This paper proposes a novel multi-step broadcast control (MBC) scheme to deploy a group of autonomous mobile agents for accomplishing coverage tasks in a bounded region. Traditional broadcast control (BC) schemes use a one-to-all communication framework to transmit a uniform signal to all agents, making it cost-effective compared with any all-to-all communication-based scheme for a multi-agent system. However, as BC schemes are based on a single-step view of the environment for decision-making, the environment’s varying distribution density is not known immediately to the agents, resulting in suboptimal performance. To overcome this drawback, this paper proposes an MBC scheme, where agents use a predictive multi-step view and are able to detect the varying densities in the environment ahead of time. The local controller output is estimated using a weighted averaging technique which assigns a higher weight to immediate steps; this feature compensates for any decrease in prediction accuracy as the number of steps increases. We demonstrate the effectiveness of the proposed MBC scheme using a coverage task over a region with uneven population density. Compared to existing BC schemes, the proposed MBC scheme shows superior convergence characteristics in task accomplishment and deployment efficiency.
Past studies have established that in the S-band range of 2GHz, rain attenuation is negligible. However, every year, heavier rain intensities are being experienced in tropical countries like Malaysia due to current global warming conditions. The study presented in this paper aims to quantify the rain attenuation that is suffered by Worldwide Interoperability for Microwave Access (WiMAX) signals in the 2.3GHz in medium city and suburban environments in some parts of Malaysia. The Received Signal Strengths gathered in field experiments were used to calculate the rain attenuation in dB/km in various rain rates. The results show that in suburban environment, the rain attenuation was calculated to be 0.22dB/km at a rain rate of 65.4mm/hr. In medium city environment, the rain attenuation was calculated to be between 0.1958dB/km and 0.2676dB/km for rain rates between 70.2mm/hr to 74.7mm/hr. Wet foliage tends to increase Radio Frequency signal absorption. Therefore, the study findings may be significant in the planning of WiMAX and Long Term Evolution link-budgets, especially if wide-range coverage is envisioned in rural areas.
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