Flexible Subcarrier Allocation for Interleaved Frequency Division Multiple Access
Flexible Subcarrier Allocation for Interleaved Frequency Division Multiple Access
复制标题
交织频分多址的灵活子载波分配
DOI：
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发表时间：
2020
影响因子：
10.4
通讯作者：
S. Liew
中科院分区：
文献类型：
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作者：
Yulin Shao;S. Liew
交织频分多址（IFDMA）和正交FDMA（OFDMA）属于一类信号调制和多址技术，其中多个用户的信息被复用并承载在共享频谱内的子载波上。与OFDMA相比，IFDMA具有更低的峰均功率比（PAPR）。然而，IFDMA对子载波分配提出了两个严格的约束：1）用户占用的子载波必须在可用子载波之间均匀间隔。2)用户使用的副载波的数量必须是副载波总数的除数。除非能够克服这些约束，否则IFDMA尽管具有出色的PAPR，但仍可能不切实际。本文研究如何克服这些限制，允许灵活和细粒度的子载波分配IFDMA。具体而言，我们提出了$i$）比特反转子载波分配方案，其中分配均匀间隔的子载波的问题被转换为填充连续的bin的更直观的问题; $ii$）多流IFDMA方案，其中用户可以具有任意数量的子载波。对于同步的情况下，用户的请求以同步的方式到达，我们表明，IFDMA可以实现相同的水平的灵活性和粒度OFDMA的子载波分配。对于异步的情况下，用户请求到达和离开异步，我们表明，IFDMA的阻塞概率只是略差于OFDMA的：具体地说，差距之间的阻塞概率IFDMA和OFDMA是只有2.56%，在一个温和的提供的负载。
Interleaved Frequency Division Multiple Access (IFDMA) and Orthogonal FDMA (OFDMA) belong to a class of signal modulation and multiple-access techniques in which information of multiple users are multiplexed and carried on subcarriers within a shared spectrum. Compared with OFDMA, IFDMA has lower Peak-to-Average Power Ratio (PAPR). However, IFDMA poses two rigid constraints on subcarrier allocation: 1) the subcarriers occupied by a user must be evenly-spaced among the available subcarriers. 2) the number of subcarriers used by a user must be a divisor of the total number of subcarriers. Unless these constraints can be overcome, IFDMA may remain impractical despite its excellent PAPR. This paper investigates how to overcome these constraints to allow flexible and fine-grained subcarrier allocation in IFDMA. Specifically, we put forth $i$ ) a bit-reversal subcarrier allocation scheme whereby the problem of allocating evenly-spaced subcarriers is transformed to a more intuitive problem of filling contiguous bins; $ii$ ) a multi-stream IFDMA scheme whereby a user can have an arbitrary number of subcarriers. For the synchronous scenario in which user requests arrive in a synchronous manner, we show that IFDMA can achieve the same level of flexibility and granularity as OFDMA in subcarrier allocation. For the asynchronous scenario in which user requests arrive and depart asynchronously, we show that the blocking probability of IFDMA is only slightly worse than that of OFDMA: specifically, the gap between the blocking probabilities of IFDMA and OFDMA is only 2.56% at a moderate offered load.