Wireless communication is used in many different situations such as mobile telephony, radio and TV broadcasting, satellite communication, wireless LANs, and military operations. In each of these situations a frequency assignment problem arises with application specific characteristics. Researchers have developed different modeling ideas for each of the features of the problem, such as the handling of interference among radio signals, the availability of frequencies, and the optimization criterion.

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Models and solution techniques for frequency assignment problems

In the deployment of wireless mesh networks (WMNs) the placement of Mesh Nodes (MNs) is an important design issue. The performance of WMNs is greatly affected by the location of the MNs. As it is difficult to place the MNs in a regular pattern in the real deployment, finding the optimal locations in the deployment environment is of much interest for the service providers. For a given possible locations for the MNs and the user density in the deployment environment, we aim to find the locations of the MNs to be used that maximizes the coverage and the connectivity of the network together. Due to high computational complexity of the exhaustive searching algorithm, an efficient local searching algorithm is proposed. Numerical results show that, the local search algorithm can give close to optimal performance with much lower time complexity than exhaustive searching.

Node Placement Algorithm for Deployment of Two-Tier Wireless Mesh Networks

Efficient channel assignment is crucial for successful deployment and operation of IEEE 802.11-based WLANs. In this article we present a survey on the state of the art channel assignment schemes in IEEE 802.11-based WLANs. After detailing out all the schemes, we provide a qualitative comparison among different schemes in terms of algorithm execution behaviors, complexity, and scalability. We then conclude the survey with several research issues open for further investigation.

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Channel assignment schemes for infrastructure-based 802.11 WLANs: A survey

IEEE 802.11 wireless LAN : Capacity analysis and protocol enhancement

In this article, network deployment and resource management issues are revisited in the context of green radio communication networks with sustainable energy supply. It is argued that under the green network paradigm powered by renewable energy, the fundamental design criterion and main performance metric have shifted from energy efficiency to energy sustainability. As an effort to this end, in this article, new network solutions are proposed with an objective of improving network sustainability; the proposed solutions ensure that dynamically harvested energy can sustain the traffic demands in the network. Specifically, the placement issue of green access points (i.e., APs powered by sustainable energy sources) is investigated to meet the energy and QoS demands of mobile users; and an adaptive resource management scheme is proposed to address the unreliability of renewable energy in QoS provisioning. It is shown that by mitigating the energy depletion probability of green APs, sustainable network performance can be significantly improved.

Dimensioning network deployment and resource management in green mesh networks

To deploy a multi-cell 802.11 wireless local area network (WLAN), access point (AP) placement and channel assignment are two primary design issues. For a given pattern of traffic demands, we aim at maximizing not only the overall system throughput, but also the fairness in resource sharing among mobile terminals. A novel method for estimating the system throughput of multi-cell WLAN is proposed. An important feature of this method is that co-channel overlapping is allowed. Unlike conventional approaches that decouple AP placement and channel assignment into two phases, we propose to jointly solve the two problems for better performance. The optimal solution can be found using exhaustive searching. Due to the high computational complexity involved in exhaustive searching, an efficient local searching algorithm, called patching algorithm, is designed. Numerical results show that for a typical indoor environment, patching algorithm can provide a close-to-optimal performance with much lower time complexity than exhaustive searching

/pdf/joint-access-point-placement-and-channel-assignment-for-802-100t671v6k.pdf

Joint access point placement and channel assignment for 802.11 wireless LANs

To deploy a multi-cell IEEE 802.11 wireless local area network (WLAN), access point (AP) placement and channel assignment are two primary design issues. For a given pattern of traffic demands, we aim at maximizing not only the overall system throughput, but also the fairness in resource sharing among mobile terminals. A novel method for estimating the system throughput of a multi-cell WLAN is proposed. An important feature of this method is that cochannel overlapping is allowed. Unlike conventional approaches that decouple AP placement and channel assignment into two phases, we propose to solve the two problems jointly for better performance. Due to the high computational complexity involved in exhaustive searching, an efficient local searching algorithm, called patching algorithm, is also designed. Numerical results show that for a typical indoor environment, the patching algorithm can provide a close-to-optimal performance with much lower time complexity.

/pdf/joint-access-point-placement-and-channel-assignment-for-802-3pycepr1eg.pdf

Millimeter‐wave techniques have been developed significantly due to their benefits of higher data rate compared with the lower band and more extensive coverage compared to the higher frequency. However, because of the equipment of a large‐scale antenna array, further low‐complexity channel estimation and precoding algorithms in the hybrid beamforming structured wireless system must be researched for real‐world implementation. This study serves that aim, particularly on multi‐beam training, with the output of this work can be regarded as baseband equivalent channel estimation. First, we present a novel ternary‐tree‐based fully‐activated hierarchical codebook based on the sub‐array division technique. The proposed hierarchical codebook surpasses its conventional binary‐tree‐based counterpart designed by using antenna deactivation in charge of the training overhead and synthesis performance of the hierarchical search. Following that, inspired by multi‐beam linear search, we develop two hierarchical linear search methods according to our proposed hierarchical codebook. Finally, simulation results show that they outperform linear search schemes regarding training complexity and the effective achievable rate.

Hierarchical multi‐beam training with the presence of the sub‐connected hybrid beamforming architecture

Due to the open nature of wireless communication, malicious electromagnetic jamming has long been a severe threat to the establishment and stability of communication links. To address this anti-jamming problem, a Markov decision process (MDP) with a two-dimensional action space consisting of transmit frequency and power is proposed in this paper, modeling the interaction between a normal communication link and the presence of malicious jammers in a frequency hopping (FH) communication system. Furthermore, we also prove the existence of the deterministic optimal policy of the proposed model theoretically. To obtain a policy for the communication link to avoid being jammed, the Dual Action Network-Based Deep Reinforcement Learning Algorithm, and Action Feedback Mechanism are proposed. The energy consumption and frequency switching overhead are considered and evaluated in both the proposed model and the algorithm. Finally, the proposed model and algorithm are verified not only in a virtual simulation environment but also in the field testing environment. The result suggests that the proposed algorithm is of great practical value for solving anti-jamming problems.

Xiang Ling

Papers

Joint access point placement and channel assignment for 802.11 wireless LANs

Joint access point placement and channel assignment for 802.11 wireless LANs

Hierarchical multi‐beam training with the presence of the sub‐connected hybrid beamforming architecture

Deep Reinforcement Learning-Based Anti-Jamming Algorithm Using Dual Action Network