بهینه‌سازی تخصیص توأم پیوند کاربر، تخصیص زیرکانال و تخصیص توان در شبکه‌های OFDMA ناهمگون

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده فنی و مهندسی برق دانشگاه شاهد، تهران، ایران

2 دانشگاه شاهد

3 گروه مخابرات دانشکده فنی مهندسی دانشگاه شاهد

چکیده

این مقاله مسئله پیوند کاربر، تخصیص زیرکانال و تخصیص توان به‌صورت توأم را در کانال فراسوی یک شبکه مخابراتی ناهمگون با بهره­مندی از راهکار تسهیم فرکانسی متعامد (OFDMA) و با فرض محدود بودن حداکثر توان ارسالی هر کاربر مورد بررسی قرار می­دهد. نشان داده می­شود که مسئله پیش رو یک مسئله غیر خطی ترکیبی پیوسته گسسته غیر محدب است. در این راستا جهت قابل حل نمودن آن، شرط گسسته بودن متغیرهای مسئله رهاسازی شده و در عوض یک عبارت هزینه به تابع هدف اضافه می­شود تا گسسته بودن این متغیرها در جواب نهایی تضمین شود. درنهایت برای حل مسئله، تابع هدف به‌صورت تفاضل دو تابع محدب (D.C) بازنویسی شده و سپس با استفاده از روش تقریبی سلسله مراتبی محدب، مسئله ساده­سازی ­شده حل می­شود. شایان ذکر است تا آنجایی که نویسندگان مطلع می­باشند، مسئله تخصیص زیرکانال، پیوند کاربر و کنترل توان تاکنون به‌صورت توأم در کانال فراسوی شبکه­ها­ی مخابراتی ناهمگون مورد بررسی قرار نگرفته است. با مقایسه نتایج شبیه­سازی ملاحظه می­شود که راهکار پیشنهادی نسبت به راهکارهای ارائه ‌شده موجود با تحمل پیچیدگی محاسباتی بالاتر، نرخ بهتری را حاصل می­کند.

کلیدواژه‌ها


عنوان مقاله [English]

Joint Optimization of User Association, Subchannel Allocation and Power Allocation in OFDMA Heterogeneous Networks

نویسندگان [English]

  • S. M. Hashemi 1
  • S. Akhlaghi 2
  • M. Forouzanmehr 3
1 Department of Electrical Engineering, Shahed University, Tehran, Iran
2 shahed university
3 Electrical Engineering Department, Shahed University
چکیده [English]

This paper investigates joint user association, sub-channel assignment, and power allocation in the    uplink of multi-user orthogonal frequency division multiple access (OFDMA) of a heterogeneous network (HetNet) where users are subject to maximum transmission power constraints. It is shown that the           underlying problem is a highly non-convex mixed integer non-linear problem. To tackle the problem, the integer variables are relaxed and a penalty function is added to the objective function to make sure that the relaxed variables take binary values. Finally, the objective function is rewritten as the difference of two convex (D.C.) functions and the resulting problem is addressed through using the successive convex       approximation method. It is worth mentioning that, to the best of the author’s knowledge, the problem of joint user association, sub-channel allocation, and power control in the uplink of a heterogeneous network has not been addressed in the literature till now. Simulation results demonstrate the superiority of the     proposed method over existing works in terms of achieving higher throughput despite exhibiting a higher complexity.
 

کلیدواژه‌ها [English]

  • User-Association
  • Subchannel and Power Allocation
  • Heterogeneous Networks (HetNets)
  • Uplink Network
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