An Adaptive Topology Optimization Strategy for GNSS Inter-satellite Network

Inter satellite link (ISL) is an effective way for the global navigation satellite system (GNSS) to reduce its dependence on ground infrastructure, which guarantees constellation orbit determination and satellite communication. When the number of onboard Ka-band ISL antennas is less than that of visible satellites, the inter-satellite link assignment of GNSS causes a problem. For the problem of inter-satellite link scheduling, considering that the result of the allocated link has a feedback effect on the subsequent link assignment as a priori knowledge, an adaptive topology optimization algorithm based on signed variance (ABSV) is proposed. In order to meet the requirements of communication and ranging performance, the time slot is divided into a communication time slot and a ranging time slot. Taking the waiting delay time of satellite communication and PDOP as measurement indexes, the proposed strategy is simulated for 10080 min. The results show that the ranging performance of this strategy is better than other recently published methods, which verifies the effectiveness of signed variance for adaptive link planning and is also beneficial to the survivability of constellation.

An Adaptive Topology Optimization Strategy for GNSS Inter-satellite Network

Inter satellite link (ISL) is an effective way for the global navigation satellite system (GNSS) to reduce its dependence on ground infrastructure, which guarantees constellation orbit determination and satellite communication. When the number of onboard Ka-band ISL antennas is less than that of visible satellites, the inter-satellite link assignment of GNSS causes a problem. For the problem of inter-satellite link scheduling, considering that the result of the allocated link has a feedback effect on the subsequent link assignment as a priori knowledge, an adaptive topology optimization algorithm based on signed variance (ABSV) is proposed. In order to meet the requirements of communication and ranging performance, the time slot is divided into a communication time slot and a ranging time slot. Taking the waiting delay time of satellite communication and PDOP as measurement indexes, the proposed strategy is simulated for 10080 min. The results show that the ranging performance of this strategy is better than other recently published methods, which verifies the effectiveness of signed variance for adaptive link planning and is also beneficial to the survivability of constellation.

Self-organizing topology for energy-efficient ad-hoc communication networks of mobile devices

When physical communication network infrastructures fail, infrastructure-less communication networks such as mobile ad-hoc networks (MANET), can provide an alternative. This, however, requires MANETs to be adaptable to dynamic contexts characterized by the changing density and mobility of devices and availability of energy sources. To address this challenge, this paper proposes a decentralized context-adaptive topology control protocol. The protocol consists of three algorithms and uses preferential attachment based on the energy availability of devices to form a loop-free scale-free adaptive topology for an ad-hoc communication network. The proposed protocol has a number of advantages. First, it is adaptive to the environment, hence applicable in scenarios where the number of participating mobile devices and their availability of energy resources is always changing. Second, it is energy-efficient through changes in the topology. This means it can be flexibly be combined with different routing protocols. Third, the protocol requires no changes on the hardware level. This means it can be implemented on all current phones, without any recalls or investments in hardware changes. The evaluation of the protocol in a simulated environment confirms the feasibility of creating and maintaining a self-adaptive ad-hoc communication network, consisting of multitudes of mobile devices for reliable communication in a dynamic context.