# US 8,787,260 B2 · Adaptively controlling prefix length > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,260 B2 - Document ID: US8787260B2 - Status: Granted - Kind: B2 - Application number: 13/447,349 - Filed: 2012-04-16 - Published: 2012-10-18 - Granted: 2014-07-22 - Earliest claimed: 2011-04-15 - Assignees: Kt Corporation - Applicants: Tae-Won Ban; Chang-Yong Ahn; Sung-Sang You; Hyun-Beom Lee; Hee-Jun Lee; Byoung-Jin Choi - Inventors: Tae-Won Ban; Chang-Yong Ahn; Sung-Sang You; Hyun-Beom Lee; Hee-Jun Lee; Byoung-Jin Choi - Web page: https://patentgrep.com/patent/US8787260B2 ## CPC - H04W 8/26: Network addressing or numbering for mobility support - H04W 84/045: {using private Base Stations, e.g. femto Base Stations, home Node B} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Provided are apparatus and method for setting a cyclic prefix length according to a type of a base station. The apparatus may include a memory, a receiver, a selector, and an inserter. The receiver may be configured to store and to manage a plurality of prefix lengths associated with base station types. The receiver may be configured to receive base station information from a base station. The selector may be configured to select a prefix length from the plurality of prefix length based on the received base station information. The inserter may be configured to insert a cyclic prefix having the determined prefix length in a guard interval of a transmission frame. ## Claims ### Claim 1 A method for adaptively setting a prefix length in communication with a base station, the method comprising: receiving base station information from the base station; determining the prefix length based on the received base station information; and inserting a cyclic prefix in a transmission frame with the determined prefix length, wherein the determining includes: determining a type of the base station based on the received base station information; and setting the prefix length according to the type of the base station, and wherein the setting the prefix length includes: setting a comparatively short prefix length when the type of the base station is a femtocell base station; and setting a comparatively long prefix length when the type of the base station is a macrocell base station. ### Claim 2 (depends on 1) The method of claim 1, wherein the determining the type of the base station is based on at least one of a base station identifier, a cell identifier, and a zone indicator, included in the received base station information. ### Claim 3 (depends on 1) The method of claim 1, wherein the inserting the cyclic prefix includes: copying a portion of a symbol of the determined prefix length; and inserting the copied portion in a guard interval of the transmission frame. ### Claim 4 (depends on 3) The method of claim 3, wherein a length of the guard interval is maintained constantly regardless of the determined prefix length. ### Claim 5 (depends on 1) The method of claim 1, wherein the cyclic prefix is a cyclic prefix of an OFDM wireless communication system. ### Claim 6 A method for adaptively setting a prefix length in communication with a base station, the method comprising: receiving base station information from the base station; determining the prefix length based on the received base station information; and inserting a cyclic prefix in a transmission frame with the determined prefix length, wherein the determining the prefix length includes: determining a communication distance of the base station based on the received base station information; and setting the prefix length differently according to the determined communication distance of the base station. ### Claim 7 (depends on 6) The method of claim 6, wherein the setting the prefix length includes: setting a comparatively short prefix length when the communication distance is comparatively short; and setting a comparatively long prefix length when the communication distance is comparatively long. ### Claim 8 (depends on 6) The method of claim 6, wherein the communication distance is determined based on at least one of transmission power of the base station, a cell radius of the base station, delay spread in a cell of the base station, and a cell identifier of the base station, which are included in the received base station information. ### Claim 9 A method for adaptively setting a prefix length, the method comprising: receiving base station information from a base station; selecting at least one from a plurality of prefix lengths based on the received base station information; and inserting a cyclic prefix in a transmission frame with the selected prefix length and transmitting signals using the transmission frame, wherein: the received base station information includes information of at least one of transmission power, a cell radius, a base station identifier, a cell identifier associated with the base station, delay spread in a cell of a base station, and a zone indicator. ### Claim 10 The method of 9, prior to the receiving, further comprising: determining the plurality of prefix lengths according to a type of the base station; and storing the plurality of determined prefix lengths associated with each type of base station in a memory. ### Claim 11 (depends on 10) The method of claim 10, wherein the selecting includes: determining a type of the base station based on the received base station information; and selecting as the prefix length a prefix length associated with the determined type of the base station from the plurality of prefix lengths stored in the memory. ### Claim 12 (depends on 10) The method of claim 10, wherein the plurality of prefix lengths are stored as a prefix length set, the method comprising mapping each prefix length to each type of a base station. ### Claim 13 (depends on 10) The method of claim 10, wherein the determining includes: determining a comparatively short prefix length for a femtocell base station and mapping the comparatively short prefix length to the femtocell base station; and determining a comparatively long prefix length for a macrocell base station and mapping the comparatively long prefix length to a macrocell base station. ### Claim 14 (depends on 13) The method of claim 13, wherein the selecting includes: determining a type of the base station based on at least one of a cell identifier, a base station identifier, and a zone indicator, which are included in the received base station; and finding a prefix length mapped to the determined type of the base station from the plurality of prefix lengths stored in the memory. ### Claim 15 An apparatus for adaptively setting a prefix length, the apparatus comprising: a memory configured to store and to manage a plurality of prefix lengths associated with base station types a receiver configured to receive base station information from a base station; a selector configured to select a prefix length from the plurality of prefix length based on the received base station information; and an inserter configured to insert a cyclic prefix having the determined prefix length in a guard interval of a transmission frame, wherein the plurality of prefix lengths are: previously determined by determining a comparatively short prefix length for a femtocell base station and mapping the comparatively short prefix length to the femtocell base station, and determining a comparatively long prefix length for a macrocell base station and mapping the comparatively long prefix length to a macrocell base station; and stored in the memory in as a prefix length set. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the selector is configured to: determine the base station type based on at least one of a base station identifier, a cell identifier, and a zone indicator, included in the received base station information; and find a prefix length mapped to the determined base station type from the plurality of prefix lengths stored in the memory.