# Cross-Cycled Uplink Resource Allocation over NB-IoT  
[PERSON]  
1 Department of Computer Science and Information Engineering, National University of Kaohsiung, Kaohsiung 811, Taiwan; [EMAIL_ADDRESS] (Y.-J.Y.); [EMAIL_ADDRESS] (Y.-H.H.)  
[PERSON]  
1 Department of Computer Science and Information Engineering, National University of Kaohsiung, Kaohsiung 811, Taiwan; [EMAIL_ADDRESS] (Y.-J.Y.); [EMAIL_ADDRESS] (Y.-H.H.)  
[PERSON]  
2 Department of Communications Engineering, National Chung Cheng University  
allocation to efficiently use the traditionally unusable NPUSCH subframes to increase resource utilization. Specifically, we allow UEs to stop monitoring their search spaces in the next NP while continuously transmitting data in the NPUSCH subframes from the current NP to the next NP without causing any interference. We explain the cross-cycled resource allocation in detail in Section 2.  
Recently, there have been some studies exploring various uplink resource allocation issues in NB-IoT. [PERSON] et al. [4] proposed a method that is divided into inner and outer loops. The inner loop adjusts the number of repetitions to ensure a transmission error rate and reduce resource consumption. The outer loop determines the modulation-coding schemes and the number of repetitions. However, this paper only considers a single tone. Besides, [PERSON] et al. [5] decomposed the problem into uplink scheduling and power allocation to maximize the throughput while maintaining as low latency as possible. [PERSON] et al. [6] designed an algorithm to allocate NPDCCH and NPUSCH resources for multiple coverage enhancement (CE) levels. [PERSON] et al. [7] studied the power and subcarriers allocation to maximize the number of service UEs and meet each UE's needs.  
[PERSON] et al. [8] investigated the influence of scheduling parameters on the resource allocation problem and designed an algorithm to schedule a large number of UEs. [PERSON] et al. [9] proposed an algorithm to control the number of UE connections to increase the probability of successful connections by ensuring that the UEs complete the random access and data transmission processes. [PERSON] et al. [10] considered the use of low-Earth orbit satellites to provide the NB-IoT connectivity to on-ground UEs. [PERSON] et al. [11] investigated the link adaptation problem and designed a heuristic algorithm to minimize the energy consumption. Finally, [PERSON] et al. [12] designed a resource allocation algorithm that considers narrowband physical random access channels (NPRACHs) to minimize the consumed subframes. However, these works do not consider the cross-cycled allocation for NB-IoT and waste many subframes, especially when an NPDCCH period length is short.  
In this paper, we study the cross-cycled uplink resource allocation problem over NB-IoT networks. Our goal is to reduce the number of consumed subframes while satisfying the data request of each UE. The contributions of this paper are summarized as follows.  
* We believe this is the first paper to consider the cross-cycled resource allocation for the uplink in NB-IoT networks.
* We propose a cross-cycled uplink resource allocation algorithm that can use the subframes of the next NP without causing interference.
* We conducted experiments via simulations using realistic settings. Compared with the two resource allocation algorithms [11; 12], the results verify our observation and demonstrate the efficiency of the proposed algorithm, which can reduce more subframes with a smaller NPDCCH period. Moreover, the proposed algorithm can be applied for more different NPDCCH periods.  
The remainder of this paper is organized as follows. In Section 2, we describe the system model and the problem formulation. In Section 3, we explain the proposed algorithm and analyze its properties. Section 4 presents the simulation results. Finally, Section 5 concludes this paper.  
Figure 1: Waste uplink subframes in NB-IoT.