Last-mile Broadband Access Research Articles

ESAM - Energy Saving Slot Allocation Based Multicast Routing in Wireless Mesh Network

The wireless mesh network is an emerging technology, offering innovative and efficient solutions typically used for last-mile broadband access. Multicasting is a mode of communication that delivers data from a sender to a set of receivers simultaneously in an effective way. This article deals with the problem of assigning synchronized time slots among the forwarded nodes in the multicast group of a wireless mesh network. To solve this problem, we propose a MAC layer solution that developed with snoozing and awaken slot durations for each node to pick the channel at a specific time and during the remaining period, the node will be in an idle state to listen for the packet arrival using Galois estimation. This mechanism divides the available time into slots depends on the demand of the node transmissions and channel availability. During transmission, each node comes to the awaken state and once the transmission completed the node goes to the snoozing state to preserve the energy. The slot allocation is assigned to each node based on the binary track of the span duration and transmission demands. The slot allocation based on multicast packet forwarding technique reduces the energy expense among nodes and supports to balance network communication duration. This shared slot allocation also minimizes the congestion on the network and creates healthier channel usage during communication. The Simulation results show that the proposed approach has achieved a better outcome than previous works in terms of minimum delay and high throughput.

Joint Concurrent Routing and Multi-Pointer Packet Scheduling in IEEE 802.16 Mesh Networks

IEEE 802.16, also known as Worldwide Interoperability for Microwave Access, is a standardization effort carried out by the IEEE to provide last-mile broadband access to end users. The IEEE 802.16 standard supports two medium access control modes--a mandatory point to multipoint mode and an optional mesh mode. In this paper, we propose an asymmetric interference aware routing algorithm and a new multipointer approach in implementing scheduling algorithms for IEEE 802.16 mesh networks. We modify three different centralized scheduling algorithms, fixed scheduling, ordered scheduling and per-slot scheduling using multipointer approach to allow for spatial reuse in IEEE 802.16 mesh networks. Simulation results reveal that fixed scheduling with SR provides the best performance.

System performance analysis of time-division-multiplexing passive optical network using directly modulated lasers or colorless optical network units

As a promising technology for broadband communication, passive optical network (PON) has been deployed to support the last-mile broadband access network. In particular, time-division-multiplexing PON (TDM-PON) has been widely used owing to its mature technology and low cost. To practically implement TDM-PONs, the combination of intensity modulation and direct detection is a very promising technique because it achieves cost reduction in system installation and maintenance. However, the current intensity-modulation and direct-detection TDM-PON still suffers from some problems, which mainly include a high-power penalty, detrimental Brillouin backscattering (BB), and so on. Thus, using directly modulated lasers (DMLs) and colorless optical network units (ONUs), respectively, two intensity-modulation and direct-detection TDM-PON architectures are proposed. Using VPI (an optical simulation software developed by VPIphotonics company) simulators, we first analyze the influences on DML-based intensity-modulation and direct-detection TDM-PON (system 1) performances, which mainly include bit error rate (BER) and power penalty. Next, the BB effect on the BER of the intensity-modulation and direct-detection TDM-PON that uses colorless ONUs (system 2) is also investigated. The simulation results show that: (1) a low-power penalty is achieved without degrading the BER of system 1, and (2) the BB can be effectively reduced using phase modulation of the optical carrier in system 2.

A Study of Bandwidth Measurement Technique in Wireless Mesh Networks

Wireless mesh networks (WMNs) have been proposed as a key technology for next generation wireless networking to provide last-mile broadband access. Here we have given our observation and study for end to-end bandwidth estimation in WMNs. End-to-end Bandwidth Estimation is an important metric for network management and monitoring. It can also improve the effectiveness of congestion control mechanism, audio/video stream adoration and dynamic overlay. In recent years, many techniques have been developed for bandwidth estimation in the wired as well as the last-hop wireless networks, but they under-perform in WMNs. We investigate attributes that can affect the bandwidth estimation in WNMs; we found existing techniques do not consider the effect of attributes like CSMA/CA-based contending traffic and high interference interference that leads to the error full estimation. In this paper, we present an active bandwidth measurement technique called Bandwidth Probe based on the packet dispersion principle. It measures the steady state bandwidth of the system while considering the effects of the FIFO cross and CSMA/CA-based contending traffic. It is also mitigating the effect of interference. We also show how to achieve the stationary state behaviour of the system to limit the number of probe packets. On simulation, Bandwidth Probe gives a accurate estimation of the available bandwidth using average convergence time and lower intrusiveness.

Modified WRR Scheduling Algorithm for WiMAX Networks

Worldwide Interoperability for Microwave Access (WiMAX), which is also known as 802.16 standard, supports last-mile broadband access wireless networks. WiMAX has many advantages including wide coverage area and high bandwidth. These advantages enable WiMAX to support long transmission range and high data rate compared to cellular and WiFi network. WiMAX technology uses a number of scheduling techniques in the Medium Access Control (MAC) layer, which is responsible for the utilization of available resources in the networks and distribute them among users in order to ensure the desired quality of service. In this study, we propose a Modified Weighted Round Robin (MWRR) scheduler in order to decrease the average end-to-end delay and improve the average throughput. The proposed scheduling technique has been designed and simulated using the QualNet 5.0.2 network simulator. In order to evaluate the performance of our proposed approach, we compared our results to the results of well-known scheduling techniques (weighted Round Robin (WRR), Strict Priority (SP), and Weighted Fair Queuing (WFQ)). The average percentage of improvement was around 4%.

DMesh: Incorporating Practical Directional Antennas in Multichannel Wireless Mesh Networks

Wireless mesh networks (WMNs) have been proposed as an effective solution for ubiquitous last-mile broadband access. Three key factors that affect the usability of WMNs are high throughput, cost-effectiveness, and ease of deployability. In this paper, we propose DMesh, a WMN architecture that combines spatial separation from directional antennas with frequency separation from orthogonal channels to improve the throughput of WMNs. DMesh achieves this improvement without inhibiting cost-effectiveness and ease of deployability by utilizing practical directional antennas that are widely and cheaply available (e.g., patch and yagi) in contrast to costly and bulky smart beamforming directional antennas. Thus, the key challenge in DMesh is to exploit spatial separation from such practical directional antennas despite their lack of electronic steerability and interference nulling, as well as the presence of significant sidelobes and backlobes. In this paper, we study how such practical directional antennas can improve the throughput of a WMN. Central to our architecture is a distributed, directional channel assignment algorithm for mesh routers that effectively exploits the spatial and frequency separation opportunities in a DMesh network. Simulation results show that DMesh improves the throughput of WMNs by up to 231% and reduces packet delay drastically compared to a multiradio multichannel omni antenna network. A DMesh implementation in our 16-node 802.11b WMN testbed using commercially available practical directional antennas provides transmission control protocol throughput gains ranging from 31% to 57%

Challenges in Optical Wireless Communications

Optical wireless technologies have been incorporated into millions of consumer products such as televisions and cell phones, and they also enable last-mile broadband access, inter-satellite links and deep space connections. This article highlights the challenges that engineers and researchers face as they develop new applications and methods to improve this technology.

Optical wireless communication networks for first- and last-mile broadband access [Invited

"http://www.osa-jon.org/features/OAN_2005.html". Feature Issue on Optical Access Networks (OAN). We review the progress in optical wireless communication networks for first- and last-mile broadband access. The link budget is discussed. Modulation and coding are studied to deal with the atmospheric turbulence channel. Topics related to efficient topology design, survivable routing, and dynamic reconfiguration algorithms are discussed. It is shown that optical wireless communication networks have great potential to provide enough bandwidth for first-mile broadband applications. However, major challenges need to be overcome in pointing and acquisition, coding, and network design to make optical wireless networks more popular with customers.