Time domain interference averaging with multiuser diversity in OFDMA systems
View Patent ↗Interference between multiple users operating under multiuser diversity within a coherence bandwidth in an OFDMA system is reduced by spreading out the users' transmission symbols randomly in time within the coherence bandwidth. When transmission symbols are randomly dispersed, the variance of interference between users in the same sub-band is reduced on average.
1. A method for data transmission in a wireless communication system comprising:
selecting a sub-band corresponding to a portion of a total bandwidth of the wireless communication system based on a quality of a channel used to communicate with a device, wherein the sub-band comprises a plurality of tones;
encoding data into codewords comprising symbols for transmission to the device; and
pseudo randomly distributing the symbols across the tones and across a burst transmission time,
wherein a number of symbols pseudo randomly distributed across the tones for a given time slot in the burst transmission time is less than a number of tones in the sub-band,
wherein the given time slot corresponds to an amount of time over which a tone is modulated by a single symbol.
2. An apparatus for data communication in a wireless communication system comprising:
an interleaving unit configured to interleave bits of a data stream;
a symbol mapper configured to assign groups of non-consecutive bits of the data stream, provided by the interleaving unit, to symbols; and
a scheduling unit configured to pseudo randomly distribute the symbols across tones of a sub-band, corresponding to a portion of a total bandwidth of the wireless communication system, and across a burst transmission time,
wherein a number of symbols pseudo randomly distributed across the tones for a given time slot in the burst transmission time is less than a number of tones in the sub-band,
wherein the given time slot corresponds to an amount of time over which a tone is modulated by a single symbol.
3. The apparatus of claim 2 , further comprising a coding unit configured to encode the bits of the data stream using one or more error coding schemes.
4. The apparatus of claim 2 , wherein the symbol mapper is configured to assign the groups of non-consecutive bits of the data stream to one or more complex symbols.
5. The apparatus of claim 2 , further comprising a bandwidth selection device coupled to the scheduling unit, the bandwidth selection device configured to select the sub-band based on a quality of a channel used to communicate with a device.
6. A method for data transmission in a wireless communication system comprising:
pseudo randomly distributing symbols across tones within a sub-band that is being used by a plurality of devices and across a burst transmission time such that a variance of interference between the plurality of devices is reduced;
wherein a number of symbols pseudo randomly distributed across the tones for a given time slot in the burst transmission time is less than a number of tones in the sub-band,
wherein the given time slot corresponds to an amount of time over which a tone is modulated by a single symbol.
7. The method of claim 6 , wherein the sub-band is used by the plurality of devices as a result of conflicts between multiuser diversity modes of two different base stations.
8. The method of claim 6 , wherein at least two of the plurality of devices are associated with different sectors of the wireless communication system.
9. The method of claim 6 , wherein the plurality of devices are mobile devices.
10. The method of claim 6 , wherein the plurality of devices are basestations.
11. The method of claim 1 , wherein the device is a mobile device.