The former CEO at South Africa’s MTN Group has denied claims that he authorised the payment of bribes to government officials to help secure a GSM operator license in Iran. The company is currently being sued by Turkcell after it claims that its license was confiscated and awarded to MTN after bribes were paid by … Read more
The PDCCH, Physical Downlink Control Channel, allocates the DL and UL resources. There is one PDCCH per sub-frame. It helps the UE retrieve the transport blocks from the PDSCH: Allocated RB Modulation and Coding Scheme (MCS) Multi-antenna transmission PDCCH Shared between all UE of the cell Each TTI contains an aggregation of PDCCH allowing … Read more
A transport channel defines how and with what characteristics the information is transmitted. Inherited from the WCDMA, data on the transport channel is organized into “Transport Blocks”, TBs. A Transport block can be transmitted every TTI = 1 ms The “Transport Format”, TF, defines how the blocks can be transmitted: Transport block size, it depends … Read more
The following control logical channels have been defined by the 3GPP: BCCH, Broadcast Control Channel, used for the transmission of system control information. A UE needs to decode it before requesting a connection. PCCH, Paging Control Channel, is a downlink channel that transfers paging information and system information change notifications. This channel is used for … Read more
In the C-plane, the NAS functional block is used for network attachment, authentication, setting up bearers, and mobility management. All NAS messages are ciphered and integrity protected by the MMEand UE. The radio resource control (RRC) layer in the eNB makes handover decisions based on neighbor cell measurements reported by the UE, performs paging of … Read more
How OFDMA Transmitter in LTE ? In the downlink, OFDM is selected to efficiently meet E-UTRA performance requirements. With OFDM, it is straightforward to exploit frequency selectivity of the multi-path channel with lowcomplexity receivers. This allows frequency selective in addition to frequency diverse scheduling and one cell reuse of available bandwidth. Furthermore, due to its … Read more
In FDM, the sub-carriers are separated in the frequency domain to avoid interference between the sub-channels It results in a loss of spectrum efficiency because the frequency guard band can not be used to send data. The OFDM allows one to remove the frequency guard band. Benefit: There are more sub-carriers, so more symbols … Read more
All MS transmit on same frequency but with different PN codes to create different logical channels. Some channels marked for Access are used for signaling and control. While Walsh Codes identifies different channels, PN codes are used to identify Cells (by 15 bit code) and MS’s (by 42 bit codes). As each MS receives a … Read more
Adopting a multicarrier approach for multiple access in LTE was the first major design choice. The choice of multiple-access schemes was made in December 2005, with OFDMA being selected for the downlink, and SC-FDMA for the uplink. Both of these schemes open up the frequency domain as a new dimension of flexibility in the system, … Read more
SC-FDMA utilizes single carrier modulation, DFT-spread orthogonal frequency multiplexing, and frequency domain equalization. LTE uses OFDMA on the DL. It allocates DL bandwidth to the user based on resource blocks, rather than individual subcarriers. When the signal is a combination of subcarriers, high amplitude power peaks can occur. The base stations power amplifiers are designed … Read more