改进的多信道S-ALOHA暂态性能分析办法及其应用

Improved Transient Performance Analysis Algorithm of Multichannel S-ALOHA and Its Applications

海量机器类终端(或MTC终端)同步入网时,其业务呈现瞬时突发性,这使得基于齐次或复合泊松假设的多信道S-ALOHA稳态性能分析办法难以直接应用。该文以第i个随机接入时隙内第j次进行随机接入的用户数Mi(j)作为状态变量,提出了一种沿Mi(j)的j方向迭代进行多信道S-ALOHA暂态性能分析的办法及其近似形式。该迭代办法可建立第i个随机接入时隙内第j次进行随机接入的用户数与第x个随机接入时隙内新到用户数的直接关系(其中x<i),也可给出接入时延概率密度函数、概率分布函数和均值的求解办法。以3GPP MTC业务参考模型进行数值仿真,验证了所提迭代办法及其近似形式的有效性。相关研究可为承载网络的优化设计提供参考。

Concurrent data transmission from massive Machine Type Communications （MTC） devices makes the traffic pattern of MTC more bursty, which invalidates the commonly-used methodologies of traffic engineering for multichannel S-ALOHA under the assumption of homogeneous or compound Poisson process. By usage of the number of contending devices that transmit thej-th preamble at thei-th Random Access （RA） slot as state variable, an innovative iterative process with its simplified form is proposed to acquire the dynamic process of multichannel S-ALOHA. It reveals the direct relation between the number of contending devices that transmit the j-th preamble at thei-th RA slot and the newly arrived devices beforei-th RA slot. It also presents an analytical way to compute the probability density function, cumulative density function and mean of access delay. Numerical results by the use of MTC traffic models proposed by 3GPP are conducted to validate the effectiveness of the proposed iterative process and its simplified form. These works provide engineers insights to design enhanced overload control mechanism for MTC applications.