Mobile networks have seen more than a thousand times traffic increases in the past decade. Network operators face an ever increasing demand and cost to deploy denser networks in order to maintain the quality of services. In view of this paradigm shift, an open cloud radio access network (C-RAN) service model is studied in this work. Integrating the cross-layer functions of spectrum resource sharing, channel and power allocation, and interference management in a C-RAN architecture, we explore the feasibility of providing a scalable yet efficient broadband wireless service with dense small cell networks (DSN). The proposed methods and architecture can be applied to DSN that support the functions of (further enhanced) inter-cell interference cancelation (feICIC/ICIC) techniques of 3GPP standard, and have the potential to provide a cost-effective solution for high-quality DSN. Simulation results across an area of 100 km$^{2}$show that the proposed scheme can offer an aggregate downlink throughput of 21 Gbps over a maximum channel bandwidth of 20 MHz, which is 5 times the throughput with a typical ICIC method. Moreover, the service satisfaction degree can reach 85% under the proposed C-RAN architecture, making it a promising and cost-effective solution for future broadband wireless services.

The throughput performance of smart antenna systems (SASs) in WiFi networks is studied in this work. Considering a WiFi network whose access points (APs) support the switched-beam SAS, a beam switching strategy which is compatible with the legacy WiFi protocol is proposed to enhance more concurrent links by allowing APs directionally sensing and accessing the wireless channel. The throughput advantage is verified by the simulation results in random deployment scenarios. More importantly, the proposed beam switching strategy provides extra design factors to adjust or balance the downlink and uplink throughput per WiFi user to meet the requirements of various applications and scenarios.

This paper studies the deployment problem of Bluetooth Low Energy (BLE) gateways, and proposes an effective algorithm for it to support e-Healthcare services in hospitals or daycare centers. With the acceleration of aging, demands for elder care services have increased dramatically. Gateway deployments for Internet of Things (IoT) play an important role to support such services over remote intelligent healthcare platforms, in particular when allowing patients wearing wireless medical devices to walk freely in wards or indoor spaces. The gateway deployment problem becomes much more complicated under this condition due to obstacles and human bodies in the way between the gateways and the patients. In addition, the hardware specification of a gateway and the signal shadowing by patients themselves also limit the connectivity capacity of a gateway. These motivate us to study a design that takes all the factors of indoor floor plan, radio propagation attenuation, user densities, and human body signal shadowing into the consideration of gateway deployment. Particular features of our proposed algorithm include: 1) guaranteeing a full signal coverage; 2) accounting for patients' self-shadowing effects; and 3) adapting to non-uniform user densities in different spaces of indoor environments. The average user service continuity degree can reach up to 0.99 in indoors with various sizes of room spaces and user densities. Moreover, performances of the average gateway serving load implies the selected locations to deploy gateways are adequate.

The throughput performance of a heterogeneous dense small cell network (HetNet) with collocated WiFi and LTE interfaces is studied herein. From a geometrical statistical viewpoint, the average throughput for LTE with the function of further enhanced inter-cell interference coordination (FeICIC) is investigated in an attempt to find a proper operation setting for FeICIC to benefit users on cell edges. Furthermore, the optimal setting for WiFi offloading is also studied to maximize the worse user experience in such a HetNet. The proposed analysis method allows us to further study a proper strategy that provides fair services to users under the severe interferences in HetNet.

A practical and effective service deployment method is proposed for coordinated multi-point (CoMP) transmissions in ultra-dense networks (UDN). Despite the potential of UDN for throughput enhancement, the throughput of edge users is still considerably deteriorated by interferences from adjacent cells. Applying the CoMP transmissions among cells appears to be a feasible solution to resolve this issue. However, the nature of the almost randomly deployed locations of small cell base stations (BSs) and their limited numbers of antennas make it difficult to design an effective resource coordination mechanism for the CoMP services in UDN. Reconsidering this problem from an antenna allocation viewpoint, we present a simple yet effective approach to improve the cell-edge throughput under a centralized radio access network architecture. The first step is to partition the entire service area into multiple subareas, and the second step is to allocate the antenna degrees of freedom to each subarea. To improve the scalability of this service method, a two-tier service deployment method is further introduced based on the BS clustering and service area partitioning of the entire network. The simulation results show that the proposed service architecture can provide a significant improvement on the cell-edge throughput while still maintaining a good average throughput in the UDN.

A joint beam training and rate adaptation mechanism for downlink transmissions is presented for multiple input multiple output systems with switched beam antennas. The proposed method only depends on the beam patterns and the acknowledgement (ACK) replied by the receiver, and is compatible with the legacy WiFi standards. This feature makes not only the complexity of the beam training scheme extremely low, but also the feasibility relatively high. Due to the practical limitations of antenna designs and manufacturing, beam patterns may not have distinctive directivity for certain directions. Therefore, beam pattern scaling is utilized to make the resultant beam patterns match well with the ideal user directions and channel conditions.Simulation results with real switched beam patterns show that the precision of the training scheme is very high.

Coordinated multipoint (CoMP) transmission has been considered an important technology to manage the serious inter-cell interference in ultra-dense small cell networks (UDN). In this paper, a scheduling framework and a two-tier spectrum resource allocation method for CoMP transmissions in UDNs are proposed. For a number of clusters, the tier-one allocation divides the resource blocks (RBs) into two sets: one is for center users and the other is for edge users. Tier-two resource allocation is performed at a central scheduler to allocate spectrum resources to edge users on a cluster basis. Applying the two-tier scheduling method to a simulated UDN on OpenStack and OpenAirInterface (OAI) software platforms, the UE throughput performances are presented and discussed. We further analyze the computational complexity of each step for performing 1-slot CoMP transmission. The numerical simulation results showed that, upon deploying the small cells in a Poisson Point Process (PPP) with mean density 0.0003/km2, and the ratio of eNBs to UEs is (3:1), more than 50% UEs have 15Mbps throughput performance.

Despite that network capacity can increase with cell densification, interferences from adjacent cells may deteriorate the throughput of users close to cell edges. To alleviate this problem and to offer a service quality with no significant cell edge degradation, we propose a feasible coordinated multi-point (CoMP) transmission architecture from a new look on antenna allocation in dense small cell networks (DSN). The CoMP idea is based on a two-step mechanism; the first step partitions the entire service region into multiple areas, and the second step adjusts the number of active users for each area. We then develop an antenna allocation algorithm to enhance the cell-edge user throughput, making use of the spatial multiplexing (SM) gain, array gain and cooperative diversity gain. Simulation results show that applying SM to DSN plays a crucial role to enhance the user throughput. And one of our proposed cooperative schemes is shown to have a great potential to improve the throughput for a large portion of users or the cell service area.

The exponential growth of wireless data traffic has pushed wireless network vendors and researchers to rethink of a revolutionizing architecture for the fifth generation (5G) wireless network that is capable of supporting 100 times the network capacity of the current 3G/4G systems, yet is able to reduce the net energy consumption of the systems by up to 90 percent. Numerous concepts and technologies have been proposed to approach this goal from various aspects of system design. A consensus reached so far is that 5G is going to be a collection of technology evolutions that include soft core networks, small or even no cellular, pervasive but invisible base stations, and heterogeneous yet self-organizing radio access networks. In addition to advanced radio access technologies, the success of such an ambitious goal really relies on a flexible and scalable network infrastructure to accommodate and harmonize these technologies. On the other hand, virtualization is viewed as one of the essential technologies of the 5G network to provide cost effectiveness of management, maintenance, and hardware upgrade. In this paper, we introduce a cloud service model that has the potential to serve the numerous stringent requirements for future 5G networks. Besides, we describe the designed auto scaling and load balancing rules of each functional block defined in the cloud service model. We conduct emulation to evaluate the performance of resource utilization for the cloud data center.

The exponential growth of wireless data traffic has pushed wireless network vendors and researchers to seek for new paradigms to revolutionize the traditional communication technologies to support 100 times the network capacity of the current communication systems. Therefore, cognitive radio (CR) has been one of the most promising technologies for the next generation communication system, such as 802.11af and the ongoing efforts to define CR for LTE-A and beyond systems. In view of this development trend, in this paper, we propose a control channel design for heterogeneous CR networks (CRNs) that also incorporate the WiFi air interface. Based on the proposed control channel, an analytical model is further developed to analyze the throughput for a certain kind of these heterogeneous CRNs. Both the analytical and simulation results are presented and discussed.

A cooperative spectrum sharing, power allocation and user scheduling method is studied in this work under the framework of LTE self-organizing femtocell networks. Making use of dynamic channel and power allocation, and interference control, all femto access points (APs) in a self-organizing network (SON) can share the channels available to the SON with guaranteed quality of service. Simulation results show that the effective channel usage ratio can reach 75% in average even with no explicit cellular planning inside the service area of an SON. This result supports the feasibility of randomly deploying large numbers of femto APs in metropolitan areas based on the concept of SON.

Due to the power consumption issue of user equipment (UE), Single-Carrier FDMA (SC-FDMA) has been selected as the uplink multiple access scheme of 3GPP Long Term Evolution (LTE). Similar to OFDMA downlink, SC-FDMA enables multiple UEs to be served simultaneously in uplink as well. However, the single carrier characteristic requires that all the allocated subcarriers to a UE must be contiguous in frequency with each time slot. Moreover, a UE should adopt the same modulation and coding scheme at all allocated subcarriers. These two constraints do limit the scheduling flexibility. In this paper, we formulate the UL scheduling problem with proportional fairness support by taking two constraints into consideration. Since this optimization had been proven to be an NP-hard problem, we further develop one heuristic algorithm. We demonstrate that competitive performance can be achieved in terms of system throughput, which is evaluated by using 3GPP LTE system model simulations.

Due to the facts of wireless data usage being increasing faster now than ever before and more multimedia content being generated by users and uploaded to the network, multi-user MIMO (MU-MIMO) technology would be crucial to improve the LTE-A uplink spectral efficiency for meeting the service demands. On the other side, adopting clustered SC-FDMA technology as the uplink multiple access scheme of LTE-A means that a User Equipment (UE) can be allocated more than one cluster which consists of contiguous RBs (this is the contiguity constraint). Moreover, all allocated RBs to a UE must use the same modulation and coding scheme (this is the robust rate constraint). The two constraints make MU-MIMO UL scheduling more complicated. In this paper, we formulate the MU-MIMO UL scheduling problem with taking two constraints into consideration. Since this optimization had been proven to be an NP-hard problem, we further develop two low-complexity heuristic algorithms. We demonstrate that competitive performance can be achieved in terms of system throughput and fairness index.

Due to the power consumption issue of user equipment (UE), Single-Carrier FDMA (SC-FDMA) has been selected as the uplink multiple access scheme of 3GPP Long Term Evolution (LTE). Similar to OFDMA downlink, SCFDMA enables multiple UEs to be served simultaneously in uplink as well. However, the single carrier characteristic requires that all the allocated subcarriers to a UE must be contiguous in frequency with each time slot. Moreover, a UE should adopt the same modulation and coding scheme at all allocated subcarriers. These two constraints do limit the scheduling flexibility. In this paper, we formulate the UL scheduling problem with taking two constraints into consideration. Since this optimization had been proven to be an NP-hard problem, we further develop a heuristic algorithm with low complexity. We demonstrate that competitive performance can be achieved in terms of system throughput, which is evaluated by using 3GPP LTE system model simulations.

LONG-TERM EVOLUTION (LTE) is expected to ensure 3GPP's competitive edge over other cellular technologies. The advantages of LTE include improving end-user throughputs, and reducing latency. LTE systems utilize a network-controlled and the user equipment (UE) assisted handover procedure for mobility in connected mode. In this paper, we first introduce the measurement report mechanism defined in the specification of LTE systems. We further explore possible problems and the impact on handover decision. Followed, we propose rules for timer adjustment, including timeToTrigger and reportInterval. Our mechanism aims at reducing incorrect handover decisions and maximizing the throughput performance. By conducting simulation, we evaluate the designed mechanism. The simulation results show that our proposed mechanism does achieve our design goals.

Beamforming technique is used in IEEE 802.15.3c networks to avoid high propagation attenuation and path loss, and improve the overall system throughput by exploiting spatial channel reuse. In this paper, we introduce the necessity and design challenges of inter-piconet communications. Based on our observation, we propose a joint design of relay selection and scheduling. For relay selection, we define “interference-free”, “concurrence-restricted extent”, and “concurrence index” for properly selecting relays to improve the degree of spatial channel reuse. The designed scheduling consists of two phases: intra-piconet flow scheduling and inter-piconet flow scheduling. After performing phase 1 operations, intra-piconet flows are scheduled and the total required channel time is known. The phase 2 operations are to use the least channel time extension to schedule all inter-piconet flows. We evaluate our algorithm through simulations. The results show that the joint algorithm performs well and does achieve its objectives.

Long Term Evolution (LTE) is a promising technology for 4G mobile networks. Due to utilize OFDMA in downlink and SC-FDMA in uplink, the LTE system is expected to provide significantly high throughput with 20 MHz spectrum allocation. To increase the cell throughput and multi-user diversity gain, channel dependent scheduling (CDS) is implemented for the OFDMA-based multi-user scenario to allocate resource blocks (RBs) to users experiencing better channel conditions. Nevertheless, CDS may not perform well in SC-FDMA due to its two inherent constraints one is contiguous RB assignment and the other is robust modulation and coding mode. In this paper, the formulation of resource allocation for a SC-FDMA system upon considering two inherent constraints is proposed. Since the optimization problem of resource allocation in SC-FDMA is NP-hard, we further propose two heuristic algorithms to find feasible solutions. We evaluate the proposed formulation and heuristic algorithms by conducting simulation. The simulation results show that our methods achieve significant performance improvement not only in system sum throughput but also in transmission delay.

In this paper, we introduce the concept of "route robustness" for path selection in multi-hop cognitive radio networks. We demonstrate that the aggregate throughput and the robustness of routes determined by the proposed route selection strategy are superior to existing rate-based selection strategies. The rationale behind our approach is to guarantee a basic level of robustness for a set of routes (referred to as skeletons in this paper). Then, we select some routes from this robust route set and determine the spectrum to be allocated on each link along these routes such that the system throughput is maximized. We also design a polynomial time algorithm for this problem, and evaluate our proposed mechanism via simulations. The results show that our proposed algorithm indeed achieves a near optimal solution of this problem for multi-hop overlay CR networks.

IEEE 802.15.3c has recently been formed for developing a millimeter-wave (mmWave)-based wireless personal area networks (WPANs). It utilizes 60 GHz license-free spectrum and provides very high data rate (over 3 Gbps). To deal with the problems of high propagation attenuation and path loss, beamforming antennas are utilized. In this paper, we consider the characteristics of beamforming to design an efficient scheduling algorithm. Specifically, we integrate axis alignment and location determination into scheduling mechanism. The designed scheduling algorithm improves the degree of spatial and directional channel reusability and the overall system performance. We evaluate our approach through simulations. The simulation results show that the designed scheduling algorithm performs well and does achieve its objectives.

The IEEE 802.16 standard is a promising technology for 4G mobile networks. Though supporting versatile service classes, best effort (BE) service class is expected to dominate WiMAX networks, due to operational simplicity. One of bandwidth request mechanisms that subscriber stations (SS) can utilize to issue bandwidth requests (BW-REQ) for BE connections is contention-based random access. An SS starts a timer T16 when transmitting a BW-REQ. If getting a grant before timer expiration, the SS transmits data packets at the allocated time slots; otherwise it performs truncated binary exponential backoff process for BW-REQ retransmission. The default value of T16 is one frame time. However, T16 impacts on contention and request collision significantly. In the paper, we develop an analytical model for T16 timer setting. Besides, we derive analytical expressions for the average number of tries per BW-REQ and the average packet delay. We compare the theoretical results of fixed and adjustable timers. The results show that adjusting timer reduces both the number of collision and the average packet delay.

Vehicular ad hoc network (VANET) is a special class of mobile ad hoc Networks (MANET), and is an important component of Intelligent Transportation System (ITS). VANET has a future potential in terms of a rich set of applications that it can provide to its customer. Accident detection is a key functionality of ITS. Due to the effects of channel fading and shadowing, individual vehicles may not be able to reliably detect the existence of an accident. In this paper, we propose a linear cooperation framework for accident detection in a cluster-based VANET. In this framework, accident detection is based on the linear combination of local statistics gathered by individual vehicles. Our objectives are minimizing the probability of false alarm and avoiding broadcast storm. Based on the problem formulation and derivation, we proposed two efficient algorithms to do alarm detection: local detection and global detection. The numerical results show that our heuristic strategies perform well on false alarm detection.

One of the most challenging issues in cognitive radio systems is channel sensing and channel accessing. In this paper, a synchronized channel-sensing and accessing for cognitive radio users in IEEE 802.11 wireless networks is proposed. The mechanism consists of two phases: fast channel sensing and proactive channel vacating. Fast channel sensing is for a pair of cognitive radio users to search an available channel time-efficiently; proactive channel vacating is for the pair of cognitive radio users to be aware of the presence of primary users and vacate the occupied channel as quick as possible. We utilize the concept of channel hopping to reduce the average channel sensing time of cognitive radio users. Besides, through the designed interruption mechanism, cognitive radio users can create opportunities for primary users to claim the spectrum and thus minimize the caused interference to primary users. From the simulation results, our proposed protocol can efficiently balance the tradeoff between throughput performance of a cognitive radio network and waiting time of primary users to claim channels.

Network coding has attracted much attention in recent years due to the capability of transmission reduction and throughput improvement. In this paper, a redundancy-based delivery mechanism is proposed. This delivery mechanism utilizes network coding and linear combination on original packets to regenerate packets, which are called coded packets. Upon receiving a minimum number of coded packets, the destination can decode and get all original packets. Through theoretical analysis on delivery rate and overhead, we further propose an utility function to determine a proper redundancy degree and observe the suitable range of packet error rates to implement our delivery mechanism. Furthermore, the proposed delivery mechanism is applied to link adaptation. The simulation results show that by utilizing our proposed delivery, the operating SNR range of each PHY mode is lowered. In other words, when channel condition gets worse, one mobile device can still operate in the same PHY mode by utilizing the proposed delivery mechanism.

In this paper, we study the determination of downlink (DL) and uplink (UL) channel split ratio for Time Division Duplex (TDD)-based IEEE 802.16 (WiMAX) wireless networks. In a TDD system, uplink and downlink transmissions share the same frequency at different time intervals. The TDD framing in WiMAX is adaptive in the sense that the downlink to uplink bandwidth ratio may vary with time. In this work, we focus on TCP based traffic and explore the impact of improper bandwidth allocation to DL and UL channels on the performance of TCP. We then propose an adaptive split ratio (ASR) scheme which adjusts the bandwidth ratio of DL to UL adaptively according to the current traffic profile, wireless interference, and transport layer parameters, so as to maximize the aggregate throughput of TCP based traffic. Our scheme can also cooperate with the base station (BS) scheduler to throttle the TCP source when acknowledgements (ACKs) are transmitted infrequently. The performance of the proposed ASR scheme is validated via ns-2simulations. The results show that our scheme outperforms static allocation (such as the default value specified in the WiMAX standard and other possible settings in existing access networks) in terms of higher aggregate throughput and better adaptivity to network dynamics.

The IEEE 802.11(p)/1609 standard is an emerging technology for vehicular communication networks. It amends the IEEE 802.11-2007 standard and defines a new WAVE operational mode for vehicular environments. The WAVE mode utilizes a combined FDMA/TDMA scheme to manage network bandwidth. In this mode, a node must periodically switch its frequency channel between two different channels over time. Such a design may result in bandwidth wastage due to the residual time caused by channel switching. In this paper, we propose two easy-to-implement schemes to mitigate this problem and compare their TCP/UDP performances with those of the original scheme. Our simulation results provide many insights into the operations of these schemes on IEEE 802.11(p)/1609 networks and show that the proposed schemes always outperform the original scheme.

The advancement of mobile computing is mainly limited by battery lifetime of a end device, and thus power management is always a critical design issue in various wireless networks. To conserve power consumption of mobile subscribe stations (MSSs), three types of power saving classes are defined in the IEEE 802.16e standard. However, the defined power saving mechanism is per-connection basis, and thus when an MSS has multiple connections, the power saving efficiency degrades significantly. In this paper, a Least-Awake-Frames Scheduling (LAFS) algorithm is proposed to achieve both energy saving and Quality-of-Service (QoS) fulfillment. The proposed LAFS consists of three phases to take all service classes into consideration. The goals of the first two phases are determining awake-frame candidate sets for unsolicited grant service (UGS) connections and sleep/awake intervals for connections of the remaining service classes; the third phase is to determine sleep and awake frames of an MSS. The simulation results show that our proposed LAFS algorithm outperforms the power saving protocol defined in the IEEE 802.16e, and other existing power saving algorithms.

Wireless channel qualities vary and degrade due to fading and interference. Cooperative communication has characteristics of spatial diversity and virtual antenna, and thus it can improve communication efficiency significantly. One of the essential design issues in cooperative communication is partner selection mechanism. In this paper, we propose a partner selection algorithm which utilizes two decision factors: channel quality and unavailability. In this paper, channel quality is represented as signal-to-noise ratio, and unavailability of a node is the time duration it cannot act as a partner for its neighbors. When operating in cooperative mode, a source designates one neighbor, which satisfies the channel quality requirement and has the least unavailability value, as its partner. Furthermore, how to integrate the proposed partner selection mechanism with the IEEE 802.11 medium access control (MAC) protocol is elaborated. We evaluate our proposed algorithm by conducting simulations. From the simulation results, our proposed partner selection algorithm improves system throughput, reduces frame delivery time, and increases spatial channel reuse degree.

The advancement of mobile computing is mainly limited by battery lifetime of an end device, and thus power management is always a critical design issue in various wireless networks. To conserve power consumption of mobile subscribe stations (MSSs), three types of power saving classes are defined in the IEEE 802.16e standard. However, the defined power saving mechanism is per-connection basis. When having multiple connections, the power saving efficiency of an MSS degrades significantly. In this paper, a Least-awake-frames scheduling (LAFS) algorithm is proposed to achieve both energy saving and quality-of-service (QoS) fulfillment. The proposed LAFS consists of three phases. The goals of the first two phases are determining awake-frame candidate sets of unsolicited grant service (UGS) connections and sleep/awake intervals of remaining service-classes connections; the third phase is to determine sleep and awake frames of an MSS. The simulation results show that our proposed LAFS algorithm outperforms the power saving protocol defined in the IEEE 802.16e, and other existing power saving algorithms.

IEEE 802.16 Broadband Wireless Access system (BWA) is a promising emerging technology. In the IEEE 802.16 standard, multiple data transmission rates are defined by employing different modulation and channel coding schemes. How to select a proper mode affects the system performance significantly. In this paper, an efficient link rate adaptation algorithm, named QoS-aware Link Rate Adaptation (Q-LRA), is proposed. Q-LRA takes both QoS demand and channel condition into consideration to determine the best mode. The QoS demand of a connection is represented as packet error rate (PER). Based on the specified PER, the BS calculates the required signal-to-noise ratio (SNR) threshold of each mode. By comparing the measured SNR and all modes' SNR thresholds, the BS suggests the SS the best mode. The performance of Q-LRA is evaluated by simulations. The simulation results show that Q-LRA improves system throughput and guarantees each connection's QoS demand.

We study fair scheduling in ad hoc networks, accounting for channel errors. Since wireless channels are susceptible to failures, to ensure fairness, it may be necessary to compensate those flows on error-prone channels. Existing compensation mechanisms need the support of base stations and only work for one-hop wireless channels. Therefore, they are not suitable for multihop wireless networks. Existing fair scheduling protocols for ad hoc networks can be classified into timestamp-based and credit-based approaches. None of them takes channel errors into account. We investigate the compensation issue of fair scheduling and propose a mechanism called Timestamp-Based Compensation Protocol (TBCP) for mobile ad hoc networks. We evaluate the performance of TBCP by simulation and analyze its long-term throughput. The results show that our analytical result provides accurate performance estimation for TBCP.

We study fair scheduling with quality of service (QoS) support for wireless ad hoc networks. Two types of flows are considered: best effort and guaranteed flows. The goal is to satisfy the minimum bandwidth requirements of guaranteed flows and to provide a fair share of residual bandwidth to all flows. We compare timestamp-based and credit-based mechanisms, and evaluate the feasibility of all existing fair scheduling schemes of these two types of mechanisms for multimedia wireless multihop networks. We suggest a flow weight calculation scheme for existing timestamp-based mechanisms to support both best effort and guaranteed flows, and propose a credit-based mechanism called credit-based slot allocation protocol (CSAP) for fair scheduling with QoS support. For comparison purposes, several metrics are defined to evaluate the performances of these two kinds of mechanisms. The simulation results show that CSAP outperforms the other approaches in terms of meeting the minimum requirements of guaranteed flows, fairly sharing the residual bandwidth among all flows, and improving overall system throughput.

This paper studies resource management for multimedia mobile ad hoc networks (MANET). In particular, we focus on providing fair scheduling with quality-of-service (QoS) support for MANET. We consider two types of flows: guaranteed and best effort flows. The goal is to satisfy the QoS requirements of guaranteed flows and to provide global fairness for best effort flows. In this paper, a credit-based fair scheduling mechanism called credit-based slot allocation protocol (CSAP) is proposed. In CSAP, nodes are logically grouped into clusters, each with a scheduler. Each scheduler assigns time slots to nodes in its cluster based on the first tier algorithm. The node scheduled to send at the next time slot then in turn assigns the time slot to a relayed flow determined by the second-tier algorithm. Each multihop flow is treated as multiple single-hop flow segments. These segments are then correlated such that a downstream segment will not be allocated a slot unless the upstream segments have all been allocated. We evaluate the performance of CSAP by simulations. The results show that CSAP meets the QoS requirements of guaranteed flows, provides global fairness for best effort flows, and improves overall system throughput.

The paper studies fair scheduling with quality of service (QoS) support in ad hoc networks. The goal is to satisfy the minimum bandwidth requirements of guaranteed flows and to provide a fair share of residual bandwidth among all flows. We propose a new cluster-based mechanism called two-tier slot allocation protocol (2TSAP), which improves system throughput and ensures per-cluster fairness while satisfying the requirements of guaranteed flows. With 2TSAP, the network is logically partitioned into clusters, each with a scheduler. The scheduler assigns time slots to mobiles in the affiliated clusters based on the first tier algorithm. The mobiles scheduled to send at the next time slot then in turn assign the time slot to flows determined by the second tier algorithm. We compare the performance of 2TSAP with Q EMLM-FQ, a virtual-time based fair scheduling mechanism with QoS support. The simulation results show that 2TSAP meets the minimum requirements of guaranteed flows, shares the residual bandwidth fairly among all flows, and improves overall system throughput.