[Requested Talk] Performance of a Small Size Sensing Device under Interference Produced by Secondary Users

摘要

In addition to the completed standards of ECMA-392 and IEEE 802.22-2011, some more systems that target at operating in TV white space (TVWS) are under standardization, namely include IEEE P802.11af, IEEE P802.15.4m and IEEE P1900.7. Therefore, it is foreseeable situation that heterogeneous systems will coexist in the TVWS and which makes it difficult to set universal quiet period among the systems during spectrum sensing. As a result, when spectrum sensing is used to identify TVWS, sensing under interference produced by either of above secondary users (SU) may be the true situation. In this work, experimental study of sensing under SU interference is performed using a recently developed sensing device and IEEE 802.11af prototypes. The sensing device operates at the whole Japanese UHF TV band (470-770 MHz) and can reliably detect the presence of ISDB-T signals at FCC required level of -114 dBm in a 6MHz channel under reasonable adjacent channel interference (ACI) and Doppler frequency. The IEEE 802.11af prototype verifies the PFY and MAC layer design of the specification of IEEE 802.11af draft standard. During experiment, sensing performance is checked for purposely broadcasted on air ISDB-T signals under three noise condition: environment noise without SU interference, under interference produced by a single SU and under aggregate interference produced by two Sus. The test results show that for the feature detection based sensing device, the SU interference produced by IEEE 802.llaf systems may lead to unstable sensing performance when its level is significantly higher than ISDB-T; moreover, the aggregate SU interference does not necessarily lead to worse performance as compared to interference produced by a single SU.