provide an extensive delay performance analysis of the Medium Transparent MAC protocol for various optical capacity availability scenarios, varying load conditions and optical network fiber lengths. The theoretical results are found to be in good agreement with respective simulation-based findings, confirming that the employment of Medium Transparent MAC protocols can allow for efficient incorporation of the MT-MAC scheme into the upcoming era of 5G mm-wave small-cell networks.