Electronics and Telecommunications Research Institute

Bub Joo Kang

Kwang Roh Park

Sangsung Choi

Kyu Min Kang

Myung Sun Song

Chang Joo Kim

Hyun Seo Oh

Jeong Goo Lee

Chae Kyu Kim

Jae Ryong Shim

Eung Bae Kim

Chae Min Park

A method of assigning a frequency channel using efficient spectrum sensing in a multiple Frequency Assignment system includes a channel sensing process, wherein a base station of a secondary user classifies multiple frequency channels licensed to a primary user into a plurality of channel state sets according to usage states, periodically senses channel states by changing a sensing period according to the types of classified channel state sets, and manages the sensed channel states as frequency channel state set information; a channel state set broadcasting process; and a channel assigning process. Accordingly, a frequency channel can be assigned to a secondary user requesting channel assignment using frequency channel state set information without a primary user experiencing interference noise.

Method of frequency channel assignment using effective spectrum sensing in multiple frequency assignment system

An FIR filter of a DS-CDMA UWB modem transmitter and a control method thereof are disclosed. The FIR filter includes an LUT control device for outputting a resultant value of '0' to all adders if data values corresponding to upper three chips HMand Land lower three chips H, M and L are '000000', and discriminating which group between a first group and a second group the upper/lower data values belong to if the upper/lower data values are not&#x201c;000000&#x201d;. The LUT control device provides upper or lower LUT values to the adders using the upper or lower LUT values as they are, or converts the upper or lower LUT values into 2's complements and provides the converted values to the adders according to the discriminated first or second group.

FIR filter of DS-CDMA UWB modem transmitter and control method thereof

Provided is a method of assigning a frequency channel using efficient spectrum sensing in a multiple Frequency Assignment (FA) system. The method includes a channel sensing process, wherein a base station (BS) of a secondary user classifies multiple frequency channels licensed to a primary user into a plurality of channel states by changing a sensing period according to the types of classified channel state sets, and manages the sensed channel states as frequency channel state set information; a channel state set broadcasting process, wherein the BS transmits the frequency channel state set information managed in the channel sensing process to secondary user terminals using a broadcast message; and a channel assigning process, wherein if the BS receives a channel assignment request message from a new secondary user terminal which has received the broadcast message, the BS assigns an unused frequency channel from among frequency channels licensed to the primary user to the new secondary user terminal using the frequency channel state set information. Accordingly, a frequency channel can be assigned to a secondary user requesting channel assignment using frequency channel state set information without a primary user experiencing interference noise.

Provided are an initial synchronization acquiring device and method in a parallel processed DS-CDMA UWB system and a DS-CDMA UWB system's receiver using the same. The initial synchronization acquiring device is constructed to include a correlator for correlating input signals and outputting correlation result values and an initial synchronizer for tuning initial symbol synchronization and frame synchronization by using the correlation result values received from the correlator and then storing combining mark values and a synchronization position value in a register, thereby making it possible to greatly decrease a system's complexity, compared to the existing method of separately designing respective modules for acquiring packet synchronization and symbol synchronization in the existing CDMA system. Also, the initial synchronization acquiring device and method additionally compensates a synchronization error caused by a frequency offset generated between clocks used by a transmitter and a receiver and thereby can be efficiently used in the high-speed and parallel-processed DS-CDMA UWB system.

Initial synchronization acquiring device and method for parallel processed DS-CDMA UWB system and DS-CDMA system's receiver using the same

An FIR filter of a DS-CDMA UWB modem transmitter and a control method thereof are disclosed. The FIR filter includes an LUT control device for outputting a resultant value of '0' to all adders if data values corresponding to upper three chips H, Mand Land lower three chips H, M and L are '000000', and discriminating which group between a first group and a second group the upper/lower data values belong to if the upper/lower data values are not&#x201c;000000&#x201d;. The LUT control device provides upper or lower LUT values to the adders using the upper or lower LUT values as they are, or converts the upper or lower LUT values into 2's complements and provides the converted values to the adders according to the discriminated first or second group.

There is provided a code acquisition device and method using a two-step search process in a DS-CDMA UWB modem. The device includes: an I/Q channel symbol generating unit for, generating a plurality (i) of nI/Q channel symbols in a first search process and generating a plurality of nI/Q channel symbols in a second search process; a spread code selecting unit for receiving the plurality of nI/Q channel symbols in the first search process; an NNtap I/Q channel symbol matched filter unit for, in the second search process, receiving the plurality (i) of nI/Q channel symbols; a switching unit for changing to a closed state of the second search process; and a super frame and symbol boundary time deciding unit for deciding a super frame time and a symbol boundary time.

Code acquisition device and method using two-step search process in DS-CDMA UWB modem

Generally, Reed-Solomon encoding process in the conventional communication system is executed by a Reed-Solomon encoder having different code rates for different data transmission rates. The present invention does not use a Reed-Solomon encoder having different coding rates, but instead uses a Reed-Solomon encoder having the same code rate regardless of data transmission rate. Accordingly, the present invention has the following effects. The present invention maintains same communication quality regarding data services having each different data transmission rate, and can use a single Reed-Solomon encoder.

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Taejon, South Korea

Bub Joo Kang