A method by a base station for transmitting a plurality of system information bit streams, wherein each system information bit stream carries corresponding system information of one or more base stations in a wireless communication system, comprising: identifying a plurality of network-entry-related bit streams and a plurality of non-network-entry-related bit streams from the system information bit streams, wherein the network-entry-related bit streams carry essential system information for a terminal to access a network through at least one of the base stations, and wherein the network-entry-related bit streams are categorized into one group and the non-network-entry-related bit streams are categorized into an another group; modulating the network-entry-related bit streams according to a first set of modulation and coding schemes, MCSs, and modulating the non-network-entry-related bit streams according to a second set of MCSs, wherein each of the first set of MCSs and the second set of MCSs comprise one or more MCSs, respectively; and transmitting the system information bit streams with different predetermined periods, wherein the network-entry-related bit streams are periodically transmitted according to a first predetermined period, said method further comprising: periodically transmitting the non-network-entry-related bit streams according to a second predetermined period, wherein the second predetermined period is longer than the first predetermined period, obtaining a preferred broadcast period for each non-network-entry-related bit stream; identifying at least one low-rate bit stream from the non-network-entry-related bit streams according to the preferred broadcast period, wherein the preferred broadcast period of the low-rate bit stream exceeds one super-frame; and transmitting the low-rate bit stream in response to reception of a corresponding information request message from the terminal. identifying a plurality of network-entry-related bit streams and a plurality of non-network-entry-related bit streams from the system information bit streams, wherein the network-entry-related bit streams carry essential system information for a terminal to access a network through at least one of the base stations, and wherein the network-entry-related bit streams are categorized into one group and the non-network-entry-related bit streams are categorized into an another group; modulating the network-entry-related bit streams according to a first set of modulation and coding schemes, MCSs, and modulating the non-network-entry-related bit streams according to a second set of MCSs, wherein each of the first set of MCSs and the second set of MCSs comprise one or more MCSs, respectively; and transmitting the system information bit streams with different predetermined periods, wherein the network-entry-related bit streams are periodically transmitted according to a first predetermined period, said method further comprising: periodically transmitting the non-network-entry-related bit streams according to a second predetermined period, wherein the second predetermined period is longer than the first predetermined period, obtaining a preferred broadcast period for each non-network-entry-related bit stream; identifying at least one low-rate bit stream from the non-network-entry-related bit streams according to the preferred broadcast period, wherein the preferred broadcast period of the low-rate bit stream exceeds one super-frame; and transmitting the low-rate bit stream in response to reception of a corresponding information request message from the terminal. periodically transmitting the non-network-entry-related bit streams according to a second predetermined period, wherein the second predetermined period is longer than the first predetermined period, obtaining a preferred broadcast period for each non-network-entry-related bit stream; identifying at least one low-rate bit stream from the non-network-entry-related bit streams according to the preferred broadcast period, wherein the preferred broadcast period of the low-rate bit stream exceeds one super-frame; and transmitting the low-rate bit stream in response to reception of a corresponding information request message from the terminal.