SCH Supplemental channel (CDMA2000)

The SCH (Supplemental Channel) is a key component in the CDMA2000 (Code Division Multiple Access 2000) wireless communication system. CDMA2000 is a set of standards developed to enhance and expand the capabilities of the earlier CDMA technology used in 2G networks.

In CDMA2000, the SCH is used to carry signaling information and provide additional capacity for data transmission. It operates in parallel with the primary traffic channel, known as the Fundamental Channel (FCH), which carries voice and data traffic.

Here are some key points to understand about the SCH in CDMA2000:

Purpose:

The SCH serves multiple purposes within the CDMA2000 system, including:

a. Signaling: It carries signaling information for call setup, handoffs, power control, and other control functions between the mobile device (user equipment) and the base station (Node B).

b. Data Capacity: The SCH provides additional capacity for transmitting user data. It helps increase the overall data throughput of the system.

c. Power Control: The SCH is also used for power control purposes, allowing the base station to adjust the transmission power of the mobile device dynamically.

Channel Structure:

The SCH operates in a dedicated channel within the CDMA2000 air interface. It is a time-multiplexed channel that shares the same frequency resources as the FCH. The SCH is divided into time slots, and each time slot carries a certain amount of signaling or data information.

Forward and Reverse Link:

CDMA2000 uses a duplex communication scheme, meaning that there are separate channels for the forward link (base station to mobile device) and the reverse link (mobile device to base station). Both the forward and reverse links have their own SCHs.

a. Forward Link SCH (FSCH): The FSCH is transmitted from the base station to the mobile device. It carries signaling information and additional data capacity for downstream transmission.

b. Reverse Link SCH (RSCH): The RSCH is transmitted from the mobile device to the base station. It carries signaling information and provides additional data capacity for upstream transmission.

Modulation and Coding: The SCH in CDMA2000 uses various modulation and coding sche

mes to optimize the transmission efficiency and robustness. The modulation schemes include BPSK (Binary Phase-Shift Keying) and QPSK (Quadrature Phase-Shift Keying). The coding schemes employ convolutional coding and turbo coding techniques.

Channel Configuration:

The configuration of the SCH in CDMA2000 is determined by the system parameters and network planning. The number of SCH time slots, the data rate per time slot, and the power allocation can vary based on the specific requirements of the network and the traffic demands.

Overall, the SCH in CDMA2000 plays a crucial role in facilitating signaling, enhancing data capacity, and supporting power control in the system. It is an integral part of the CDMA2000 air interface, providing the necessary resources for efficient and reliable communication between mobile devices and base stations.