摘要
在监控物联网中,一些感知设备需要在能耗受限条件下及时地将采集信息回传给接入节点(AP),信息年龄(AoI)和能量效率(EE)对系统都很重要。该文研究了多设备监控物联网中时效与能效之间的折衷问题,其中感知设备在智能反射面(IRS)辅助下通过短包传输监控信息给AP。为了避免多个感知设备占用同一资源块导致包的碰撞,该文提出了一个接入控制协议,并推导了平均AoI和EE的闭式表达式。在此基础上,引入了平均AoI和EE之比这个指标,通过优化传输功率来最小化平均AoI和EE之比,以折衷时效性能与能效性能。仿真结果验证了该文理论分析的正确性,并且表明所提协议能够实现更好的时效和能效性能。此外,所提算法能够有效找出最优的时效-能效折衷点。
Objective:In monitoring Internet of Things(IoT)systems,it is essential for sensor devices to transmit collected data to the Access Point(AP)promptly.The timely transmission of information can be enhanced by increasing transmission power,as higher power levels tend to improve the reliability of data transfer.However,sensor devices typically have limited transmission power,and beyond a certain threshold,increases in power yield diminishing returns in terms of transmission timeliness.Therefore,effectively managing transmission power to balance timeliness and Energy Efficiency(EE)is crucial for sensor devices.This paper investigates the trade-off between the Age of Information(AoI)and EE in multi-device monitoring systems,where sensor devices communicate monitoring data to the AP using short packets with support from Intelligent Reflective Surface(IRS).To address packet collisions that occur when multiple devices access the same resource block,an access control protocol is developed,and closed-form expressions are derived for both the average AoI and EE.Based on these expressions,the average AoI-EE ratio is introduced as a metric that can be minimized to achieve an optimal balance between AoI and EE through transmission power optimization.Methods:Deriving the closed-form expression for the average AoI is challenging due to two factors.Firstly,obtaining the exact distribution of the composite channel gain is difficult.Secondly,in short-packet communications,the packet error rate expression involves a complementary cumulative distribution function with a complex structure,complicating the averaging process.However,the Moment Matching(MM)technique can approximate the probability distribution of the composite channel gain as a gamma distribution.To address the second challenge,a linear function is used to approximate the packet error rate,yielding an approximate expression for the average packet error rate.Additionally,to examine the relationship between the ratio of average AoI and EE with transmission power,the second derivative of this ratio is calculated and analyzed.Finally,the optimal transmission power is determined using the binary search algorithm.Results and Discussions:Firstly,the paper examines the division of a time slot into varying numbers of resource blocks and analyzes their AoI performances.The findings indicate that AoI performance does not increase monotonically with an increase in the number of resource blocks.Specifically,while a greater number of resource blocks enhances the probability of device access,it concurrently reduces the size of each resource block,leading to an increase in packet error rates during information transmission.Therefore,it is essential to strategically plan the number of resource blocks allocated for each time slot.Additionally,the results demonstrate that the AoI performance of the proposed access control scheme exceeds that of traditional random access and periodic sampling schemes.In the random access scheme,devices occupy resource blocks at random,which may lead to multiple devices occupying the same block and resulting in transmission collisions that compromise the reliability of information transmission.Conversely,while devices in the periodic sampling scheme can reliably access resource blocks within each cycle,one cycle includes multiple time slots,thus necessitating a prolonged wait for information transmission.Moreover,it is noted that at lower information transmission power levels,the periodic sampling scheme can achieve higher EE.This is attributed to the low transmission power resulting in substantially higher packet error rates across all schemes;however,the periodic sampling scheme manages to secure larger resource blocks,leading to lower packet error rates and a reduced likelihood of energy waste during signal transmission.As information transmission power increases,the advantages of the periodic sampling scheme begin to diminish,and the EE of the proposed access control scheme ultimately exceeds that of the periodic sampling scheme.Finally,the paper investigates the relationship between the ratio of average AoI and EE with the information transmission power.The analysis reveals that this ratio is a convex function that initially decreases and subsequently increases with rising transmission power,indicating the existence of an optimal power level that minimizes the ratio.Conclusions:This study examines the trade off between timeliness and EE in IRS-assisted short-packet communication systems.An access control protocol is proposed to mitigate packet collisions,and both timeliness and EE are analyzed.The ratio of average AoI to EE is introduced as a metric to balance AoI and EE,with optimization of transmission power shown to minimize this ratio.Simulation results validate the theoretical analysis and demonstrate that the proposed access control protocol achieves an improved AoI-EE trade off.Future research will focus on optimizing the deployment location of the IRS to further enhance the balance between timeliness and EE.
作者
张洋译
管新荣
王权
邓诚
朱泽源
蔡跃明
ZHANG Yangyi;GUAN Xinrong;WANG Quan;DENG Cheng;ZHU Zeyuan;CAI Yueming(College of Communication Engineering,Army Engineering University of PLA,Nanjing 210007,China;Unit 32319 of PLA,Urumqi 830002,China;Unit 32579 of PLA,Guilin 541000,China)
出处
《电子与信息学报》
北大核心
2025年第2期315-323,共9页
Journal of Electronics & Information Technology
基金
国家自然科学基金(62171461,62171464)。
关键词
信息年龄
能量效率
短包通信
智能反射面
Age of Information(AoI)
Energy Efficiency(EE)
Short packet communications
Intelligent Reflecting Surface(IRS)
