LTE Parameters and Downlink Modulation LTE (Long-Term Evolution) utilizes various parameters and downlink modulation schemes to optimize data transmission over the wireless network. LTE parameters and frequency bands What is OFDMA? OFDMA multiple access and downlink frame structure OFDMA transmit and receive chains Here are some important parameters and downlink modulation techniques used in LTE: … Read more
A parallel 3GPP R8 project to LTE and SAE is the Evolved High Speed Packet Access, eHSPA, project (also referred to as HSPA+). The proposed eHSPA features represent a logical evolution from today’s HSDPA and HSUPA systems. Roughly speaking, the eHSPA project focuses on three areas: • Optimising HSPA for real-time packet data services, like … Read more
A (rather long) list of general requirements has been set up as guidelines for the standardization work related to the EPC. Some of those are: • 3GPP and non-3GPP access systems shall be supported. • Scalable system architecture and solutions without compromising the system capacity (e.g. by separating CP from UP). • CP response time … Read more
Figure shows the network architecture of the Evolved Packet Core (EPC). The EPC consists of three main nodes: the Mobility Management Entity (MME), the Serving Gateway (SGW) and the Packet Data Network Gateway (PGW). The MME may be co-located with the SGW, and the SGW may be co-located with the PGW. Hence, the standard allows … Read more
The uppermost evolution track shown in Figure is that developed in the 3rd Generation Partnership Project (3GPP), which is currently the dominant standards development group for mobile radio systems and is described in more detail below. Within the 3GPP evolution track, three multiple access technologies are evident: the ‘Second Generation’ GSM/GPRS/EDGE family1 was based on … Read more
Radio wave can be propagated from the transmitting antenna to the receiving antenna in many ways: perpendicular incidence wave or ground refraction wave, diffraction wave, troposphere reflection wave, ionosphere reflection wave, as shown in the diagram. As for radio wave, the most simple propagation mode between the transmitter and the receiver is free space propagation. … Read more
When the radio wave propagates in the air, the electric field direction changes regularly. If the electric field direction of radio wave is vertical to the ground, the radio wave is vertical polarization wave If the electric field direction of radio wave is parallel with the ground, the radiowave is horizontal polarization wave Propagation of … Read more
The radio waves are distributed in 3Hz ~ 3000GHz. This spectrum is divided into 12 bands, as shown in the above table. The frequencies in each specific band present unique propagation features: The lower the frequency is, the lower the propagation loss will be, the farther the coverage distance will be, and the stronger the … Read more
PN Code Generation PN Code Generation PN codes are generated from prime polynomials using modulo 2 arithmetic. The state machines generating these codes are very simple and consist of shift registers and XOR gates . Masking will cause the generator to produce the same sequence, but offset in time PN Offset (Masking) Masking … Read more
• Definition: Orthogonal functions have zero correlation. Two binary sequences are orthogonal if the process of “XORing” them results in an equal number of 1’s and 0’s. Example: 0000 (XOR) 0101 —— 0101 • Generation Sequence: – Seed – Repeat: right & below – Invert: diagonally The above table of … Read more