 both contig- uous and non-contiguous carrier aggregation, the guard bands for a component carrier should be carefully set to suppress the intra-system and/or inter-system interference, while maintaining high spectral efficiency in data transmission. 11.4 MAC ASPECTS OF MULTI-CARRIER OPERATION The MAC layer in multi-carrier mode operates in the same manner as in a single-carrier mode. There is no difference between single-carrier and multi-carrier operation from a MAC addressing point of view. The security procedures between the MS and BS are performed over the mobile station's primary carrier. The security context created and maintained through this process is managed by the BS using the primary carrier. The network entry procedures in multi-carrier and single-carrier modes are the same, where the MS and BS indicate their support for multi-carrier mode during registration. The MS performs initial ranging and network entry only with a fully-configured carrier. Thus, a multi-carrier- enabled MS will have to obtain information about a base station's fully-configured carriers. During the initial network entry, the MS will inform the BS of its support for multi-carrier transmission through the AAI_REG-REQ message, and the BS will notify the MS whether it can support multi-carrier operation through an AAI_REG-RSP message. The basic multi-carrier capability exchange uses a 3- bit field in the AAI_REG-REQ/RSP message [2]. The basic multi-carrier mode includes informing the MS of the multi-carrier capability of the BS, including support for primary carrier change, as well as scanning of available carriers. The support for both carrier aggregation and switching does not imply E-MBS support, which is negotiated separately. The multi-carrier initialization procedure following network entry for a multi-carrier-enabled MS is shown in Figure 11-8. This procedure includes obtaining multi-carrier configuration for available carriers at the BS and information about assigned carriers consisting of the following two steps: (1) the 