Research On Low Cost MTC Indoor Coverage Improvement

Machine type of communications (MTC) is defined as Machine to Machine (M2M)communication over the cellular network. It has huge number of devices, many types ofapplications and various kinds of traffic models, which is widely used in intelligenttransportation, smart grid, smart home and other fields. These MTC applications requirethe MTC devices to be located in enclosed spaces, such as the cars or basement. Thismakes both the quality and the coverage of MTC much lower, as these indoor MTCdevices would experience an additional20dB penetration loss on the radio interfacewith respect to non-indoor MTC devices. The long term evolution (LTE) networkproposed by the third generation partnership project (3GPP) has high spectral efficiency,high reliability and wide coverage, which makes a primary bearing network of MTC.Current power control technology in LTE could compensate the pass loss of non-indoorMTC devices, but still can’t meet the requirement of the additional20dB attenuation ofthe indoor MTC devices. The technologies suited for Human to Human (H2H)communication, such as increasing the bandwidth, boosting the maximum transmissionpower, utilizing the uplink MIMO technology and improved coding method, canpartially compensate the attenuation of indoor MTC signal, but they increases the costof the device, which conflicts with the low-cost and low-power requirements of MTC.To guarantee the coverage of these indoor MTC devices, in this paper, we firstpropose a discrimination mechanism to differentiate them from MTC devices, whichpossess good stability and strong adaptability. Once identified the indoor MTC devices,we adopt dedicated compensation mechanisms to compensate the additional penetrationloss of the indoor MTC devices.These works together can provide references for uplink coverage enhancement forindoor MTC applications.The main contributions are as follows:①A discrimination mechanism to differentiate the indoor MTC devices isproposed. The mechanism discriminates the application environments in spacial andtemporal domains. The differentiating algorithm in spacial domain takes advantage ofthe bivariate classification methodology, which distinguish these two types of devicesthrough an optimal pass loss threshold. Meanwhile, In temporal domain, devicesdetermine their application environments though the “and operation” of the decisions in multiple time instants, and then dynamically adjust the optimal threshold. Numericalresults show that the proposed discrimination mechanism can effectively identifies theindoor MTC devices which under Rayleigh fading, at the same time avoids the waste ofresources caused by power compensation for all devices. When the additionalpenetration loss of the indoor MTC devices reaches20dB or higher, discriminant errorprobability is less affected by the proportion of MTC indoor device, its value at about3%.②An indoor MTC dedicated power compensation mechanisms is proposed. Theworking process of this scheme is that when transmission power of the indoor MTCdevices is less than the maximum transmission power, we can increase the transmissionpower according to the retransmission times; when transmission power is equal to themaximum transmission power, we can utilize the TTI Bundling time diversity, whichmeans we can distribute continuous TTI for the indoor MTC devices and send differentredundancy versions of data. And thus the receiver will combine the data beforedecoding in order to improve the precision of the data transmission. Numerical resultsshow that the dedicated compensation mechanisms can obtain1-5dB gain, partlycompensates for the additional penetration loss of the indoor MTC devices and improvethe coverage of indoor MTC.