Mobile devices, base stations, and/or relay stations may implement methods for decreasing required guard bands while also minimizing Adjacent Channel Leakage Ratio, when multiple mobile devices communicate over different respective adjacent specified frequency bands. For communications over at least one specified frequency band of the different respective adjacent frequency bands, a first bandwidth of uplink communications and/or a second bandwidth of downlink communications may be adjusted to differ from each other, and/or a communications bandwidth within the specified frequency band may be adjusted to be of a first size during a first portion of a specified data transmission period and to be of a second size during a second portion of the specified data transmission period, when at least some of the communications over the specified frequency band take place at frequencies adjacent to frequencies at which at least some of the communications take place over another specified frequency band.