Design Methodology for Wireless Backhaul/Fronthaul Using Free Space Optics and Fibers (original) (raw)
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Free-Space Optical Gateway Placement in Hybrid Wireless Mesh Networks
IEEE/OSA Journal of Lightwave Technology, 2009
The capacity of wireless mesh networks (WMN) must usually be upgraded as usage demands evolve over time. This is normally done by adding gateways which serve to increase the backhaul capacity of the network. In this paper we consider adding capacity in this manner using free-space optical (FSO) backhaul links. To accomplish this, we formulate a joint clustering and gateway placement problem which includes the strong rate-distance dependence of practical FSO links. The formulation incorporates the positions of existing wireline gateways and minimizes the number of additional hybrid-FSO/RF gateways which are needed to satisfy the target capacity requirements. After showing the complexity of the problem, a solution that is motivated by genetic algorithms is proposed. The performance of our algorithm is then compared to an optimal solution generated via an integer linear program (ILP) for small WMNs. The proposed algorithm is then modified to allow for balancing the traffic load that is carried by each gateway in the WMN. Many scenarios are considered which demonstrate the value of using FSO backhaul links to obtain post-deployment capacity upgrades in response to changes in user traffic.
BACKHAUL PERFORMANCE OF 5G TWDM-PON NETWORK USING ENERGY EFFICIENT CLUSTERING
Dense deployment of small cells are required to provide high capacity and universal access to the future next generation (5G) mobile networks. These 5G networks require cost-effective and reliable backhaul connectivity between small cells. Time and Wavelength Division Multiplexed Passive Optical Networks (TWDM-PONs)are considered as an efficient choice to serve the above purpose. The cost minimized design of a backhaul network for a 5G mobile system using TWDM-PON is presented. Deployment and equipment costs are considered and the design should be able to satisfy network constraints such as the maximum number of subscribers per optical terminal and maximum number of subscribers per wavelength. Considering the fact that many small cell base stations are dispersed over an extensive wireless coverage, an Energy Efficient clustering algorithm is proposed for the optimal solution. Moreover useful strategies like using multistage remote nodes and cable conduits are applied to further reduce the labor cost of trenching and laying fibers. Results show that the proposed research work can substantially reduce the backhauling cost when compared with the traditional K-means clustering algorithm and other clustering approaches.
Fronthaul Design for Wireless Networks
Applied Sciences
Cloud Radio Access Network (C-RAN) architectures have arisen as an alternative to traditional wireless network architectures, notably by taking advantage of the functional split between the multiple distributed Remote Radio Heads (RRHs) and the centralized Baseband Units (BBUs), through the creation of a new connectivity segment—the fronthaul. In order to maximize the investment return, it is important to find out, for this C-RAN segment, which technologies provide cost-effective solutions. This paper addresses this issue by evaluating and comparing the performance of Microwave Radio Transmission (MRT), Free Space Optics (FSO), and Fiber Optics (FO) technologies when applied to the fronthaul. First, a methodology is provided to determine the most cost-effective solution for each RRH–BBU link, as well as to compute the required number of BBUs and where they should be positioned in order to minimize the overall network costs. Next, a cost-effectiveness comparison of the aforementioned...
A splitter location–allocation problem in designing fiber optic access networks
European Journal of Operational Research, 2011
This paper deals with a physical access network design problem of fiber-to-the-home passive optical network (FTTH-PON). The design of FTTH-PON access network seeks the cost effective location of optical splitters that provide optical connectivity from central office to subscribers in a given service area. We formulate the problem as a multi-level capacitated facility location problem on a tree topology with nonlinear link cost. Dealing with the nonlinear link cost, we propose an objective function relaxation approach to obtain tight upper and lower bounds. We develop valid inequalities that enhance the lower bound and propose a local search heuristic procedure that improves the upper bound. Valid inequalities force integrality condition on the number of splitters placed at nodes. Local search heuristic improves the initial greedy solution by placing splitters on the sub-root nodes of a given tree network. Computational results demonstrate the effectiveness of the proposed solution procedures.
Optical splitters configuration for long-reach passive optical network deployment
Proceedings of the 2013 18th European Conference on Network and Optical Communications & 2013 8th Conference on Optical Cabling and Infrastructure (NOC-OC&I), 2013
In this paper, we examine a nation-wide deployment case study of 1024-way-split Long-Reach Passive Optical Network (LR-PON) for Ireland. We analyse the effect that different splitters configurations in the Optical Distribution Network have on the PONs utilisation and on the total fibre cable length required to cover the country. Our approach, which considers both dense and sparsely populated areas, is based on a clustering algorithm that, starting from the location of end users, aggregates them into clusters, representing different branches of a PON. Our test scenarios are generated from a real dataset containing exact positions of millions of buildings. Our results show how the optimal dimensions and positions of the power splitters vary when we move from densely populated to sparsely populated ares.
Designing Least-Cost Survivable Wireless Backhaul Networks
Journal of Heuristics, 2000
This paper presents a new heuristic algorithm for designing least-cost telecommunications networks to carry cell site traffic to wireless switches while meeting survivability, capacity, and technical compatibility constraints. This requires solving the following combinatorial optimization problems simultaneously: (1) Select a least-cost subset of locations (network nodes) as hubs where traffic is to be aggregated and switched, and choose the type of hub (high-capacity DS3 vs. lower-capacity DS1 hub) for each location; (2) Optimally assign traffic from other nodes to these hubs, so that the traffic entering the network at these nodes is routed to the assigned hubs while respecting capacity constraints on the links and routing-diversity constraints on the hubs to assure survivability; and (3) Optimally choose the types of links to be used in interconnecting the nodes and hubs based on the capacities and costs associated with each link type. Each of these optimization problems must be solved while accounting for its impacts on the other two. This paper introduces a short term Tabu Search (STTS) meta-heuristic, with embedded knapsack and network flow sub-problems, that has proved highly effective in designing such "backhaul networks" for carrying personal communications services (PCS) traffic. It solves problems that are challenging for conventional branch-and-bound solvers in minutes instead of hours and finds lower-cost solutions. Applied to real-world network design problems, the heuristic has successfully identified designs that save over 20% compared to the best previously known designs.
IEEE Access, 2020
5G networks have arrived and are able to shift paradigms within the areas of connectivity, maintainability, scalability and availability. Their aim is to ensure that users can remain online with their devices at any time and in any place. In light of this, solutions for centralized networks are becoming attractive since they are manageable and low-cost. In these conditions, the use of computing techniques such as fuzzy logic benefits the supervision and planning of networks by optimizing and controlling resources as well as managing the system. However, planning a centralized network tends to raise challenges in the optical sectors that are located between the telecommunications center and the base station. Technologies such as radio over fiber are being examined to meet the demands in the fronthaul market, although they raise many other challenges. For this reason, in this study, we have adopted an intelligent strategy to determine in a balanced way which radio over fiber signals should be allocated in the optical sector. This strategy is implemented using fuzzy logic and may be used in decision making to plan the future of centralized networks. The results show that it is possible to make tradeoffs between the capital expenditure and performance of the system.
Optimized Design of Multistage Passive Optical Networks
Journal of Optical Communications and Networking, 2012
The large investments required for deploying passive optical networks (PONs) render the disposal of appropriate planning tools for designing such networks in a cost-effective way a necessity. This paper addresses the problem of finding the least costly tree topology time-division multiplexing PON (TDM-PON) deployment configurations considering equipment and installation costs (CAPEX) and operational exploration costs. With this purpose, an integer linear programing model is developed, which is capable of designing not only common single-stage PON configurations, but also PONs with multiple stages of optical splitting. In order to reduce the computation time for problems of larger size, a two-stage heuristic is also proposed. The simulation results for the cases studied reveal that an optimal multistage splitting strategy can lead to cost savings of up to 15% in CAPEX expenditures in comparison with the traditional single-stage approach. Furthermore, the heuristic procedure proposed is shown to obtain results within acceptable bounds relative to the optimum solutions, hence validating its use for larger sized networks. The results also show that the average CAPEX cost savings between the two-stage and single-stage approaches are quite dependent on the strategies used to choose candidate locations for the splitters, with values ranging from 5 to 12% depending on whether random candidate placement or k-means-based placement is used.
Characterizing node availability and connectivity of a hybrid optical/RF wireless network
2000
The performance of wireless nodes configured with hybrid free space optical (FSO) and radio-frequency (RF) links is analyzed in this thesis. The main objective was to determine the number of hybrid links that were required at each node of the wireless network, so that specified availability metrics would be met. To model the random occurrence of link outages each FSO and RF link configured at network terminal was represented by a two state on-off Markov chain with independent state transitions. Using the duty cycle of the hybrid link as the characterizing parameter, it was shown that atleast four hybrid link pairs would be required to achieve 99% availability of atleast one RF link capacity for duty cycles greater than 50%. To ensure 99% availability of atleast one FSO link capacity, the FSO channel must exhibit duty cycles greater than 0.7. Using two state approximation of a multiterminal node, the blocking, delay and throughput analysis for multihop transmission has also been presented. Analytical expressions derived for the buffer occupancy show its explicit dependence of the average off duration of the hybrid channel. Both first and second moments of buffer occupancy tend to be higher than that found for