Charalambos Linardakis

Bio: Charalambos Linardakis is an academic researcher from National Technical University of Athens. The author has contributed to research in topics: Passive optical network & Multiplexing. The author has an hindex of 5, co-authored 6 publications receiving 107 citations.

Efficient medium arbitration of FSAN-compliant GPONs

Abstract: SUMMARY The steadily rising demand for multimedia and data services, the falling cost and omnipresence of Ethernet and the maturity of passive optical networks (PON) technology, promise to radically change the landscape in the local loop. The heart of a gigabit PON system (recently standardized by FSAN/ITU) is the medium access controller (MAC), which arbitrates access to the upstream link among users with fluctuating traffic demands and effects the multiplexing and concentration policy. At the same time, it has to safeguard the service quality and enforce the parameters agreed in the service level agreements (SLAs) between the users and the service provider. In this paper, a MAC protocol designed to serve any mix of services according to their quality of service (QoS) needs, employing four priority levels along with a high number of logically separate data queues is presented. The architecture and implementation in hardware of a MAC algorithm capable of allocating bandwidth down to a resolution of a byte with QoS differentiation is the focus of this paper. It employs the bandwidth arbitration tools of the FSAN/ITU G.984.3 standard and maps SLA parameters to GPON service parameters to create an efficient, fair and flexible residential access system. Copyright # 2005 John Wiley & Sons, Ltd.

Slotted optical switching with pipelined two-way reservations

Abstract: Optical burst switching is a core architecture designed to reconcile the available optical technology with the increasing burstiness of traffic. However, disappointing performance in terms of high packet loss and/or low system utilization discouraged broader experimental implementations. A method to avoid these losses by first sending over the control channel a short scout packet that simulates the events that the actual burst will experience is proposed in this paper. Once the scout message detects a drop at any intermediate node, it returns back to the source to avert the payload emission and repeat the process. The way the control works results in essential service quality features, i.e., no loss of bursts, no out-of-order emissions, increased efficiency, much reduced delay variation, and graceful throttling of the load respecting the contracted rates

Scheme for performing statistical multiplexing in the optical layer

Abstract: The proliferation of data-centric networks has intensified the research efforts for development of architectures and technologies supporting fast reconfigurable optical networks accommodating any temporal and (or) spatial traffic fluctuations without WDM channel overprovisioning. The novel core network architecture presented in this paper is based on partitioning a meshed network into a number of clusters. Within each cluster the architecture exploits metropolitan area concepts (MACs) to achieve statistical multiplexing gain by transparent transportation of fixed duration slots. These short slots, which are controlled by means of a MAC protocol, are combined to form larger frames that are then exchanged between the clusters. Specific nodes that serve as gateways between clusters undertake the coordination of frame switching and end-to-end routing. Thus, traffic within a particular cluster enjoys reservation-based no-loss transport, while for the communication between clusters either robust two-way reservation schemes or even optical burst switching (OBS) approaches are possible. The end result is an architecture that supports statistical multiplexing within the optical layer with good performance and reasonable complexity.

Implementation of medium access control for interconnecting slotted rings to form a WDM metropolitan area network

Abstract: Feature Issue on Optical Interconnection Networks (OIN) A system of slotted interconnected rings employing a combination of wavelength-division multiple access (WDMA) with time-division multiple access (TDMA) can serve a metropolitan area without electro-optical conversion and buffering of payload except at system entry points The multiple rings overcome the power budget limitations of the single ring extending the reach of the system to even the largest metropolitan areas, the WDM dimension provides flexibility and ease of evolution, and the TDMA dimension offers the efficiency of multiplexing gain particularly under bursty traffic The system control information is transferred on a dedicated wavelength and is processed in the electrical domain at the ring nodes and the hub, which interconnects the rings The algorithms control the access to each ring and the scheduling of slots among the rings, based on explicit reservations, to adapt efficiently to the fluctuating offered load We present the design and hardware implementation of the access control algorithms for such a system built in the framework of the Information Society Technologies (IST) project DAVID (data and voice over DWDM)

Optical burst switching (OBS) - a new paradigm for an optical Internet

Abstract: To support bursty traffic on the Internet (and especially WWW) efficiently, optical burst switching (OBS) is proposed as a way to streamline both protocols and hardware in building the future gener...

Development of Efficient Dynamic Bandwidth Allocation Algorithm for XGPON

Abstract: This paper proposes an efficient bandwidth utilization (EBU) algorithm that utilizes the unused bandwidth in dynamic bandwidth allocation (DBA) of a 10-gigabit-capable passive optical network (XGPON). In EBU, an available byte counter of a queue can be negative and the unused remainder of an available byte counter can be utilized by the other queues. In addition, EBU uses a novel polling scheme to collect the requests of queues as soon as possible. We show through analysis and simulations that EBU improves performance compared to that achieved with existing methods. In addition, we describe the hardware implementation of EBU. Finally we show the test results of the hardware implementation of EBU.

Efficient dynamic bandwidth allocation for FSAN-compliant GPON

Abstract: We suggest an immediate allocation with colorless grant (IACG) method for dynamic bandwidth allocation of a gigabit passive optical network (GPON) system. The suggested method is based on the GigaPON Access Network (GIANT) media access control (MAC) method. The IACG method can assign the transmission bandwidth regardless of the value of a scheduling counter, whereas the GIANT MAC method can assign the transmission bandwidth only when the scheduling counter has a value of 1. Also, unlike the GIANT MAC method, the IACG method utilizes the unallocated remainder of the transmission bandwidth. At the end of scheduling, the IACG MAC method assigns the unallocated remainder to each optical network unit (ONU) with an equal share. Using computer simulations with the self-similar traffic model, we show that the IACG method dramatically outperforms the GIANT MAC method in mean delay and frame-loss rate.

Performance evaluation of XG-PON based mobile front-haul transport in cloud-RAN architecture

Abstract: Time division multiplexing passive optical network (TDM-PON) technologies are viewed as an attractive solution for flexible and cost-efficient mobile front-haul for cloud radio access network (C-RAN) architecture. However, it is a challenge for TDM-PONs to meet the strict latency requirement of mobile front-haul in C-RAN because they use a dynamic bandwidth allocation (DBA) mechanism to manage upstream traffic. The latency issue of TDM-PON based mobile front-haul has been extensively investigated in the literature with particular focus on IEEE TDM-PON (e.g., 10G-EPON). However, ITU TDM-PONs such as XG-PON and XGS-PON have not yet even been explored in the context of mobile front-haul. To cover this gap, we first evaluate the performance of two recently proposed XG-PON-standard-compliant DBAs, namely, group-assured GIANT (gGIANT) and round-robin DBA (RR-DBA), over simulated mobile front-haul traffic. We conclude based on our evaluation that neither RR-DBA nor gGIANT satisfies the delay required for mobile front-haul. Therefore, we propose an optimized DBA known as optimized round-robin (optimized-RR) that support front-hauling over XG-PONs. The performance evaluation of our optimized DBA against gGIANT and RR-DBA shows significant improvement in upstream delay and utilization as well as lower packet loss and jitter for front-haul uplink traffic transmitted via XG-PON in virtualized C-RAN architecture.

An XG-PON module for the NS-3 network simulator

Abstract: 10-Gigabit-capable Passive Optical Network (XG-PON), one of the latest standards of optical access networks, is regarded as one of the key technologies for future Internet access networks. In this paper, we propose and discuss the design and implementation of an XG-PON module for the NS-3 network simulator. The aim is to provide a standards-compliant, configurable, and extensible module that can simulate XG-PON with reasonable speed and can support a wide range of research topics. These include analysing and improving the performance of XG-PON, studying the interactions between XG-PON and the upper-layer protocols, and investigating its integration with various wireless networks.