IEEE 802.11be是 IEEE 802.11 標準的下一個修訂版，目的是藉由增強IEEE 802.11 實體層(PHY)和媒體存取控制(MAC)在大量站台(STA)傳輸中實現超高吞吐量(EHT)和低延遲表現。IEEE 802.11be利用上行正交分頻多重接取(OFDMA)隨機存取(UORA)來提供大量未調度的站台同時傳輸數據包的機會。考慮到UORA一旦有大量站台同時競爭資源會造成巨量衝突發生，有許多針對UORA性能作改良的提案。其中分群是一種常見來改善隨機存取效能的方向，然而目前對於分群UORA的研究僅限於片面或針對特殊情景並沒有現成的分析模型可以用來調查不同配置下分群UORA的行為。本篇論文考慮到這些問題後提出兩種分群UORA系統的分析模型。第一種是一般分群，傳輸考量一群傳完後再換下一群；另一種是穿插分群，允許每個群與其他群穿插並依序執行其UORA，目的是為了減少分群時越後面輪到的群的訪問延遲。我們主要藉由所提模型在不同限制條件下根據給定的總資源數和站台數來最大化存取成功機率，這些調查結果也同時展現所提模型的重要性和實用性。

IEEE 802.11be is the next amendment of the 802.11 IEEE standard that aims to enhance the IEEE 802.11 physical layer (PHY) and medium access control (MAC) for the transmission of massive stations (STAs) with extremely high throughput (EHT) and low delays. Uplink orthogonal frequency division multiple access (OFDMA) random access (UORA) is utilized in IEEE 802.11be to solicit the chance of massive unscheduled STAs transmitting their packets simultaneously. Considering UORA would suffer several collisions once massive STAs compete for resources, there are many proposals for improving the performance of UORA. Among these, grouping is one common direction. However, the current research on grouping-based UORA is limited to one-sided or special-case studies and there isn't a ready-made analytical model that could be used to investigate the different configurations of grouping-based UORA behavior. This paper takes these issues into account and then develops 2 different grouping-based UORA systems. One is the general grouping that only assigns the next group until the STAs in the previous group finish their transmission, and the other is an interleaving grouping that allows every group to be interspersed with other groups and execute their UORA which aims to decrease the access delay from the later groups. For a given number of STAs and the reserved RUs, we mainly utilize the proposed analytical models to find the best grouping configuration which maximizes the access success probability under the given constraint. The investigations show the importance and practicality of the proposed models.

[1] “IEEE P802.11ax/D3.3 Draft standard for information technology –Telecommunications and information exchange between systems –Local and metropolitan area networks –Specific requirements –Part 11: Wireless LAN medium access control (MAC) and physical layer (PHY) specifications – Amendment 1: Enhancements for high efficiency WLAN,” tech. rep., Dec. 2018.
[2] “IEEE P802.11be/D2.1 Draft standard for information technology –Telecommunications and information exchange between systems –Local and metropolitan area networks –Specific requirements –Part 11: Wireless LAN medium access control(MAC) and physical layer (PHY) specifications – Amendment 8: Enhancements for extremely high throughput (EHT),” tech. rep., Jul. 2022.
[3] “Wi-Fi Alliance 2018 Wi-Fi Predictions.” https://www.wi-fi.org/news-events/newsroom/ wi-fi-alliance-publishes2018-wi-fi-predictions.
[4] C. Deng, X. Fang, X. Han, X. Wang, L. Yan, R. He, Y. Long, and Y. Guo, “Ieee 802.11be wi-fi 7: New challenges and opportunities,” IEEE Communications Surveys Tutorials, vol. 22, no. 4, pp. 2136– 2166, 2020.
[5] D. Lopez-Perez, A. Garcia-Rodriguez, L. Galati-Giordano, M. Kasslin, and K. Doppler, “Ieee 802.11be extremely high throughput: The next generation of wi-fi technology beyond 802.11ax,” IEEE Communications Magazine, vol. 57, no. 9, pp. 113–119, 2019.
[6] G. Naik, S. Bhattarai, and J.-M. Park, “Performance analysis of uplink multi-user ofdma in ieee 802.11ax,” in 2018 IEEE International Conference on Communications (ICC), pp. 1–6, 2018.
[7] E. Khorov, I. Levitsky, and I. F. Akyildiz, “Current status and directions of ieee 802.11be, the future wi-fi 7,” IEEE Access, vol. 8, pp. 88664–88688, 2020
[8] S. Brahmi, M. Yazid, and M. Omar, “Multiuser access via ofdma technology in high density ieee 802.11ax wlans: A survey,” in 2020 Second International Conference on Embedded Distributed Systems (EDiS), pp. 105–110, 2020.
[9] L. Lanante, C. Ghosh, and S. Roy, “Hybrid ofdma random access with resource unit sensing for nextgen 802.11ax wlans,” IEEE Transactions on Mobile Computing, vol. 20, no. 12, pp. 3338–3350, 2021.
[10] D. G. Filoso, R. Kubo, K. Hara, S. Tamaki, K. Minami, and K. Tsuji, “Proportional-based resource allocation control with qos adaptation for ieee 802.11ax,” in ICC 2020 - 2020 IEEE International Conference on Communications (ICC), pp. 1–6, 2020.
[11] M. Kuran, A. Dilmac, O. Topal, B. Yamansavascilar, S. Avallone, and T. Tugcu, “Throughputmaximizing ofdma scheduler for ieee 802.11ax networks,” in 2020 IEEE 31st Annual International Symposium on Personal, Indoor and Mobile Radio Communications, pp. 1–7, 2020.
[12] M. Wu, J. Wang, Y.-H. Zhu, and J. Hong, “High throughput resource unit assignment scheme for ofdma-based wlan,” in 2019 IEEE Wireless Communications and Networking Conference (WCNC), pp. 1–8, 2019.
[13] B. Binoy and B. S. Vineeth, “Minimum delay scheduling under average power constraint for 802.11ax uplink,” in 2019 IEEE International Conference on Advanced Networks and Telecommunications Systems (ANTS), pp. 1–5, 2019.
[14] K. Wang and K. Psounis, “Scheduling and resource allocation in 802.11ax,” in IEEE INFOCOM 2018 - IEEE Conference on Computer Communications, pp. 279–287, 2018.
[15] E. Avdotin, D. Bankov, E. Khorov, and A. Lyakhov, “Enabling massive real-time applications in ieee 802.11be networks,” in 2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), pp. 1–6, 2019.
[16] A. Behara and T. G. Venkatesh, “Fluid-limit model for dynamic mu-ofdma resource allocation of wi-fi6 networks,” IEEE Communications Letters, vol. 26, no. 1, pp. 207–211, 2022.
[17] W.-J. Lee, W. Shin, J. A. Ruiz-de Azua, L. F. Capon, H. Park, and J.-H. Kim, “Noma-based uplink ofdma collision reduction in 802.11ax networks,” in 2021 International Conference on Information and Communication Technology Convergence (ICTC), pp. 212–214, 2021.
[18] S. Brahmi and M. Yazid, “Towards a hybrid access to resource units in multi-user ofdma communications,” in International Conference on Artificial Intelligence in Renewable Energetic Systems, pp. 421–429, Springer, 2021.
[19] W. Wydmański and S. Szott, “Contention window optimization in ieee 802.11ax networks with deep reinforcement learning,” in 2021 IEEE Wireless Communications and Networking Conference (WCNC), pp. 1–6, 2021.
[20] K. Kosek-Szott and K. Domino, “An efficient backoff procedure for ieee 802.11ax uplink ofdma-based random access,” IEEE Access, vol. 10, pp. 8855–8863, 2022.
[21] N. Shahin, R. Ali, S. W. Kim, and Y.-T. Kim, “Adaptively scaled back-off (asb) mechanism for enhanced performance of csma/ca in ieee 802.11ax high efficiency wlan,” in NOMS 2018 - 2018 IEEE/ IFIP Network Operations and Management Symposium, pp. 1–5, 2018.
[22] R. Ali, N. Shahin, R. Bajracharya, B.-S. Kim, and S. W. Kim, “A self-scrutinized backoff mechanism for ieee 802.11 ax in 5g unlicensed networks,” Sustainability, vol. 10, no. 4, p. 1201, 2018.
[23] E. Avdotin, D. Bankov, E. Khorov, and A. Lyakhov, “Ofdma resource allocation for real-time applications in ieee 802.11ax networks,” in 2019 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom), pp. 1–3, 2019.
[24] J. Bai, H. Fang, J. Suh, O. Aboul-Magd, E. Au, and X. Wang, “Adaptive uplink ofdma random access grouping scheme for ultra-dense networks in ieee 802.11ax,” in 2018 IEEE/CIC International Conference on Communications in China (ICCC), pp. 34–39, 2018.
[25] J. Bai, H. Fang, J. Suh, O. Aboul-Magd, E. Au, and X. Wang, “An adaptive grouping scheme in ultradense ieee 802.11ax network using buffer state report based two-stage mechanism,” China Communications, vol. 16, no. 9, pp. 31–44, 2019.
[26] A. Yang, B. Li, M. Yang, and Z. Yan, “Spatial clustering group-based ofdma multiple access protocol with carrier sensing for the next-generation wlans,” in 2018 IEEE International Conference on Signal Processing, Communications and Computing (ICSPCC), pp. 1–6, 2018.
[27] J. Jung and J. Lim, “Group contention-based ofdma mac protocol for multiple access interference-free in wlan systems,” IEEE Transactions on Wireless Communications, vol. 11, no. 2, pp. 648–658, 2012
[28] Y. Annan, B. Li, Y. Mao, Y. Zhongjiang, and Y. Xie, “Utility optimization of grouping-based uplink ofdma random access for the next generation wlans,” Wireless Networks, vol. 27, no. 1, pp. 809–823, 2021.
[29] M. Peng, B. Li, Z. Yan, and M. Yang, “A spatial group-based multi-user full-duplex ofdma mac protocol for the next-generation wlan,” Sensors, vol. 20, no. 14, p. 3826, 2020.
[30] C.-H. Wei, P.-C. Lin, and R.-G. Cheng, “Comment on ‘an efficient random access scheme for ofdma systems with implicit message transmission’,” IEEE Transactions on Wireless Communications, vol. 12, no. 1, pp. 414–415, 2013.
[31] Y.-J. Choi, S. Park, and S. Bahk, “Multichannel random access in ofdma wireless networks,” IEEE Journal on Selected Areas in Communications, vol. 24, no. 3, pp. 603–613, 2006.
[32] C.-H. Wei, G. Bianchi, and R.-G. Cheng, “Modeling and analysis of random access channels with bursty arrivals in ofdma wireless networks,” IEEE Transactions on Wireless Communications, vol. 14, no. 4, pp. 1940–1953, 2015.
[33] C.-H. Wei, R.-G. Cheng, and S.-L. Tsao, “Modeling and estimation of one-shot random access for finite-user multichannel slotted aloha systems,” IEEE Communications Letters, vol. 16, no. 8, pp. 1196–1199, 2012.
[34] R.-G. Cheng, C.-M. Yang, B. S. Firmansyah, and R. Harwahyu, “Uplink ofdma-based random access mechanism with bursty arrivals for ieee 802.11ax systems,” IEEE Networking Letters, vol. 4, no. 1, pp. 34–38, 2022.
[35] F. Wilhelmi, S. Barrachina-Muñoz, and B. Bellalta, “On the performance of the spatial reuse operation in ieee 802.11ax wlans,” in 2019 IEEE Conference on Standards for Communications and Networking (CSCN), pp. 1–6, 2019.