A signalling method for use in a multiple-access communication system, the system comprising a first communication apparatus and a plurality of second communication apparatuses, the second communication apparatuses being operable to communicate with the first communication apparatus using respective parts of a shared communication frame and each using an available service level for such communication, the method comprising: assessing service-level requests from the second communication apparatuses to determine if there is a group of the second communication apparatuses that have similar or identical service-level requirements; the method characterised in that: if it is determined that such a group exists, employing a first control scheme specifying communication control information for the second communication apparatuses of the group to be transmitted in the shared communication frame; and for any second communication apparatus not part of the group, employing a further control scheme different from said first control scheme, the further control scheme specifying communication control information for that second communication apparatus, to be transmitted in the shared communication frame, wherein the communication control information of the first control scheme employs fewer communication control parameters than the communication control information of the further control scheme, such that use of the first control scheme for said group of second communication apparatuses enables communication for more such second communication apparatuses to be supported in said shared communication frame than if such a further control scheme were used for said group of second communication apparatuses. assessing service-level requests from the second communication apparatuses to determine if there is a group of the second communication apparatuses that have similar or identical service-level requirements; the method characterised in that: if it is determined that such a group exists, employing a first control scheme specifying communication control information for the second communication apparatuses of the group to be transmitted in the shared communication frame; and for any second communication apparatus not part of the group, employing a further control scheme different from said first control scheme, the further control scheme specifying communication control information for that second communication apparatus, to be transmitted in the shared communication frame, wherein the communication control information of the first control scheme employs fewer communication control parameters than the communication control information of the further control scheme, such that use of the first control scheme for said group of second communication apparatuses enables communication for more such second communication apparatuses to be supported in said shared communication frame than if such a further control scheme were used for said group of second communication apparatuses. if it is determined that such a group exists, employing a first control scheme specifying communication control information for the second communication apparatuses of the group to be transmitted in the shared communication frame; and for any second communication apparatus not part of the group, employing a further control scheme different from said first control scheme, the further control scheme specifying communication control information for that second communication apparatus, to be transmitted in the shared communication frame, wherein the communication control information of the first control scheme employs fewer communication control parameters than the communication control information of the further control scheme, such that use of the first control scheme for said group of second communication apparatuses enables communication for more such second communication apparatuses to be supported in said shared communication frame than if such a further control scheme were used for said group of second communication apparatuses.