Conflict Graph Based Concurrent Transmission Scheduling Algorithms for the Next Generation WLAN
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Conflict Graph Based Concurrent Transmission Scheduling Algorithms for the Next Generation WLAN Zhongjiang Yan1
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Two conflict graph based concurrent transmission scheduling algorithms are proposed in this paper to efficiently solve the spatial TDMA (STDMA) scheduling problem for the next generation WLAN. Firstly, the STDMA scheduling problem for multiple timeslots is formulated as an multiple-step optimization problem. Secondly, a bi-weighted conflict graph is constructed to model the concurrent transmissions’ interference relationships, where the nodes denote the transmission request and the weights of the edges denote the interference level between any two transmission request nodes. If the interference between two transmission nodes is larger than the given interference threshold, then there are no edge between these two nodes. And only the acceptable interferences are modelled as the edges. Finally, a heuristic clique based algorithm (HCBA) and an optimal clique based algorithm (OCBA) are proposed, where HCBA assigns the transmission requests to the multiple timeslots one by one while OCBA assigns the transmission requests to the multiple timeslot once. The performance gap between the optimal one and the suboptimal one is evaluated. Simulation results show that HCBA not only has low complexity but also achieves similar performance comparing to OCBA. Keywords Conflict graph · Concurrent transmission · Next generation wlan
1 Introduction As the density of the wireless local area (WLAN) network increases [1], the data transmission requirements of the users increase [2]. How to accommodate these large transmission requirements becomes a significant challenge to further improve the network throughput. Therefore, the standard organization of IEEE starts the standardization work for IEEE 802.11ax [3], 11ay [4] and 11be [5]. Among these standard, orthogonal frequency divisional multiplexing access (OFDMA) [6], multi user multiple input multiple output (MU-MIMO) and directional beamforming are key technologies to pursue high network throughput. To efficiently schedule multiple concurrently
This work was supported by the National Natural Science Foundations of China (No. 61771392). Zhongjiang Yan
[email protected] 1
School of Electronics and Information, Northwestern Polytechnical University, Xi’an 710072, China
transmission links is significant to pursue the high network throughput. Existing works of [7–17] have investigated the concurrent transmission problem. Most of them solve the spatial TDMA (STDMA) scheduling problem in a timeslot to timeslot scheme. In other words, in most of the existing works the 1st timeslot is always to be assigned the concurrent transmission requests first, and then the 2nd, the 3rd and the later timeslots are assigned consequently one after another. Although the problem to assign one of the multiple timeslots is difficult, i.e., an NP-complete problem, exhaustive search scheme can be used to solve the opti
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