Methods and systems for transmission of multiple modulated signals over wireless networks
View Patent ↗A method and apparatus for requesting and allocating bandwidth in a broadband wireless communication system. The inventive method and apparatus includes a combination of techniques that allow a plurality of CPEs to communicate their bandwidth request messages to respective base stations. One technique includes a “polling” method whereby a base station polls CPEs individually or in groups and allocates bandwidth specifically for the purpose of allowing the CPEs to respond with bandwidth requests. The polling of the CPEs by the base station may be in response to a CPE setting a “poll-me bit” or, alternatively, it may be periodic. Another technique comprises “piggybacking” bandwidth requests on bandwidth already allocated to a CPE. In accordance with this technique, currently active CPEs request bandwidth using previously unused portions of uplink bandwidth that is already allocated to the CPE. The CPE is responsible for distributing the allocated uplink bandwidth in a manner that accommodates the services provided by the CPE. By using a combination of bandwidth allocation techniques, the present invention advantageously makes use of the efficiency benefits associated with each technique.
1. A base station for a broadband wireless communication system, comprising:
a transmitter system for transmitting downlink (DL) traffic to a plurality of subscriber units and a receiver for receiving uplink (UL) traffic from the plurality of subscriber units; and
one or more processors having a media access control (MAC) module configured to
detect a bandwidth (BW) request in the UL traffic received from a subscriber unit,
identify in the BW request a requested amount of UL bandwidth pertaining to a specified connection established at the subscriber unit,
determine if bandwidth is available for the subscriber unit, and then allocate to the subscriber unit a granted amount of UL bandwidth,
maintain an UL map with uplink bandwidth allocations,
dynamically update the UL map to account for the granted amount of UL bandwidth,
provide the updated UL map to the transmitter system for transmitting to plurality of subscriber units, and
indicate to the subscriber unit that the request has been granted by providing the granted amount of UL bandwidth to the subscriber unit.
2. The base station as claimed in claim 1 , wherein the granted amount of UL bandwidth is equal to the requested amount of UL bandwidth.
3. The base station as claimed in claim 1 , wherein the granted amount of UL bandwidth is allocated from the base station to the subscriber unit based on a type of service established for the specified connection.
4. A base station for a broadband wireless communication system which transmits downlink (DL) traffic to subscriber units and receives uplink (UL) traffic from the subscriber units, the base station comprising:
an antenna system for transmitting downlink (DL) traffic to subscriber units and receiving uplink (UL) traffic from the subscriber units;
one or more processors having a media access control (MAC) module configured to
detect a bandwidth (BW) request in the UL traffic received from a subscriber unit,
identify in the BW request a requested amount of UL bandwidth pertaining to a specified connection established at the subscriber unit,
determine if bandwidth is available for the subscriber unit, and allocate to the subscriber unit a granted amount of UL bandwidth, if bandwidth is available for the subscriber unit,
maintain a DL map and an UL map with downlink and uplink bandwidth allocations respectively,
dynamically update the UL map to account for the granted amount of UL bandwidth, if the granted amount of UL bandwidth is granted, and
provide updated DL and UL maps to the antenna system for transmitting to the subscriber units.
5. The base station as claimed in claim 4 wherein the granted amount of UL bandwidth is equal to the requested amount of UL bandwidth.
6. A method of allocating bandwidth to subscriber units from a base station operating in a wireless communication system, comprising:
identifying an explicit message received from a subscriber unit requesting an allocation of uplink (UL) bandwidth in which to transmit a bandwidth request;
providing an allocation of UL bandwidth to the subscriber unit for enabling the subscriber unit to transmit the bandwidth request to the base station;
detecting the bandwidth request in the UL data received from the subscriber unit;
identifying in the bandwidth request a requested amount of UL bandwidth pertaining to one of a plurality of UL queues at the subscriber unit;
determining if the requested amount of bandwidth is available; and
allocating to the subscriber unit an UL bandwidth grant based on the requested amount of bandwidth and the bandwidth available for the UL data, the UL bandwidth grant being for distribution between one or more connections at the subscriber unit.
7. The method as claimed in claim 6 , further comprising:
encoding a unit of a pre-defined number of bits of data ready for downlink transmission using a Reed-Solomon encoding scheme,
modulating the unit according to a modulation format selected for DL communication with the subscriber unit; and
mapping each unit to DL data blocks of the DL sub-frame,
wherein the modulation format determines the number of data blocks and therefore the amount of time required to transmit each respective subscriber station.