## Codewords and Layers and Ports

We throw a lot of terms around when we discuss LTE data transmissions, especially when we get into some of the details of sending data over the PDSCH using multiple antenna techniques. We describe transport blocks as holding the data we’re trying to send, but how do they relate to codewords? Assigning bits to different layers can be used to improve reliability or throughput, but are layers the same as antenna ports? Let’s have a closer look at what’s going on down in the Physical (PHY) Layer.

User data and signaling messages are processed by the PDCP, RLC and MAC layers before being passed down to the PHY layer to be sent over the air. A lot happens to a data packet before PHY gets it, but for the moment, let’s just treat the MAC PDU (Protocol Data Unit) that PHY receives from MAC as “data”. To PHY, it’s just a string of bits anyway. This will be our transport block. Read more

# 星座映射归一化因子是如何得到的

## Difference Between Modulo and Complementation Operation

Modulo and Complementation operation are partially same. This article will expalin their difference.

The way to compute Modulo and Complementation (m = a mod b or m = a % b) is as follows:

Step 1: Compute c = a / b;

Step 2: Compute m = a - b * c. Read more

## CRC字节算法

1、 原始序列要左移n位，再除以生成多项式；

2、生成多项式所包含的比特数比CRC校验比特数多1。

## LTE易忘点

1、FDD frame structure

## LTE 开发平台 – FQA

1. 哪一个工程需要配置commonc\common？如何配置？

2. target-configuration 配置

# 下载用的target configuration

## 步骤：

• Step 1：在CCS 5.3中将界面切换到CCS Debug，这个按钮在软件界面的右上角。如果没有，请点击”CCS Edit”左边的添加按钮，将CCS Debug加上去。按钮如下图所示。

## LTE系统中RB、RBG、CCE、REG分别是如何定义的

RE：Resource Element，称为资源粒子，是上下行传输使用的最小资源单位。1 RE = 1 subcarrier * 1 symbol period.

RB：Resouce Block，称为资源块，用于描述物理信道到资源粒子的映射。一个RB包含若干个RE，一个RB由12个在频域上的子载波和时域上一个slot周期构成的（1RB = 12 subcarriers * 1 slot）。

• 1个RB在频域上对应180kHz，1 RB = 12 subcarriers * 15kHz = 180 kHz。
• 1个RB在时域上对应一个时隙，1 slot = 0.5 ms。

## LTE学习杂记

1、当信号带宽大于相干带宽时，会发生频率选择性衰落。

## LTE : 传输信道和逻辑信道、物理信道的区别

The physical layer offers information transfer services to MAC and higher layers. The physical layer transport services are described by how and with what characteristics data are transferred over the radio interface. An adequate term for this is “Transport Channel“.

NOTE: This should be clearly separated from the classification of what is transported, which relates to the concept of logical channels at MAC sublayer.