Resource allocation to users in slotted code division multiple access systems using beams
The invention includes several embodiments for slot assignment in code division multiple access communication systems. Some of the embodiments relate to fixed beams and others relate to adaptive arrays. One embodiment for fixed beams assigns slots by first detecting a beam having the best received quality and selected the best slot from that beam. Another fixed beam embodiment determines the best slot or slots in a number of beams and determines the overall best beam/slot combination. Another fixed beam embodiment uses a modified interference factor. One embodiment for the uplink using adaptive arrays using a spatial analysis stage followed by a transmission power level estimation stage. An overall interference level associated with each slot is determined and a slot having the best overall quality is determined. Another embodiment for the downlink uses the spatial analysis and slot assignment of the uplink for the downlink. Another embodiment for the downlink uses a spatial and transmission power level estimation stages. For adaptive arrays, the slot assignment can be determined whether the pathloss for each user is estimated or not and whether signals from each user are received or not.
1. A method for assigning slotted code division multiple access time slots by a controller using a plurality of fixed beams, the method comprising for a given user:
measuring a quality of each fixed beam based on a received signal power of each fixed beam;
measuring a quality of each timeslot in each fixed beam based on an interference measurement of each timeslot;
calculating, by the controller, a modified interference measure for each timeslot by applying a weighting factor to a timeslot interference measurement and a beam received signal power and combining a weighted timeslot interference measure with a weighted beam received power measure;
ranking, by the controller, all modified interference measures; and
assigning, by the controller, a plurality of timeslots to the given user, wherein the plurality of timeslots are associated with the ranked best modified interference measures and at least one of the assigned timeslots is located in a different beam than at least one of the other assigned timeslots.
2. The method of claim 1 wherein ranking the modified interference measures uses a pathloss measurement for each slot.
3. A method for assigning slotted code division multiple access time using a plurality of fixed beams by a controller, the method comprising for a given user:
selecting at least one fixed beam;
measuring a quality of each selected fixed beam based on a received signal power of each fixed beam;
measuring a quality of each timeslot in each selected fixed beam based on an interference measurement of each timeslot;
calculating a modified interference measure for each timeslot by applying a weighting factor to a timeslot interference measurement and a beam received signal power and combining a weighted timeslot interference measure with a weighted beam received power measure;
ranking, by the controller, all of the modified interference measures; and
assigning, by the controller, a plurality of timeslots to the given user, wherein the plurality of timeslots are associated with the ranked best modified interference measures and at least one of the assigned timeslots is located in a different beam than at least one of the other assigned timeslots.
4. The method of claim 3 wherein a selected number of ranked fixed beams is two.
5. The method of claim 3 wherein a selected number of ranked fixed beams is a predetermined number.
6. The method of claim 3 wherein a selected number of ranked fixed beams includes all available fixed beams.
7. The method of claim 3 wherein a selected number of ranked fixed beams is a number of fixed beams exceeding a predetermined quality threshold.