Uplink data transmission in LTE The mapping of transport channels and UL control information (UCI) to physical channels is a task of the physical layer (PHY). Furthermore reference signals are provided by the physical layer which do not transfer any higher layer information. Logical channel mapping is provided by the MAC layer. Physical channel for … Read more
What is SC-FDMA and how it works in LTE? One of the major drawbacks of an OFDMA system is, that the transformation of a complex symbol mapped sequence (e.g. BPSK, QPSK, etc.) onto a small set of subcarriers produces time sequences that have high PAPR (Peak-to-Average Power Ratio). PAPR is the ratio between the maximum … Read more
Radio Protocol Architecture in LTE The EUTRAN radio protocol model specifies the protocols terminated between UE and eNB. The protocol stack follows the standard guidelines for radio protocol architectures (ITU-R M1035) and is thus quite similar to the WCDMA protocol stack of UMTS. The protocol stack defines three layers: the physical layer (layer 1), data … Read more
Different Tasks and States of RRC Protocol in LTE-EUTRAN The RRC protocol for EUTRAN is responsible for the basic configuration of the radio protocol stack. But one should note, that some radio management functions (scheduling, physical resource assignment for physical channels) are handled by layer 1 and layer 2 autonomously. MAC and layer 1 signaling … Read more
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: (1) an entity that desires to get access: the supplicant, (2) an entity that controls the access gate: the … Read more
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 via dynamical scheduling onto resource blocks. Thus physical channels also in EUTRAN represent the available physical resources. Like transport channels, … Read more
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 in general have variable size. Typically the number of transport blocks that can be transmitted in a TTI depends … Read more
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 control. QoS policy management is about defining and provisioning the various levels and types of QoS services, as well as … Read more
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), data link layer (layer2), and the network layer (layer3). In the E-UTRAN layer 2 is divided into two sub-layers: … Read more
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) / single antenna case. During the initial cell search, the mobile station searches for the strongest cell. It then … Read more