Authentication and Access Control in Wimax

Access control is the security mechanism to ensure that only valid users are allowed access to the network. In the most general terms, an access control system has three elements:

Physical Channel Types of LTE

The physical layer uses resource blocks to transmit binary coded information in QPKS, 16QAM or 64QAM or OOK modulation form. Physical channels determine how data is processed and then mapped

How Transport Channel Processing in LTE?

Transport channels are block oriented transmission services and transmit one or more transport blocks per transmission time interval (TTI). The TTI is 1 ms (e.g. one sub-frame). Transport blocks may

QoS Mechanisms in Packet Networks

There are Three Types of QoS Mechanisms in Packet Networks. Control Plane Mechanisms Data Plane Mechanisms Its Tradeoffs Control Plane Mechanisms Such mechanisms include QoS policy management, signaling, and admission

MIMO Principles

The basic mechanism behind MIMO is linear algebra. If we e.g. transmit N (=2) signals S0, S1 via two antennas and receive the signal at M (=2) antennas R0, R1

Layer and channel relationship in LTE

The radio interface is composed of different layers in order to set up, reconfigure and release the radio bearer services. The protocol layer is composed of physical layer (layer 1),

Synchronization in LTE Mobile “Switch On”

Primary and Secondary Synchronization Signals occupy 2 blocks of symbols per 10 ms (central 72 subcarriers for all channel bandwidths). An example is shown below for 72 subcarrier- (1.4 MHz)

How to LTE Radio Air Interface?

The state-of-the-art design of the LTE air interface is characterised by OFDMA (DL) and SC-FDMA (UL) together with MIMO. The downlink modulation is based on OFDMA (Orthogonal Frequency Division Multiple

Pulse shaping and spectrum in LTE

RF engineering is a trade off between: required radio spectrum (bandwidth), speed of data transmission (bit rates) and complexity of implementation. The pulse form used to modulate complex data symbols

Inter-Carrier Interference for OFDM

The price for the optimum subcarrier spacing is the sensitivity of OFDM to frequency errors. If the receiver’s frequency is some fractions of the subcarrier spacing (subcarrier bandwidth) then we

OFDM implementation in Detail

A typical OFDM transmitter is shown on the following figure. To reduce the amount of RF hardware required for OFDM the modulation process is split into two parts. A first