3.1. Overview of the algorithm
Our approach aims at dynamically adjusting and ﬁlling up the DL/UL sub-frames in TDD mode, while each sub-frame is further allocated to service queues of different QoS requirements such as latency, priority and fairness. Slots in a frame can carry different amount of data owing to the MCS in PHY, and the varying data rate may further affect how bandwidthallocation is performed. Based on the above characteristics, the HUF is proposed to well utilize the bandwidth. An urgency parameter which considers three met- rics, namely latency in terms of deadline, fairness in terms of num- ber of requested slots and priority of service ﬂows, is used to decide the servicing order of all data/requests. The deadline repre- sents the number of frame durations left before an uplink request or a downlink packet must be served. A request having a deadline equaling to one must be dispatched in this frame so as to satisfy the latency requirement. The other two contribute to the urgency in terms of the urgency factor, i.e. U-factor, in which a higher value indicates a more urgent request. While the priority is trivial as being a metric, the rationale behind the employment of number of requested slots is that, requests demanding large amount of bandwidth shall be allocated as early as possible. They are rela- tively hard to be scheduled compared to requests of small amount and therefore tend to miss the deadline.
Abstract—The mobile WiMAX systems based on IEEE 802.16e-2005 provide high data rate for the mobile wireless network. However, the link quality is frequently unstable owing to the long-distance and air interference and therefore impacts real-time applications. Thus, abandwidthallocationalgorithm is required to be modulation-aware, while further satisfying the latency guarantee, service differentiation and fairness. This work proposes the HighestUrgencyFirst (HUF) algorithm to conquer the above challenges by taking into consideration the adaptive modulationand coding scheme (MCS) and the urgency of requests. Downlink and uplink sub-frames are determined by reserving the bandwidthfor the most urgent requests and proportionating the remaining bandwidthfor others. Then, independently in the downlink and uplink, the HUF allocates bandwidth to every mobile station according to a pre-calculated U-factor which considers urgency, priority and fairness.
The proposed admission control scheme calculates the admission condition based on different kinds of MCS and minimum reserved rate requirements. The modulationaware scheduling algorithmandbandwidthallocation scheme can allocate bandwidth more efficiently in the finite frame duration and guarantee the minimum quality of service (QoS) requirements to each admitted connection by translating the QoS requirements into time slots. Finally, our simulation results show that the proposed scheduling solution can improve the throughput of the entire network and guarantee the minimum QoS requirements to each admitted connection.
The IEEE 802.16 mesh mode MAC supports centralized scheduling and distributed scheduling. In this paper, we adopt centralized scheduling. With centralized scheduling, every mesh subscriber station (SS) sends its resource requests to mesh base station (BS), and the mesh BS determines the amount of bandwidth allocated to each link. Route construction and packet transmission scheduling are the main design issues of wireless mesh networks. The main idea of route construction is to build a delivery tree from BS to all SS. The main idea of packet scheduling is to determine the active links for transmitting packets during each scheduling timeslot. Both design issues have great impact on network bandwidth utilization. However, it has been proven that the routing and packet scheduling problem in wireless mesh networks is an NP-Hard problem, which means that when the number of SS nodes in a wireless mesh network is large, it is infeasible to find the optimal routing and packet scheduling.
Abstract—In this article, abandwidthandlatencyaware con- tribution estimation (BLACE) mechanism is proposed to enhance the efficiency of content distribution in a mesh peer-to-peer (P2P) streaming system. This is because the mesh P2P streaming system outperforms others in many aspects, but most content distribution mechanisms use only one of upload bandwidthand link latency as a factor, several contribution-aware schemes (CASs) just punish selfish peers, and some CASs only rearrange the content receiving order. Hence, the BLACE proposes a prevention way considering every peer’s upload bandwidth, link latency, and the maximum playing delay of a stream at the same time to prioritize the content distribution. Moreover, BLACE is implemented on Coolstreaming with NS2 and experimental results show that BLACE could at the most shorten the receiving time about 15.44%, 13.94%, and 8.26%, and improve the whole performance about 7.05%, 2.81%, and 2.69% at the most, when it compares with the Coolstream- ing, the Coolstreaming with bandwidth preference, and the Cool- streaming with latency preference, respectively.
A. Related Works
Much research has been devoted to adaptive video stream- ing. The goal of adaptive streaming is to dynamically adjust the content of video streams to handle the variation of different resource constraints imposed by networks and user devices, such as network bandwidthand transmission power/display capability/computing speed of user devices. According to the video format employed, the techniques for adaptive streaming can be classified into three categories: scalable coding, video transcoding, and stream replication. Scalable coding can be further divided into three sub-categories: layered coding, FGS coding, and multiple description coding (MDC). With layered coding, a video sequence is encoded into one base stream and multiple enhancement streams. While the base stream can provide the basic visual quality, the enhancement streams can improve the visual quality in a progressive way. Many streaming techniques for layered coded streams can be found in the literature [16-19]. In , the authors studied a layered video multicast system over wired and wireless networks, and proposed a joint bandwidthand forward error correction (FEC) allocation scheme for layered streams to optimize the overall video quality, subject to a certain loss rate requirement. In , a dual-plan bandwidth smoothing scheme was proposed by taking advantage of the signal-to-noise ratio (SNR) scal- ability of layered coding. When the renegotiation fora new transmission bit rate fails, the proposed scheme can adaptively discard certain enhancement layers to guarantee continuous video playback at the original frame rate.
heavily loaded ONUs in each transmission cycle, thus improving the performance of the limited allocation scheme. In addition, also addressing the idle time issue, the authors proposed an early allocation mechanism, called DBA2, which schedules a lightly loaded ONU without delay, whereas it schedules heavily loaded ONUs after the OLT receives all REPORT messages and performs computation forbandwidthallocation. However, the DBA2 algorithm improves the idle period only under light or medium trafﬁc loads. Moreover, most of the ONUs may have abandwidth demand larger than the minimum guaranteed bandwidth under high trafﬁc loads, so the GATE message cannot be transmitted early to the ONU for idle time compensation. In 2006, Zheng  proposed abandwidthallocation called new scheduling control that uses a tracker value to address the idle time problem under high trafﬁc loads. Although this algorithm improves the DBA2 idle time issue under heavy load conditions, it still wastes bandwidth under heavy load conditions because of the redundant overheads of the processing time of the tracker and the regular REPORT messages. Besides, it has an unfairness issue such that when the previous ONUs are operating under a light load, the following ONUs can share the remainder bandwidth, but the previous ONUs cannot allot the remainder bandwidth if the following ONUs are operating under a light load.
of motioncast by adjusting the speed of mobile nodes .
More sophisticated technique such as MR-MC is adopted at the aim of capacity improvements in .
So far, intuitively, there still remains an open question: what are the capacity and delay if wireless nodes in hybrid networks have the ability to move? The key feature of this question is the combination of infrastructure and mobility. It means unlike static cases, packets are able to be sent to basestations via mobility, which may lead to a smaller delay. On the other hand, with the help of basestations, two mobile nodes in MotionCast model are easier to communicate. Hence, although the situation is more complicated than considering only one of them, a better capacity and delay tradeoff is expected.
In this paper, bandwidthallocationfor search entities (i.e., movies) is base on abandwidthallocation weight (Ф), and then the server containing the search entity can choose a corresponding quality of movies for streaming service. Traditionally, if the bandwidthallocation of some search entity is over the server loading, the bandwidth sharing can only be performed among the search entities from the same requestor, called sibling-fair. However, cousin-fair is abandwidth sharing strategy that shares the over-allocated bandwidth of search entities from different requestors. Additionally, two improved methods, i.e., gated-service and re-provision, have been employed. By using the proposed bandwidth-based multi-quality streaming mechanism, both high bandwidth utilization and throughput maximization are achieved.
actual scene change anda single complex scene frame. However, any single complex scene frame wouldn’t interfere with the renegotiation process, which thus leads to the unavoidable loss. It is noted that the fast moving scenes with a single complex frame appear fora short time, which wouldn’t annoy human eyes. Instead, the scenes with little motion and simple frames are more sensitive to quality degradation. Therefore, the loss from a single complex frame is bearable compared with the benefit of longer allocation time. Table 1 shows the loss probability for all video traces as well. While major on-line interactive services such as video conferencing and distant learning are considered (see the traces Office and Lecture in Table 1), SBATP can obtain quite long allocation time (1299s, 577s) with very high utilization gain (94.76%, 91.32%) and nearly zero loss probability (below 10 -4 ). To further improve loss probability of playback services, the loss probability can be below 1% with β=2 for all traces but the utilization gain is relatively lower than β=1. Additionally, with extended control time for playback point, only single complex frame can lead
VI. C ONCLUSIONS AND F UTURE W ORK
Broadband networks and ubiquitous computing are driving development toward home networks built around some all-in-one digital home server. A trend is observed that regardless of how much bandwidth is available, new applications will be created to consume it. This paper has proposed a QoS-aware Residential Gateway (QRG) with real-time traffic monitoring anda QoS mechanism in order to initiate DiffServ-QoS bandwidth management during network congestion. Firstly, ORG classifies traffic flow to an appropriate class for optimized treatment for meeting user demands. Higher priority of traffic applications get the right to deliver first. Additionally, the QRG built-in traffic control function adopts CBQ for DiffServ-QoS bandwidth/traffic management to optimize utilization of bounded network bandwidth resources. CBQ provides fine granularity of bandwidth sharing and traffic priority control, including session level, enabling service level guarantees for individual flows and aggregate traffic. Network usage can be controlled and monitored even in large networks with thousands of users without severe performance degradation. Experimental implementations, not only in a general-purpose PC but also in a special-purpose modular low-power ARM920T embedded system, demonstrated the proposed QRG performs DiffServ-QoS well with CBQ bandwidth management mechanism on a Linux platform, thereby meeting the key goals of a cost-effective, low-maintenance, upgradeable, control and network gateway.
Chiapin Wang * , Wan-Jhen Yan and Hao-Kai Lo
The article presents a dynamic connection admission control (CAC) andbandwidth reservation (BR) scheme for IEEE 802.16e Broadband Wireless Access networks to simultaneously improve the utilization efficiency of network resources and guarantee QoS for admitted connections. The proposed CAC algorithm dynamically determines the admission criteria according to network loads and adopts an adaptive QoS strategy to improve the utilization efficiency of network resources. After new or handoff connections enter the networks based on current admission criteria, the proposed adaptive BR scheme adjusts the amount of reserved bandwidthfor handoffs according to the arrival distributions of new and handoff connections in order to increase the admission opportunities of new connections and provide handoff QoS as well. We conduct simulations to compare the performance of our proposed CAC algorithmand BR scheme with that of other approaches. The results illustrate that our approach can effectively improve the network efficiency in terms of granting more connections by as large as about 22% in comparison with other schemes, and can also guarantee adaptive QoS for admitted new and handoff connections.
However, it is still unclear how a carrier network shall organize its NFV datacenter resources into a coherent service architecture to support global network functional demands. This work proposes a hierarchical NFV/SDN-integrated architecture in which datacenters are organized into a multi-tree overlay network to collaboratively process user traffic flows. The proposed architecture steers traf- fic to a nearby datacenter to optimize user-per- ceived service response time. Our experimental results reveal that the 3-tier architecture is favored over others as it strikes a good balance between centralized processing and edge computing, and the resource allocation should be decided based on traffic’s source-destination attributes. Our results indicate that when most traffic flows within the same edge datacenter, the strategy whereby resources are concentrated at the carrier’s bot- tom-tier datacenters is preferred, but when most traffic flows across a carrier network or across different carrier networks, a uniform distribution over the datacenters or over the tiers, respective- ly, stands out from others.
Abstract—Packet scheduling in a WCDMA system poses a new challenge due to its nature of variable bit rates and location- dependent, time-varying channel conditions. In this work, three new downlink scheduling algorithms fora WCDMA base station are proposed to support multimedia transmissions. Using a credit management anda compensation mechanism, our algorithms provide rate guarantee and fair access to mobile terminals. In particular, we propose to allow a user to simultaneously use multiple OVSF codes in a time-sharing manner, which we call a multicode, shared model. Using multiple codes allows us to compensate those users suffering from bad communication quality or even errors. The proposed schemes can tolerate a multistate link condition (compared to the typically assumed two-state, or good-or-bad, link condition) by adjusting the number of OVSF codes and the spreading factor of each code. Simulation results show that the proposed schemes do achieve higher bandwidth utilization while keeping transmission delay low.
A system using optical two-level OFDM-ASK modulation is proposed and demonstrated. At the proposed RRH, the high data rate OFDM signal does not need to be signal processed, but is directly launched into a HSPD and subsequently emitted by an antenna. On the other hand, only a low bandwidth PD is needed to recover the low data rate ASK control signal. Hence, the proposed RRH is simple and provides low-latency. In order to maintain the signal performance of the control and payload signals, modulation ratio of the control signal is defined first. In our proof-of-concept experiment, wireless signal with 2.18 Gbit/s payload and 3.61 Mbit/s control signal is demonstrated and transmitted over 40 km SMF anda wireless channel with 256 ODN split-ratios. The proposed system can thus be operated over the ODN of the NG-PON2 systems. The deployment cost can thus be relieved.
Abstract—Downlink broadcast in LTE-Advanced andWiMAX-based relay networks is a crucial service for multimedia delivery. Currently most research effort goes into devising efficient resource allocation mechanisms to achieve more efficient resource utilization. However, spatial reuse, an important technique to improve transmission capacity, has received little attention in the literature. Thus, in this work, we investigate ways of achieving more efficient resource allocation in wireless relay networks via spatial reuse. We first formulate a joint spatial reuse and resource allocation problem as an integer linear programming (ILP) model. We then consider a grouping mechanism in which relay stations (RSs) are grouped together if they do not interfere with each other’s transmission signal. RSs in the same group can thus utilize spatial reuse by using the same set of resources to broadcast data. Because of the high computational complexity of ILP model, we propose a two-phase heuristic solution. In the first phase, the Enhanced-Resource Diminishing Principle approach is employed to determine the number of resources required by the base station anda set of selected RSs. In the second phase, a Max-Coloring algorithm is employed to organize the selected RSs into broadcast groups and then assign the required resources to each group by exploring the maximum advantage of spatial reuse. The simulation results show that the proposed solution improves system performance up to 61% as compared to two existing mechanisms.
The experiment consists of an off-line learning stage for NNCH anda real-time stage to test the performance of various handoff decision algorithms. In the off-line phase, the training data is collected at 22 different locations every 4m apart along the hallway. At each location, we collect 200 measurements of RSS, SNR, and PSR associated with AP1, AP2, and AP3 respectively while 40-byte UDP packets are transmitted once every 10 ms over the wireless link. In this experiment, we utilize (RSS, SNR) as the vector of RMI. Then neural networks are used to learn the mapping function from RMI to PSR. We use the feed-forward back-propagated networks with the topology of 6-12-3 nodes from input layer to the output. The nonlinear function in each node is sigmoid. The iteration is set as 100 with the learning rate of 0.02. We implement such the network by Matlab 6.0 Neural Network Toolbox. In the real-time phase, the locations indicated as “A”, “B”, “C”, and “D” in Figure 3 are sequentially passed. It totally spends 170 seconds at a walking speed about 0.5 meters per second. 680 measurements of RMI are made about every 0.125m apart along the route.
BLF. The performance of the hop-by-hop method and the floating rule are almost the same. The half rule performs
Unlike in a wired network, where the available bandwidth of a route is simply the minimum bandwidth of the links along the route, the calculation of the available bandwidth of a route in a mobile ad hoc network has been proved to be NP-complete. Based on the principle of genetic algorithms, in this paper, we have designed an efficient heuristic algorithm, which executed in a centralized manner, to solve the bandwidth calculation problem in the CDMA-over-TDMA channel model. Extensive computer simulations have been performed to compare the performance of our proposed GA method and that of other existing heuristic algorithms: the half rule, the floating rule, the hop-by-hop method, the bottleneck link firstalgorithm, and the tree algorithm. Simulation results verify that our GA can produce larger bandwidth than others.
Among others, access efficiency and power conservation are two critical performance indexes for assessing the effectiveness of wireless communication systems. In this paper, we present an ERB algorithm to reduce the response time of mobile clients' requests. We provide an analytical model to measure the expected access latency of the generated broadcast program. This analytical model helps formulate the optimum bandwidthallocationfor index and data channels. From the experimental results, it can be seen that our mechanism outperforms the existing data broadcast schemes in terms of access time. Moreover, the optimum bandwidthallocation also brings a signifi- cant improvement in energy conservation. Based on these advantages, it can be seen that the proposed mechanism is scalable and can feasibly increase the efficiency of data dissemination in broadcast-based systems.