Dynamic Cooperative MAC Protocol for Navigation Carrier Ad Hoc Networks: A DiffServ-Based Approach

Chao Gao, Bin Zeng, Jianhua Lu, Guorong Zhao
2017 Journal of Sensor and Actuator Networks  
In this paper, a dynamic cooperative MAC protocol (DDC-MAC) based on cluster network topology is proposed, which has the capability of differentiated service mechanisms and long-range communication. In DDC-MAC, heterogeneous communications are classified according to service types and quality of service (QoS) requirements, i.e., periodic communication mode (PC mode) is extracted with a QoS guarantee for high-frequency periodic information exchange based on adapt-TDMA mechanisms, while other
more » ... ices are classified as being in on-demand communication mode (OC mode), which includes channel contention and access mechanisms based on a multiple priority algorithm. OC mode is embedded into the adapt-TDMA process adaptively, and the two communication modes can work in parallel. Furthermore, adaptive array hybrid antenna systems and cooperative communication with optimal relay are presented, to exploit the opportunity for long-range transmission, while an adaptive channel back-off sequence is deduced, to mitigate packet collision and network congestion. Moreover, we developed an analytical framework to quantify the performance of the DDC-MAC protocol and conducted extensive simulation. Simulation results show that the proposed DDC-MAC protocol enhances network performance in diverse scenarios, and significantly improves network throughput and reduces average delay compared with other MAC protocols. of 22 whereby the cyclically occurring services are classified as a time-driven class, whereas stochastic services are classified as an event-driven class. Thereby, the medium access of the two classes is realized based on schedule-based MAC and contention-based MAC, respectively, or hybrid solutions including TDMA/CSMA, CDMA/CSMA, FDMA/CSMA, etc. In references [17, 18] , multiple services are classified based on QoS-aware criteria such as delay sensitivity and packet loss sensitivity. Saxena et al. [17] proposed a CSMA/CA approach, classifying the co-existing packets into two categories, i.e., streaming multimedia (over UDP) packets and Best Effort FTP (over TCP) packets. Moreover, Diff-MAC [18] is designed with the key features of service differentiation and QoS guarantee for heterogeneous traffic (e.g., video, voice and periodic scalar data), which is differentiated into three classes, i.e., real-time (RT) multimedia traffic, non-real-time (NRT) traffic and best effort (BE) traffic. Note that these DiffServ mechanisms are mainly proposed with one of or a hybrid of the following features: (i) adaptive contention window (CW) adjustment, (ii) dynamic duty cycling (changing active time), (iii) fragmentation and message passing for long packets, and (iv) intra-node and intra-queue prioritization [18] . However, these MAC protocols cannot fulfill the unique requirements of core-function-aware networks. Take NC-NET, for example; navigation service is the core function of NC-NET, which is essential to other multimedia services, even the services with stringent constraints on real-time variable bit rate, packet loss, and average delay. Thus, in this study, the design and analysis of the DiffServ mechanism, which can separate the kernel service from other functions, will be a basis for other technical details. Cooperative communication is another effective technique for realizing the advantages of spatial diversity, especially when NC-NET requires robust and real-time data communication, or the communication is impacted by high mobility, intermittent connectivity, and unreliability of the wireless medium. Thus, the theory behind it, depending on the application scenarios, can be classified into two categories: cooperative diversity, and packet relay by selected neighbor nodes. Cooperative diversity aims to offset the multi-path fading effect of wireless channels through multiple cooperative antennas, which can maximize the total network channel capacity [19] [20] [21] . For instance, CoopMAC [20] takes full advantage of the broadcast nature of the wireless channel, thus creating spatial diversity. Packet relay by selected neighbor nodes improves the link utilization probability by transmitting through the selected relay nodes, instead of transmitting directly to the destinations. In previous works, EC-MAC in reference [22] , and 2rcMAC in reference [23] are similar to our proposed protocol. EC-MAC adopts the best partnership selection algorithm to select the cooperative node with the properties of best channel conditions, highest transmission rate, and most balanced energy consumption. In 2rcMAC, the nodes update their relay table through a passive listening method, and obtain spatial diversity by a two-best-relay approach. However, this literature [20] [21] [22] [23] is mainly confined to the scenarios with features such as short transmission range, low dynamic or static nodes, and omni-directional antennas. The cooperative MAC for large-scale sparse network is still an open issue, and does not have full-rate network codes for directional transmission [24] [25] [26] . Both of them restrain the use of cooperative communication in a practical large-scale dynamic network. Furthermore, in the majority of works, only the relays that can decode the packet successfully during the first transmission can be activated and get involved in the possible ARQ retransmission; meanwhile, the other relays keep silent during the whole ARQ process. Nevertheless, they ignore the fact that the relays, which cannot decode the packet correctly during the first transmission, still have the chance to decode the packet correctly in the ARQ process.
doi:10.3390/jsan6030014 fatcat:zhyzoabtyfct3gc7lpqw5kfdg4