Purpose of Channelization Code & Scrambling Code in WCDMA Channelization Codes in WCDMA: Channelization codes, also known as Walsh codes, serve a critical purpose in WCDMA (Wideband Code Division Multiple Access) networks. These codes are used for the spreading of user data over a wide frequency band, which is a fundamental principle of CDMA-based systems … Read more
Message Transmission Mode MS measures the frame quality and informs the base station to the result i.e. whether it is in the threshold or periodical mode. Base station determines whether to change the forward transmitting power or not. In IS-95 system, the forward power control is slow but in CDMA2000 system it is fast. Forward … Read more
In an actual application, the system implements the modulation in this way: as shown above, I and Q channel sequences in the figure represent two channels of cyclic PN short code sequences. The cyclic period of each channel of PN short codes is 215. For different sectors, there are different starting locations of I … Read more
A physical channel is defined by a specific carrier frequency, code (scrambling code, spreading code) and relative phase. In UMTS system, the different code (scrambling code or spreading code) can distinguish the channels. Most channels consist of radio frames and time slots, and each radio frame consists of 15 time slots. Two types of physical channel: UL and … 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
Reverse power control Open loop power control Closed loop power control Inner loop power control: 800 Hz Outer loop power control Forward power control Message transmission mode: threshold transmission periodic transmission Closed loop power control Reverse open loop power control means that based on the detected signals from a base station, a mobile station … Read more
The long code is a PN sequence with period of 242-1chips The functions of a long code: Scramble the forward CDMA channel Control the insertion of power control bit Spread the information on the reverse CDMA channel to identify the mobile stations In a reverse direction, different long codes are used for the information … Read more
It can be seen from the figure that the data are read row by row into an interleaver at the transmit end,read column by column out (this process is called interleaving) and propagated after other modulation process. Then, the data enter the interleaver at the receive end row by row and are read out column … Read more
Logical Channel = information container Defined by is transferred. Transport Channel = characteristics of transmission Described by and with data is transmitted over the radio interface . Physical Channel = specification of the information global content providing the real transmission resource, maybe a frequency ,a specific set of codes and phase. In terms of protocol … Read more
AMR (Adaptive Multi-Rate) Speech A integrated speech codec with 8 source rates The AMR bit rates can be controlled by the RAN depending on the system load and quality of the speech connections Video Phone Service H.324 is used for VP Service in CS domain Includes: video codec, speech codec, data protocols, multiplexing and etc. … Read more