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Downlink Logical Channel in GSM

In 2G GSM Technology in forward direction Downlink (GSM BTS to GSM Mobile). There are mainly five Downlink Logical Channel in GSM. Frequency correction channel (FCCH) Synchronous channel (SCH) Broadcast control channel (BCCH) Paging channel (PCH) Access granted channel (AGCH) Frequency correction channel (FCCH) First start with FCCH which full form is frequency correction channel … Read more

DL & UL Physical Channel in LTE

How Physical channel of LTE works in UL & DL?A distinction has to made between:  The Physical channel The Physical signal The DL physical channels are: Physical DL Shared Channel (PDSCH) It is a shared channel used to carry user data, radio & core network, system information (BCH), paging message. Physical DL Control Channel (PDCCH) … Read more

From the Transport to the Physical Channel in LTE

Transport channels are then mapped on the physical channels which are sent over the air interface A CRC is calculated and appended to each TB. It allows the receiver to detect errors. It is used by retransmission mechanisms like H-ARQ Depending on the Transport Format and the radio quality, the TB is coded and interleaved. … Read more

How Transport Channel Work in LTE?

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

How Many Logical Channel in LTE ?

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

WCDMA Interleaving

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

WCDMA Channel Coding

Effect Enhance the correlation among symbols so as to recover the signal when interference occurs Provides better error correction at receiver, but brings increment of the delay Channel Types No Coding Convolutional Coding (1/2, 1/3) Turbo Coding (1/3)   UTRAN employs two FEC schemes: convolutional codes and turbo codes. The idea is to add redundancy … Read more

Which Bands Used in WCDMA ?

There are different band in different country but most of commonly used band we will discuss here. Main bands : means basic band when 3G commercial launch by Private or public sector. 1920 ~ 1980MHz / 2110 ~ 2170MHz Supplementary bands: different country maybe different as per government selling in auction. 1850 ~ 1910 MHz / 1930 MHz … Read more

How MAC Protocol Work In LTE?

The MAC protocol provides the following services: Logical Channel to Transport channel mapping Scheduling: There is no dedicated channel allocated to a UE. Time and frequency resources are dynamically shared between the users in DL and UL. The scheduler is part of the MAC layer and controls the assignment of uplink and downlink resources. Multiplexing/Demultiplexing … Read more

Radio Link Control (RLC) protocol services in LTE

The Radio Link Control (RLC) protocol provides the following services: Segmentation of SDU according to the size Re-Segmentation of PDU Radio Bearer to logical channel mapping Transfer of data in 3 modes: TM Transparent Mode Without retransmission. For real-time service. UM Unacknowledged Mode Without retransmission, but error statistics (BLER) It can be used for the … Read more