A spread slotted medium access control protocol with reservation supporting multimedia services over personal and mobile communication networks

In wireless communication networks the collision rates increase due to the fact that multiple users may transmit simultaneously. Medium Access Control (MAC) protocols are employed to lower the collision rates through organizing the access to the communication channels. The simplicity of future wireless networks such as Wireless Sensor Networks (WSNs) implies the need for rather simple MAC protocols, which would, in-turn require collision resolution between the packets simultaneously transmitted by multiple users. Slotted-ALOHA is a simple MAC protocol which has a limited throughput (36%) that is still very low to support future wireless applications. The goal of this paper is to gain deep understanding of how to improve the throughput and reduce the collision rate of slotted-ALOHA MAC protocol. In particular, we propose a novel Multi-Dimensional Slotted ALOHA (MDSA) protocol that combines the advantages of TDMA, FDMA and CDMA. MDSA protocol utilizes three dimensional reservation bands, i.e., time dimension, frequency dimension and code dimension. In this paper, we show theoretically how the successful reservation rates increase and the collision rates decrease with MDSA under idle and noisy channel conditions, which qualify our proposed scheme to be a reliable MAC protocol for wireless communication systems.

The key contributions of this paper are the proposed Pure Collective Aloha (PCA) medium access control (MAC) protocol with multilevel powers and its closed-form theoretical analysis. The PCA MAC protocol collects a batch of packets before transmitting these packets sequentially in the channel. The key idea in the design of this PCA MAC protocol with multilevel powers is to spread out the arrivals of each batch of packets in a channel and the multilevel powers of the packets received at the receiver allow capture for the case of the strongest signal power packet among the overlapping lower signal power packets to be successfully received at the receiver. If it is the only received packet, it is successfully received, regardless of its received power level. The PCA MAC protocol with multilevel powers is analyzed theoretically. The explicit closed-form expressions for the optimal offered loads and the maximum throughputs of the Pure Aloha, the Slotted Aloha and the PCA MAC protocols with multilevel powers are presented. The numerical results show that the throughput of the asynchronous PCA MAC protocol with multilevel powers is about 90.5% better than that of the asynchronous Pure Aloha MAC protocol with multilevel powers and can approach the maximum throughput bound of the synchronous Slotted Aloha MAC protocol with multilevel powers, without the need of any synchronization mechanism to slot boundaries.

An ubiquitous network for multimedia personal communications (Personal Communications Network (PCN)) with small, individual low-cost terminals is one of the most ambitious worldwide projects for the 21st century that are being pursued nowadays. In the development of such PCN, Geostationary, Medium, and Low Earth Orbiting (GEO, MEO, LEO) satellite constellations will play a fundamental role to provide worldwide coverage for most services required by the end-user. The characteristics of efficiency and flexibility inherently required by that scenario suggest, amidst other possibilities, to take into special consideration a radio interface based on code division multiple access (CDMA) to ensure, in addition to the features mentioned above, a sufficient grade of power and spectral efficiency of the relevant satellite radio link. The aim of this paper is a review of the current status of those issues in the field of satellite CDMA transmission systems design that, in our opinion, appear fundamental to the successful operation of an efficient PCN. In particular, we survey the techniques for multiplexing, coding and transmission of direct-sequence spread spectrum (DS/SS) signals, and we touch upon the techniques for the minimization of the self-noise effect, and the related topics of power-control and multiuser detection. We also shortly address in this respect some technological aspects related to an efficient modem design via digital signal processing techniques. The final part of the paper deals more specifically with some typical issues of satellite transmission, namely the minimization of the detrimental effects of the nonlinear satellite transponder and of multipath propagation; the applicability of diversity reception to a multisatellite network is also addressed as possible means of performance boost.

Multi-carrier code division multiple access (MC-CDMA), a novel, high capacity, multicarrier modulation scheme, is developing to a key radio transmission technology for future wireless local area networks (W-LANs). However in ad hoc code division multiple access (CDMA) networks near-far effects can block a receiver due to high interference. These effects occur when a receiving station is closer to an interferer than to its corresponding transmitter. Accordingly, the receiver cannot detect the intended signal out of the received one and the data transmission fails. In this work, we present an adaptive medium access control (MAC) protocol for ad hoc MC-CDMA based W-LANs, based on the IEEE 802.11 MAC protocol. The new protocol has the ability to overcome the near-far-problem by employing a frequency adaptation method. The key of the proposed method is an interference estimate built at each receiving mobile station (MS). Aided by its estimate, a MS can calculate whether the quality of service (QoS) expectations of the incoming link can be accomplished. If the interference is too high, the receiving MS initiates a frequency channel change and informs the corresponding transmitter over the control packets about the Id of the new channel. It is shown that this concept can deploy the high capacity characteristics of MC-CDMA in wireless environments

Since cognitive wireless network (CRN) has the characteristic of secondary use, it can enable the device to dynamically access available spectrum without interference to primary users (PUs), which can effectively alleviate contradiction between the lack of spectrum resources and the growing demand for wireless access. However, Medium Access Control (MAC) protocol as CRN core components, can achieve competition access of the licensed spectrum and coordination control, which will maximize spectrum utilization efficiency and network throughput. The contribution of this survey is threefold. First, we analyze the characteristics of the existed multi- channel MAC protocol in CRN; Second, according to the different ways of spectrum access in CRNs, the multi-channel MAC protocols are classified into time-slotted based MAC protocol, control channel based MAC protocol and hybrid MAC protocol, and the paper emphatically analyzed the advantages and disadvantages of these multi-channel MAC protocols; Finally, the paper explores the difficulties and the challenges of multi-channel MAC protocols design in cognitive wireless network.

Various ongoing research efforts in Vehicular Ad hoc Network (VANET) related to safety and non-safety applications have been published in academia and industry. One of the main areas in VANET that is still lacking of significant research contributions is toward designing reliable Medium Access Control (MAC) protocols. Existing surveys on MAC protocols in VANET mostly discuss general MAC methods, that include contention-based and contention-free MAC protocols. A hybrid MAC protocol that adopts both contention-based and contention-free MAC, proposed to enhance the network performance in VANET, is fruitful to be explored further. Hence, a survey of hybrid MAC protocols for VANET is presented in this paper. The benefits and limitations of the existing hybrid MAC protocols are discussed based on their classification to provide some insights into the recent advancement of high-performance MAC protocols for vehicular networks. Finally, some open research issues are highlighted as part of future research directions that need further investigations.

Primarily used in military communications in the past, code division multiple access (CDMA) has become attractive for personal communications. As a large number of mobile hosts are supported and a wide range of services are provided, one important issues in a CDMA personal communication network is the control of the uplink access to the wireless spectrum. In this paper, we address it in a realistic situation where the receiver-oriented transmission protocol is employed and multiple access interference (MAI) cannot be ignored. A medium access control protocol for voice and data integration is proposed. It solves the problems of code assignment and MAI control at the same time. A Markov chain model is used to analyze the protocol. Based on the modeling, the effectiveness of the protocol's MAI control is demonstrated and some system design issues are investigated.

In the Vehicular ad hoc networks, safety applications are capable of sending and processing messages in real time is the most notable difference between safety and non-safety application. This message is also known as packet where information is transmitted at regular interval. To tell the neighbors about the vehicle profile the packet are generated and broadcasted consecutively. The information about the vehicle such as speed, acceleration, coordination, and the next coordination, etc. is contained in packets. The Vehicular ad hoc networks are vigorously changing the packet needs to be sent regularly. Because of safety-related issues, this is needed which can only be solved by the real-time information. However, due to increasing the packet and some environmental factors, if the channel becomes overloaded, there will be an increase in the packet collision probability and communication get a breakdown by destroying packet or information. Hence, the probability of successfully received the packets and the environmental condition is an important parameter for a Vehicular ad hoc networks based system. Because the Vehicular ad-hoc network propagation is strongly affected due to varying nature of the environment. The radio propagation path loss models use mean additional attenuation sophisticated fading model and do not consider the obstacle caused due to obstacles of vehicles in Line of Sight of transmitting and receiving vehicles/devices. This affects the attenuation signal at receiving vehicles. Therefore, we present an obstacle based radio propagation model that considers the effect caused by the presence of obstructing vehicles in Line of Sight. The experiment is conducted to evaluate the model under different environmental conditions (City, Highway, and Rural) by varying vehicle density to study the effect of throughput operation and packet collision considering environmental factor for multi-channel DSRC based Vehicle-to-Vehicle communication in IEEE 802.11p considering distributed slotted Medium Access Control protocol. The performance of the model was evaluated in terms of throughput, collision, and packet delivery ratio. City environment achieves a 15.04% average packet delivery ratio performance improvement over the other two environment considering varied vehicles. The overall result shows that the proposed obstacle based throughput model is efficient considering varied density.

Distributed queuing collision avoidance (DQCA) is a hybrid medium access control (MAC) protocol that can inherently accommodate large node densities; however it may not be capable of handling the order of magnitude of devices in Machine-to-Machine (M2M) networks, which is an order higher than the existing WLANs. To address this issue, we propose a hybrid MAC protocol that uses orthogonal codes for channel contention, coupled with a power based priority assignment scheme for scheduling the data transmissions. The simulation results show that the proposed protocol is well suited for M2M networks and outperforms DQCA.

In this paper, we design a Medium Access Control (MAC) protocol for Wireless Body Area Network (WBAN) to allocate slot to packets of each medical and non-medical node. Although a hybrid MAC protocol is defined in IEEE 802.15.6 as the international standard of WBAN, the detail specification depends on the implementation. It is important to consider the Quality of Service (QoS) requirements of each node and packet in WBAN, because different sensor nodes generate time varying packets which generate depending on human behavior. Besides, permissible delay time of each medical and non-medical node is different. To improve both priority control for QoS and dependability, we propose a MAC protocol with slot prediction algorithm. Simulation results show that our protocol outperforms IEEE 802.15.6 in terms of transmission success rate and worst delay time.

International audience

An application of decentralized location registration (DLR) information storage method has been investigated for multimedia services through mobile communication networks. Various kinds of multimedia services will be introduced in mobile communication networks in quite near future. Since a service area of such mobile communication system can be nationwide or even worldwide, information delivery cost to each mobile unit will be increased because the distances between a central storage office and each unit is large and there may be too many units communicating at the same time. To minimize the cost and increase the network efficiency, it is possible to apply the DLR-information storage method, which the author has proposed for personal communication networks, to this field. The author demonstrates an easier authentication method by adopting a decentralized mobile control center which memorizes the communication history of each personal communication unit.

Vehicular ad hoc network (VANET) is an emerging and promising technology, which allows vehicles while moving on the road to communicate and share resources. These resources are aimed at improving traffic safety and providing comfort to drivers and passengers. The resources use applications that have to meet high reliability and delay constraints. However, to implement these applications, VANET relies on medium access control (MAC) protocol. Many approaches have been proposed in the literature using time division multiple access (TDMA) scheme to enhance the efficiency of MAC protocol. Nevertheless, this technique has encountered some challenges including access and merging collisions due to inefficient time slot allocation strategy and hidden terminal problem. Despite several attempts to study this class of protocol, issues such as channel access and time slot scheduling strategy have not been given much attention. In this paper, we have relatively examined the most prominent TDMA MAC protocols which were proposed in the literature from 2010 to 2018. These protocols were classified based on scheduling strategy and the technique adopted. Also, we have comparatively analyzed them based on different parameters and performance metrics used. Finally, some open issues are presented for future deployment.

Multipath propagation in a broadband CDMA environment is described. A propagation model for broadband spread-spectrum signals is presented. Experimental results relating to the sharing of the band by fixed service microwave users and mobile personal communications network (PCN) users are discussed. Field tests indicate that PCN systems can provide high-quality communications when sharing the spectrum with fixed-service microwave systems in suburban and urban areas.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

최근 HFC(Hybrid Fiber Coax) CATV 망이 초고속망의 하부구조로 자리를 잡아가고 있다. HFC-CATV 망의 상향채널은 가입자에서 헤드엔드로 데이터 전송시 500가입자 이상이 공유하기 때문에 충돌이 발생하게 된다. 특히, 음성, 비디오 그리고 데이터와 같은 다양한 종류의 트래픽 QoS(Qualify of Service)를 만족시키기 위해서 서비스별로 우선순위를 고려한 알고리즘이 요구되어진다. IEEE 802.14에서 제안된 우선순위 기반 3진 트리(Ternary tree)알고리즘은 정적 PNA(Priority New Access) 슬롯 구조를 가진다. 이 방법은 실시간으로 변화하는 트래픽의 요구 지연(request delay)이 높게 유지되며 서로 다른 우선순위 트래픽의 요구 경쟁 확률이 동일하다는 문제점을 가지고 있다. 따라서, 본 논문에서는 동적 PNA(Priority New Access) 슬롯 구조를 제안하여 높은 우선순위 트래픽의 요구지연을 낮게 하고 새로운 스테이션에 대해 우선순위 별로 경쟁 확률을 다르게 하는 알고리즘을 제안한다. 동일한 조건하에 두 알고리즘에 대해 요구지연 값을 비교 분석하였다. 성능 분석 결과 동적 PNA 우선순위 충돌해결알고리즘이 정적 PNA 우선순위 충돌해결알고리즘보다 낮은 요구지연을 가진다는 것을 확인할 수 있었다. Recently, the HFC-CATV network stand in a substructure of superhighway information network. Because of sharing up to 500 of subscribes, the Collision Resolution Algorithm needs in the upstream channel of HFC-CATV network. In order to provide Quality of Service (QoS) to users with real-time data such as voice, video and interactive service, the research of Collision Resolution Algorithm must include an effective priority scheme. In IEEE 802.14, the Collision Resolution Algorithm has high request delay because of static PNA(Priority New Access) slots structure and different priority traffics with the same probability. In order to resolve this problem, this paper proposed dynamic priority collision resolution algorithm with ternary tree algorithm. It has low request delay according to an increase of traffic load because high priority traffic first resolve and new traffic content with different probability. In the result of the simulation, it demonstrated that the proposed algorithm needs lower request delay than that of ternary tree algorithm with static PNA slots structure.