WCDMA Modulation

Different modulation methods corresponding to different transmitting abilities in air interface. R99/R4: QPSK HSDPA: QPSK or 16QAM The UTRAN air interface uses QPSK modulation in the downlink, although HSDPA may also employ 16 Quadrature Amplitude Modulation (16QAM). 16QAM requires good radio conditions to work well. As seen, with 16QAM also the amplitude of the signal … Read more

Step of RRC Connection Setup in LTE

Step of RRC Connection Setup in LTE 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 … Read more

WCDMA Radio Interface Channel Definition

Logical Channel = information container  Defined by is transferred. Transport Channel = characteristics of transmission Described by and with data is transmitted over the radio interface . Physical Channel = specification of the information global content providing the real transmission resource, maybe a frequency ,a specific set of codes and phase. In terms of protocol … Read more

Purpose of Channelization Code & Scrambling Code in WCDMA

Purpose of Channelization Code & Scrambling Code in WCDMA Purpose of Channelization Code & Scrambling Code in WCDMA Channelization Codes in WCDMA: Channelization codes, also known as Walsh codes, serve a critical purpose in WCDMA (Wideband Code Division Multiple Access) networks. These codes are used for the spreading of user data over a wide frequency … Read more

Process Gain in WCDMA

How Process Gain works in 3G? Process Gain = 10 Log (Chip rate/Bit Rate) Process gain differs for each service. If the service bit rate is greater, the process gain is smaller, UE needs more power for this service, then the coverage of this service will be smaller, vice versa. For common services, the bit … Read more

Orthogonal Code Usage – Coding & Decoding in WCDMA

How Orthogonal Code works in WCDMA? 1.Coding By spreading, each symbol is multiplied with all the chips in the orthogonal sequence assigned to the user. The resulting sequence is processed and is then transmitted over the physical channel along with other spread symbols. In this figure, 4-digit codes are used. The product of the user … Read more

WCDMA Network Architecture

WCDMA Network Architecture The Wideband Code Division Multiple Access (WCDMA) network architecture: WCDMA (Wideband Code Division Multiple Access) is a 3G cellular network technology that operates on a wideband frequency and offers high-speed data and voice services. The WCDMA network architecture is based on two main components: the Radio Access Network (RAN) and the Core … Read more

Signal Fading

A transmitted signal changes as it travels to the receiver. The effect of these changes is commonly referred to as fading. The fading results from the superimposition of transmitted signals, in which differences in attenuation, delay and phase shift have occurred. Slow fading: In case shadow effect is caused by obstacles, and the receiving signal … Read more

CDMA Channel Frequencies & Calculation

The 850MHz CDMA band is most popularly used all over the world.This band as mentioned in the previous slide works between       824-849MHz Used for the Reverse link communication       869-894MHz Used for the Forward link communication The CDMA band is divided into sub bands as shown above.The Total Band of  25MHz is divided into … Read more

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

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