Abstract:
A system and method to measure channel quality in terms of signal to interference plus noise ratio for the transmission of coded signals over fading channels in a communication system. A Viterbi decoder metric for the Maximum Likelihood path is used as a channel quality measure for coherent and non-coherent transmission schemes. This Euclidean distance metric is filtered in order to smooth out short term variations. The filtered or averaged metric is a reliable channel quality measure which remains consistent across different coded modulation schemes speeds. The filtered metric is mapped to the signal to interference plus noise ratio per symbol using a threshold based scheme. Use of this implicit signal to interference plus noise ratio estimate is used for the mobile assisted hand off in a cellular system, power control and data rate adaptation in the transmitter.
Abstract:
A method for allocating transmission resources in a base station (22a,22b) comprising determining a largest supportable packet size for a highest priority user based at least partially on a combination of available modulation types, a total number of codes available for packet transmission, a total amount of available transmission power available for packet transmission, and frame durations supported by a base station, wherein the determination comprises: - determining the total amount of transmission power available for packet transmission; - determining the total number of codes available for packet transmission, - determining a channel rate based on a minimal number of codes needed to transmit the supportable packet size; identifying the highest priority user from a plurality of users by determining an ideal channel rate for each of the plurality of users; the method comprising: - identifying a second highest priority user; - allocating transmission power and codes to the second highest priority user, wherein the transmission power allocated to the second highest priority user does not exceed the total transmission power minus the transmission power allocated to the highest priority user and wherein the number of codes allocated to the second highest priority user do not exceed the total number of codes minus the codes allocated to the highest priority user.
Abstract:
Efficient data communication in wireless communication system is provided by using centralized control of data communications, such as packet switched services, over the uplink channel (mobile station (MS) to base station (BS)). A multiple access protocol is used where packet data mobile stations make requests for uplink channel resources. The request messages transmitted by the MSs inform the BS of service parameters. Examples of such service parameters are available transmit power at the MS, the amount of data to transmit and Quality of Service (QoS). The BS then processes the received request messages and performs interference management calculations to determine the portion of the BS's receive power budget that can be allocated to the data user requesting service. These calculations are used to control the amount of interference seen at the base station, to assign a data rate to the user and to aid scheduling algorithms in computing service order priorities. Any scheduling algorithm may be used; for example, scheduling may be based on the amount of data to be transmitted, the age of the data or the service priority associated with the mobile station. The interference control is used to prevent the occurrence of catastrophic levels of interference while maximizing the utilization of resources on the uplink.
Abstract:
Data rate determination is provided in a system where the available power fraction and available Walsh codes in each active leg are dynamically changing over time. This method adapts the rate (modulation and coding) based on the combined resource (power & code space) levels seen at each cell. The method results in maximization of the rate supportable by each cell given their resource constrained situation while meeting the constraints of target packet or frame error rate and orthogonality. Furthermore, improved fast cell selection by the mobile results due to this approach that is based on knowledge of combined resource (power & code space) levels across the cells in the active set.
Abstract:
In a system and method to measure channel quality in terms of signal to noise ratio for the transmission of coded signals over fading channels, a Viterbi decoder metric for the Maximum Likelihood path is used as a channel quality measure. This Euclidean distance metric is filtered in order to smooth out short term variations. The filtered or averaged metric is a reliable channel quality measure which remains consistent across different coded modulation schemes and at different mobile speeds. The filtered metric is mapped to the signal to noise ratio per symbol using a threshold based scheme. Use of this implicit signal to noise ratio estimate is used for the mobile assisted handoff and data rate adaptation in the transmitter.