Cambridge Core – Communications and Signal Processing – FiWi Access Networks – by Martin Maier. The evolution of broadband access networks toward bimodal fiber-wireless (FiWi ) access networks, described in this book, may be viewed as the endgame of. This article provides an up-to-date survey of hybrid fiber-wireless (FiWi) access networks that leverage on the respective strengths of optical.

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Because of the explosive growth of smart devices such as smart phones and sensors, the number of such devices has also grown phenomenally that require real time communication accesx quality of service QoS -centric applications for CPSs, such as smart grid, medical, and traffic control systems, which construct smart society. To deal with such situations, the FiWi access networks may be a suitable choice since they are capable of providing both wide bandwidth and flexibility.

Therefore, the QoS of real time communication degrades significantly.

Through computer-based simulations, we demonstrate that our proposed scheme can significantly improve the QoS performance of the FiWi access networks for CPSs.

In addition, due to the development of smart and portable devices e. By utilizing the wireless networks to interact among cyber and physical components, CPSs can improve many smart systems such as smart grid, medical, and traffic control systems which construct smart society.

Although the development of wireless techniques gives us fascinatingly convenient communication facilities, the network capacity of the backhaul networkd will gradually, if not drastically, diminish as it is not enough to meet the demands of the accwss users, number of whom has been increasing by leaps and bounds.

In order to deal with such a mass users demands, the optical network is considered by many researchers to be suitable for the backhaul network because it is capable of providing stable communication and huge bandwidth. Therefore, the Fiber-Wireless FiWi network [4][5]which integrates optical networks and wireless access networks attract more attention for supporting next generation CPSs in a future ubiquitous network. In this network, we can construct a WLAN flexibly because the AP can be conveniently set without any complex design such as deployment of base stations in cellular networks.

Also, the PON provides a wide bandwidth and stable communication with low power consumption since it uses passive devices flwi with power saving schemes. Due to these features, the FiWi accses be considered to be an attractive technology to meet the high bandwidth requirement of the viwi increasing number of mobile users and sensors for Networsk.

A critical shortcoming of such a FiWi network is its transmission latency, which can seriously affect the QoS of real time communications. As a consequence, a transmission latency occurs in the ONU. This transmission latency causes degradation of QoS for real time communications, e.

In other words, they do not operate in a synchronized fashion, and contributes to the acccess latency, which severely degrades the QoS. The remainder of this paper is organized as follows. Also, in the work conducted by Suzuki et al. Their proposal was based upon a utility-based resource allocation scheme comprising two stages. In the first stage, the user assignment among the base stations is determined which is followed by an estimation of tentative slot allocations such that the entire system throughput over all the APs is increased.

The second fwii is independently conducted in each of the APs to increase the system utility by exchanging slots among the users within the same AP. By this way, Suzuki et al. Bandwidth allocation related research work have been carried out by other prominent researchers also.

Netwoeks this way, it improves a number of QoS parameters, such as the network throughput, latency, and bandwidth utilization. On the other hand, routing algorithms for the wireless side were investigated in the work conducted by Sarkar et al.

The investigation from that work reported that the Risk-And-Delay-Aware Routing accexs RADARin contrast with other routing protocols in the wireless side, exhibits the best QoS performance in terms of throughput, latency, and load balancing. The work enumerates a number of important research challenges in FiWi environments, namely integrated channel assignment and bandwidth allocation, combined path selection, end-to-end QoS support, and so on.


It was also shown in that work that deploying hierarchical frame aggregation across EPON and WLAN-based mesh networks substantially enhances the throughput-delay performance. A new framework was presented networkss meet strict and diverse QoS requirements over FiWi networks in [16]. The framework exploits the available resources in the considered FiWi networks. Future directions on designing an advanced DBA were also given in [16] for enabling a proactive admission policy for FiWi networks while meeting the QoS requirements of the users.

The trade-off between energy saving and QoS support for multi-media content delivery in FiWi broadband access networks was investigated in [17]. Also, a green QoS differentiated routing scheme was proposed in [17] showing that there are different ways of meeting QoS demands in FiWi networks.

Furthermore, the research conducted in [18] also attests to the benefit of adopting FiWi access networks as they bring great prospects for energy savings in addition to cost-effective solutions. It is worth mentioning that the research in [18] highlights the following important point. The flexibility of FiWi networks in terms of energy saving becomes useful only if the QoS experienced by the users can be kept at acceptable levels. For instance, more communication hops can lead to increase in delay and decrease in throughput, and this QoS degradation may be noticed particularly in the wireless segment of a FiWi network.

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A broader trend in the need to satisfy the QoS requirements of FiWi network users is delineated in the work in [19]. The work demonstrates how low cost EPONs and wireless mesh networks can be combined to facilitate the communication of smart power grid systems. As a solution, an adaptive admission control technique to provide QoS support for FiWi smart grid acxess networks was proposed in [19]. First, acccess QoS control technique of the As a standard of the original Depending on the need of the WLAN users i.

An advantage of EDCA is that it can be implemented in devices at a reasonably low cost because of its simple control. However, QoS parameters such as bandwidth, delay and jitter cannot be guaranteed accurately in EDCA since it ciwi just a priority based control. Also, when the high priority data occupy the whole network transmission, the priority control offered by EDCA may not function adequately. Ceiling function is applied to the division result in order to ensure the maximum number of frames, which the STA can transmit.

The entire process is shown in Fkwi. On the other hand, the GATE frame directs the amount of traffic the OLT has allowed to transmit, along with the beginning time to transmit, to every ONU in order to avoid metworks in the upstream traffic.

As a consequence, the responsiveness toward the arrival traffic is low in this scheme. In case the ONU has no accesz to transmit, it sends idle frames during the excess allocation it receives networkw shown in Fig.

Thus, it causes transmission latency to a part of the data which is not transmitted during the allocation. Moreover, also the excess bandwidth allocation increase the transmission latency of the data from other ONUs.

In summary, while the utilization efficiency of bandwidth and responsiveness of these two schemes i. According to the behavior of the Nehworks The fixed latency refers to the duration between a reported frame and the transmitted frame.

On the other hand, the variable latency indicates the duration between the arrived traffic and the reported traffic. Equation 5 shows that the factor of increasing the transmission latency is the length of DBA period also known as the DBA cycle.

As explained in the earlier section, the existing DBA methods are not efficient because these methods cannot be used together with the utilization efficiency of the netqorks and responsiveness for decreasing the transmission latency in the ONU. The main netowrks why the existing DBA methods are inefficient is that the arrival traffic toward the ONU cannot be accurately predicted.

So, we propose an efficient DBA scheme for decreasing the transmission latency in the ONU with high utilization efficiency of bandwidth. After finishing the QoS negotiation, the AP begins the scheduling part. Here, we discuss the availability of this process from the point of view of overhead during the process.


In general, the duration time of SI is significantly longer than that of netwoks DBA period, which means that the process is not executed so frequently. Therefore, the HCCA collection is available because the effect of the overhead is quite neteorks. In this section, we evaluate the nefworks of our proposal through extensive computer simulation programed in Ruby.

The simulation parameters are summarized in Table I. We suppose that the FiWi access network has enough bandwidth for providing the requested bandwidth from the ONU because sufficient bandwidth is needed to meet the QoS demands of the real time QoS. TM-DBA has a factor for allocating bandwidth ranging from 1 to 3.

The performance comparison is conducted in terms of the efficiency of bandwidth utilization, transmission delay, and usage of buffer in the ONU.

We set the length of DBA cycle to 0. On the other hand, according to the size of the allocation factor, the efficiency of bandwidth utilization in TM-DBA tends to worsen.

These results show that our proposal achieves superior performance regardless of the length of the DBA cycle. To solve this problem, in this paper, we proposed a QoS control scheme, which allows cooperation between the WLAN and PON in order to achieve both bandwidth efficiency and responsiveness.

The results of our conducted simulations demonstrate that our proposal can significantly improve various QoS parameters for real time communications for CPSs in contrast with existing methods. Thus, our proposal can be considered to be an effective QoS control method in QoS adaptive networks for CPSs such as FiWi access netwworks comprising heterogeneous network technologies.

An ONU buffers the upstream traffic. Proposed Scheme As netwotks in the earlier section, the existing DBA methods are not efficient because these methods cannot be used together with the utilization efficiency of the bandwidth and responsiveness for decreasing the transmission latency in the ONU.

Simulation Environment In this section, we evaluate the performance of avcess proposal through extensive computer simulation programed in Ruby. Fadlullah S’06—M’11 received the B. His current research interests include smart grid, network security, intrusion detection, and quality of security service provisioning mechanisms.

Hiroki Nishiyama received his M. He is a young, yet already prominent, researcher in his field as evident from his valuable contributions in terms of many quality publications in prestigious IEEE journals and conferences. He received the Best Student Award and Excellent Research Award from Tohoku University for his phenomenal performance during the undergraduate and master course study.

His research covers a wide range of areas including traffic engineering, congestion control, satellite communications, ad hoc and sensor networks, and network security.

Yuichi Kawamoto received his B. Currently, he is pursuing the M. He is a recipient of Japan Society for the Promotion of Science in His research interests are in the areas of satellite networks and sensor networks. He received his B.

Cooperative QoS Control Scheme Based on Scheduling Information in FiWi Access Network

Inhe joined NTT, where he has been engaged in the research and development of optical access systems. His current research interests include dynamic bandwidth allocation and dynamic sleep scheduling for energy efficient access systems. He received the B.

Inhe joined NTT Laboratories, on research and development of optical communication systems, including passive optical network PON based optical access systems. Sincehe has been working for IEEE Naoto Yoshimoto received the B.

He joined NTT Corporation, Kanagawa, Japan, inand mainly engaged in the research and development of optical transmission systems and devices for broadband access systems. His current research interests include the planning of next-generation optical-wireless converged diwi networks and architectures.

He has been the Visiting Professor with Hokkaido University since