Selecting an access point according to a measure of received signal quality

An apparatus for inclusion in a station of a wireless network, the apparatus comprising:

• a radio receiver to wirelessly receive data from at least one remote station, said data transmitted by the remote station as at least one packet of data, the receiver including an analog-to-digital converter producing samples of signals received at the station from the remote station, a packet of data including a part modulated in a pre-defined way and containing information indicative of the type of modulation used for at least some of the packet;
• a demodulator coupled to the radio receiver to demodulate samples of the signals received at the receiver from each station to produce demodulated signals from each of the remote stations;
• an error vector magnitude (EVM) calculator coupled to the receiver and to the demodulator, the EVM calculator operative to determine for each remote station from which data is received a measure of the received signal quality based on the samples of the received data from the remote station, the EVM calculator arranged to accept from the demodulator an indication of the type of modulation used for at least some of the packet, and
• a transmitter to transmit data for transmission,
• wherein a message to a particular remote station in response to the data received from the particular remote station includes a measure of the EVM of the data received from the particular remote station.

An apparatus for inclusion in a station of a wireless network, the apparatus comprising:

• a radio receiver to wirelessly receive data from at least one remote station, said data transmitted by the remote station as at least one packet of data, the receiver including an analog-to-digital converter producing samples of signals received at the station from the remote station, a packet of data including a part modulated in a pre-defined way and containing information indicative of the type of modulation used for at least some of the packet;
• a demodulator coupled to the radio receiver to demodulate samples of the signals received at the receiver from each station to produce demodulated signals from each of the remote stations;
• and
• an error vector magnitude (EVM) calculator coupled to the receiver and to the demodulator, the EVM calculator operative to determine for each remote station from which data is received a measure of a received signal quality based on the samples of the received data from the remote station, the EVM calculator arranged to accept from the demodulator an indication of the type of modulation used for at least some of the packet,
• such that, the receiving station selects one of the remote stations for communication according to a set of at least one criterion, said set including the respective received signal quality measure determined by the EVM calculator for data from each of the respective remote stations.

An apparatus for inclusion in a station of a wireless network, the apparatus comprising:

• a radio receiver to wirelessly receive data from a remote station, said data transmitted by the remote station as at least one packet of data, the receiver including an analog-to-digital converter producing samples of signals received at the station from the remote station, a packet of data including a part modulated in a pre-defined way and containing information indicative of the type of modulation used for at least some of the packet;
• a demodulator coupled to the receiver to demodulate samples of the signals received at the receiver to produce demodulated signals, the samples at decision points;
• a transmitter to transmit data for transmission to the remote station, the transmitter having a settable data rate, the data rate set according to a data rate signal accepted by the transmitter;
• and
• a data rate setting processor coupled to the demodulator and to the transmitter and producing the data rate signal for the transmitter, the data rate signal set such that in the case that a packet received at the station from a particular remote station includes an error vector magnitude (EVM) measure of a signal quality of a signal transmitted by the station and received at the particular remote station, the data rate for transmission to the particular remote station is dependent on the included EVM measure of the received signal quality,
• wherein in the case the packet received from the particular remote station includes the EVM measure, the particular remote station includes an EVM calculator coupled to a particular receiver at the particular remote station and to a particular demodulator at the particular remote station and operative to determine a received signal EVM measure based on the samples of data received at the particular remote station, the EVM calculator arranged to accept from the particular remote station's demodulator an indication of the type of modulation used for at least some of a packet received at the particular remote station.

A method in a station of a wireless network, the method comprising:

• wirelessly transmitting a request management message;
• wirelessly receiving data from at least one remote station, said data transmitted by the remote station as at least one packet of data, a packet of data including a part modulated in a pre-defined way and containing information indicative of the type of modulation used for at least some of the packet;
• sampling the received data corresponding to the received packet to form data samples;
• demodulating the data samples;
• ascertaining if the received data includes a response management message transmitted in response to a request management message;
• and
• if it is ascertained that the received data includes the response management message, ascertaining if a packet has been received from the particular remote station that transmitted the response management message indicating a measure of a signal quality of the data remotely received at the particular remote station corresponding to the transmitted request management message, wherein the measure of signal quality includes a measure of the error vector magnitude (EVM) determined at the particular remote station based on the samples of data received at the particular remote station and an indication of the type of modulation used for at least some of a packet received at the particular remote station,
• such that the message indicating the measure of signal quality can be used as an indication of the quality of communication achievable between the station and the particular remote station.

A method in a station of a wireless network, the method comprising:

• wirelessly receiving a signal from at least one remote station, said signal transmitted by the remote station as at least one packet of data, a packet of data including a part modulated in a pre-defined way and containing information indicative of the type of modulation used for at least some of the packet;
• demodulating samples of the received signals to produce demodulated signals from each of the remote stations, including ascertaining an indication of the type of modulation used for at least some of the packet, the ascertaining including demodulating the part containing information indicative of the type of modulation;
• calculating a measure of the received signal quality for the signals received from the remote station using samples of the received signal from the remote stations and respective indications of the types of modulation used in the respective received signals, the measure of received signal quality being a measure of the error vector magnitude (EVM);
• ascertaining whether the received data from any remote station is a request management message;
• and
• in the case it is ascertained that a request management message was received from a particular remote station, responding to the request management message by transmitting to the particular remote station a response management message that include a measure of the EVM of received data corresponding to the request management message,
• such that the particular remote station receiving the response management message receives an indication of a quality of the link between the station and the remote station without said receiving remote station necessarily being EVM-capable.

An apparatus for a station of a wireless network, the apparatus comprising:

• means for wirelessly receiving data from at least one remote station, said data transmitted by the remote station as at least one packet of data, a packet of data including a part modulated in a pre-defined way and containing information indicative of the type of modulation used for at least some of the packet;
• means for sampling the received data corresponding to the received packet to form data samples;
• means for demodulating the data samples including demodulating the part modulated in the pre-defined way;
• means for determining a measure of signal quality from the samples of the received data, the means for determining a measure of signal quality coupled to the means for sampling and to the means for demodulating;
• means for ascertaining whether or not at least some of the remote stations are access points, and
• means for selecting one of the access points for association in the case it is ascertained that at least some of the remote stations are access points, the selecting according to a set of least one criteria including the respective determined received signal quality measure for data from each of the access points,
• wherein the means for determining a measure of signal quality includes means for determining a measure of the error vector magnitude (EVM) using an indication of the type of modulation used for at least some of the packet.

An apparatus in a station of a wireless network, the apparatus comprising:

• means for wirelessly transmitting a request management message;
• means for wirelessly receiving data from at least one remote station, said data transmitted by the remote station as at least one packet of data, a packet of data including a part modulated in a pre-defined way and containing information indicative of the type of modulation used for at least some of the packet;
• means for sampling the received data corresponding to the received packet to form data samples;
• means for demodulating the data samples;
• means for ascertaining if the received data includes a response management message transmitted in response to a request management message;
• and
• means for determining if a packet has been received from the particular remote station that transmitted the response management message indicating a measure of a signal quality of the data remotely received at the particular remote station corresponding to the transmitted request management message, the determining carried out if it is ascertained that the received data includes the response management message, wherein the measure of signal quality includes a measure of the error vector magnitude (EVM) determined at the particular remote station based on the samples of data received at the particular remote station and an indication of the type of modulation used for at least some of a packet received at the particular remote station,
• such that the message indicating the measure of signal quality can be used as an indication of the quality of communication achievable between the station and the particular remote station.

An apparatus in a station of a wireless network, the apparatus comprising:

• means for wirelessly receiving a signal from at least one remote station, said signal transmitted by the remote station as at least one packet of data, a packet of data including a part modulated in a pre-defined way and containing information indicative of the type of modulation used for at least some of the packet;
• means for demodulating samples of the received signals to produce demodulated signals from each of the remote stations, including means for ascertaining an indication of the type of modulation used for at least some of the packet by demodulating the part containing information indicative of the type of modulation;
• means for calculating a measure of the received signal quality for the signals received from the remote station using samples of the received signal from the remote stations and respective indications of the types of modulation used in the respective received signals, the measure of received signal quality being a measure of the error vector magnitude (EVM);
• means for ascertaining whether the received data from any remote station is a request management message;
• means for transmitting;
• and
• means for responding to the request management message in the case it is ascertained that a request management message was received from a particular remote station, the means for responding couples to the means for transmitting and transmitting to the particular remote station a response management message that include a measure of the EVM of received data corresponding to the request management message,
• such that the particular remote station receiving the response management message receives an indication of the quality of the link between the station and the remote station without said receiving remote station necessarily being EVM-capable.

A method in a wireless station, the method comprising:

• wirelessly receiving a signal from a remote station corresponding to a packet transmitted by the remote station, a packet of data including a part modulated in a pre-defined way and containing information indicative of the type of modulation used for at least some of the packet;
• demodulating samples of the received signal to produce demodulated signals from the remote station, including demodulating the part modulated in the pre-defined way;
• determining at the station the measure of the received error vector magnitude (EVM) from samples of the received signal and from the information indicative of the type of modulation used for at least some of the packet;
• and
• selecting whether or not to associate with the remote station based on a measure of the EVM of data transported via the link between the station and the remote station.