The radio waves are distributed in 3Hz ~ 3000GHz. This spectrum is divided into 12 bands, as shown in the above table. The frequencies in each specific band present unique propagation features: The lower the frequency is, the lower the propagation loss will be, the farther the coverage distance will be, and the stronger the … Read more
Radio wave can be propagated from the transmitting antenna to the receiving antenna in many ways: perpendicular incidence wave or ground refraction wave, diffraction wave, troposphere reflection wave, ionosphere reflection wave, as shown in the diagram. As for radio wave, the most simple propagation mode between the transmitter and the receiver is free space propagation. … Read more
Transmit Diversity MISO = Multiple Input Single Output Principle More complex than SISO. 2 or more transmitters and one receiver. MISO is more commonly referred to as transmit diversity. The same data is sent on both transmitting antennas but coded in such a way that the receiver can identify each transmitter. Benefits Transmit diversity increases … Read more
Adaptive Multi-Rate (AMR) codec consists of a family of codecs (source andchannel codecs with different trade-off bit-rates) operating in the GSM FRand HR channels modes The AMR system exploits the channel performance and robustness added bythe coding rates by adapting the speech and channel coding rates accordingto the quality of the radio channel AMR adapts … Read more
After the power on, the UE knows: the UE category and capability. the preferred PLMN. the carriers. The UE needs to know: The frame synchronization to be able to decode the DL radio frame. The cell parameters to be able request a connection. The UE can use: The PSS: Primary Synchronization Signal. The SSS: Secondary … Read more
When the UE has obtained system information, it has to request an RRCconnection. Like it has no dedicated resources, the UE requests the connection using the Random Access Procedure using common uplink resources. At the end of the procedure, the UE is RRC connected UE and eNodeB are able to exchange data using dedicated radio … Read more
When the UE is powered up, it has to be RRC connected to be able to exchange data and signaling with the network. After the RRC connection, the Initial network attach allows to establish all the bearers to carry the data from the UE to the gateway. After the RRC connection, Signaling Radio Bearers (SRBs) … Read more
1. The Transport block is transmitted to the UE on the PDSCH. 2. The UE receives it but it is erroneous. The TB is stored in a buffer. 3. The UE transmits directly a NACK concerning the erroneous block on the PUCCH. One HARQ entity in the UE and the e-UTRAN Made of 8 HARQ … Read more
The radio retransmission mechanism is called Hybrid Automatic Request (H-ARQ). H-ARQ allows to retransmit fastly erroneous blocks between the eNodeB and the UE. It avoids long retransmission between 2 TCP layers. The H-ARQ process runs in the eNodeB and in the UE. The H-ARQ is based on ACK/NACK messages carried by PUCCH or PUSCH. The … Read more
How WCDMA Interleaving ? Effect Interleaving is used to reduce the probability of consecutive bits error Longer interleaving periods have better data protection with more delay Channel coding works well against random errors, but it is quite vulnerable to bursts of errors, which are typical in mobile radio systems. The especially fast moving UE in … Read more