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
LTE SC-FDMA and LTE Uplink LTE (Long-Term Evolution) utilizes a specific modulation scheme for the uplink known as Single-Carrier Frequency Division Multiple Access (SC-FDMA). SC-FDMA is a modulation and access scheme that provides advantages for uplink transmission in LTE networks. Introduction to SC-FDMA and uplink frame structure Marriage of single carrier transmission and FDMA Uplink … Read more
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 Access). OFDMA is a variant of OFDM which has the advantage that receiver complexity is at a reasonable level, it can handle scalable bandwidth requirements … Read more
FDM in LTE Conventional multi-carrier operation as it is used for FDM works simply by selecting a number of center frequencies – one for each carrier to be used. The center frequencies must be spaced. In fact there is a trade-off between minimizing interference between different carriers and using the total bandwidth efficiently. In other … Read more
Sub-Carrier Allocation Mode 1 DL PUSC – Downlink partial Usage Sub-Channels The downlink PUSC replacement zone is unique, that must exist in the frame structure specified by the protocols. DL PUSC with all SC – PUSC with all sc indicates the PUSC replacement mode when all the bandwidth resources are used. DL FUSC- Downlink Full … Read more
A data-modulation scheme defines how the data bits are mixed with the carrier signal, which is always a sine wave. There are three basic ways to modulate a carrier signal in a digital sense: amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK). In ASK the amplitude of the carrier signal … Read more
BCCH(Broadcast Control Channels) Downlink Only. Broadcast information of the serving cell (System Information). Transmitted on timeslot zero of BCCH carrier. Read only by idle mobile at least once every 30 secs. SCH (Synchronization Channels) Downlink Only Carries information for frame synchronization. Contains frame number and BSIC (Base Station Identity Code). FCCH (Frequency Correction Channels) Downlink … Read more
As shown above, CCCH=PCH+RACH+AGCH; downlink CCCH=PCH+AGCH; and uplink CCCH=RACH. In the above combinations, combination 3 and 4 must be allocated to slot 0 of the BCCH carrier configured for the cell; while combination 5 must be allocated to timeslots 2, 4 and 6 of the BCCH carrier. The FACCH works in the frame stealing mode, … Read more
There are two ways to transmit training symbols: preamble or pilot tones. Preambles entail sending a certain number of training symbols prior to the user data symbols. In the case of OFDM, one or two preamble OFDM symbols are typical. Pilot tones involve inserting a few known pilot symbols among the subcarriers. Channel estimation in … Read more