Blanking Gaps in Uplink Cellular UMTS in the IMT-2000 Extension Band to Solve the Bluetooth Coexistence Problem
Markus G. Konrad, Wolfgang Koch · 2006
According to the ECC-PT1 the UMTS (Universal Mobile Telecommunications System) FDD (Frequency Division Duplex) uplink in the 2500-2690 MHz extension band starts at 2500 MHz. Bluetooth (BT) is operated in the 2.4 GHz ISM (industrial, scientific, and medical) band. In [M. Konrad, et al., "Coexistence Analysis of Bluetooth and Cellular UMTS in the 2500 - 2690 MHz Band," in IEEE Wireless Communications and Networking Conference 2006 Proceedings, Las Vegas, NV USA, April 2006.] we have demonstrated that RF blocking is a severe source of interference to the BT technology if both technologies are co-located within the same terminal. Observing that Bluetooth devices transmit short packets followed by long transmission gaps and using the knowledge that the channel coded UMTS uplink spread spectrum signal is inherently robust to short gaps, we introduce the concept of UMTS uplink blanking gaps which refers to switching off the uplink transmission during mobile terminal BT reception as a solution to preventing RF receiver blocking by exploiting convolutional coding (CC) and interleaving. By means of link level simulations the authors demonstrate that the loss due to blanking is comparable to the Eb/No loss of UMTS compressed mode for both 12.2 kbit/s speech and 64.0 kbit/s data services and thus a reasonable solution to ensure coexistence.