Communication structure with channels configured responsive to reception quality
A communication structure and method which allows connection-like and connectionless communications to be provided on a multiplexed link is provided. The structure and method can make efficient use of available transmission capacity and/or network resources while providing for both types of communication. Connection-like communications can be provided by a channel having allocated bandwidth dedicated to the communication while connectionless communication can be provided by a shared channel through which data can be transmitted to subscribers. In an embodiment, the shared channel transmits frames of packets addressed to one or more of the subscribers. The frames can have a robustly packaged header that can be received by all subscriber stations serviced by the base station while payload data in the frame can be packaged with a level of robustness appropriate for the intended subscriber station. Different packagings can include different encoding and/or modulation of the payload data. The allocation of bandwidth between the dedicated channels and the broadcast channel can be fixed, or can be managed to meet network or network operator requirements. The structure and method can also be managed by the network operator to permit prioritization of some communications over others. In another embodiment, two or more shared channels are provided. In another embodiment, dedicated channels can be created with different amounts of bandwidth and/or can employ modulation and/or encoding selected according to the reception-quality of the recipient station.
1 . A method of transmitting data from a network node to a plurality of subscriber stations over a multiple access link, comprising the steps of:
(i) determining the requirements for a first data transmission intended for a subscriber station;
(ii) selecting the use of a dedicated channel or a shared downlink channel to effect the first data transmission in accordance with the determined requirements, wherein the selected channel is selected from (1) at least a preselected minimum number of dedicated channels each allocated a portion of the transmission capacity of the link and (2) the shared downlink channel, the shared downlink channel allocated a portion of the transmission capacity of the link not allocated to the dedicated channels; and
(iii) if a dedicated channel is selected, obtaining a dedicated channel when available and transmitting the first data transmission thereon, and if a shared downlink channel is selected, transmitting the first data transmission on the shared downlink channel in the form of data packets addressed to the subscriber station, the data packets assembled into frames, at least some such frames including packets of data addressed to different ones of the subscriber stations.
2 . The method of claim 1 wherein the determination in step (i) is made in consideration of the QoS requirements of the first data transmission.
3 . The method of claim 1 wherein the determination in step (i) is made in consideration of the type of data to be transmitted.
4 . The method of claim 1 wherein, if a dedicated channel is selected and no such dedicated channel is available, the first data transmission is transmitted on the shared downlink channel.
5 . The method of claim 1 wherein step (ii), both a dedicated channel and a shared downlink channel are selected, an amount of the first data transmission corresponding to the transmission capacity of the dedicated channel being sent thereon and the balance of the first data transmission being sent on the shared downlink channel.
6 . A communications structure for communicating between a network node and a plurality of subscriber stations over a multiple access link, the structure comprising:
at least a preselected minimum number of dedicated channels, each dedicated channel having allocated to it a portion of the transmission capacity of the link to provide communication between the network node and a different one of the subscriber stations; and
at least one shared downlink channel having allocated to it a portion of the transmission capacity of the link not allocated to the dedicated channels and wherein each shared downlink channel is operable to transmit frames of packets from the network node to the subscriber stations, at least some such frames including packets of data addressed to different ones of the subscriber stations.
7 . The structure according to claim 6 wherein the portion of the transmission capacity of the link allocated to the at least one shared downlink channel is fixed.
8 . The structure according to claim 6 including at least two shared downlink channels, each shared downlink channel being operable to transmit frames of packets from the network node to the subscriber stations.
9 . The structure according to claim 8 wherein each of the shared downlink channels is operable to transmit the frames of packets to different ones of the subscriber stations.
10 . The structure of claim 8 wherein the potions of the transmission capacity allocated to each of the at least two shared downlink channels are unequal.
11 . The structure according to claim 6 wherein additional dedicated channels are created, as needed, by reallocating necessary transmission capacity of the link from at least one shared downlink channel to such additional dedicated channels.
12 . The structure according to claim 11 wherein the at least one shared downlink channel has a preselected minimum transmission capacity and reallocation of transmission capacity from the at least one shared downlink channel to the additional dedicated channels ceases before the transmission capacity allocated to the at least one shared downlink channel falls below the minimum transmission capacity.
13 . The structure according to claim 6 wherein data for a subscriber station is transmitted from the network node via a combination of a dedicated channel and the at least one shared downlink channel, the dedicated channel providing a first data transmission rate and the at least one shared downlink channel providing an additional transmission rate, as needed, to accommodate transmission bursts in excess of the first data transmission rate.
14 . The structure of claim 6 wherein at least one of the dedicated channels has a different amount of the transmission capacity allocated to it than does another of the dedicated channels.
15 . The structure of claim 6 wherein the link is a radio link.
16 . The structure of claim 15 wherein the radio link employs CDMA as a multiplexing technique.