1. A method performed at a user equipment comprising:
monitoring for a position reference signal broadcast by a network node;
measuring a time of arrival of a peak in a received signal indicative of receipt of said position reference signal and measuring a time of arrival of at least one further peak in said received signal;
transmitting a time offset signal indicative of a time difference between said arrival of said at least one fu1ther peak and said peak as pa1t of an enhanced reference time difference signal.
2. A method according to claim 1, wherein said step of measuring said time of
arrival comprises measuring a time of arrival of a plurality of fmther peaks; and
said step of transmitting said time offset comprises transmitting a time offset indicative of a time difference between said arrival of each of said further peaks and said peak.
3. A method according to claim 1, wherein said step of measuring said time of
arrival comprises measuring a time of arrival of a plurality of f1ther peaks; and
said step of transmitting said time offset comprises transmitting a time offset indicative of a time difference bet,veen said arrival of each of said peaks other than said frst received peak and an immediately preceding peak.
4. A method according to any preceding claim, wherein said peak comprises one of
a frst peak in said position refrence signal received by said user equipment and
a peak selected by said user equipment as a baseline peak.
5. A method according to claim 1, wherein said step of measuring said time of
arrival comprises measuring a time of arrival of a plurality of frther peaks; and
averaging a time of arrival of a frst and a fnal peak of said received position reference signal and transmitting said averaged time of arrival as said ofset signal.
6. A method according to any preceding claim, frther comprising monitoring fr
a frther position reference signal broadcast by a frther network node;
measuring a time of arrival of a peak in a received signal indicative of receipt of said frther position reference signal; wherein said frther network node comprises a reference network node, and said method frther comprises:

transmitting a time difference between said measured time of arrival of said peak of said position reference signal and said measured time of arrival of said peak of said further position reference signal as a reference signal time difference measurement.
7. A method according to any one of claims 1 to 5, further comprising monitoring
for a further position reference signal broadcast by a further network node;
measuring a time of arrival of a peak in a received signal indicative of receipt of said further position reference signal; wherein said network node comprises a reference network node, said method further comprising:
transmitting a time difference between said measured time of arrival of said peak of said further position reference signal and said measured time of arrival of said peak of said position reference signal as a reference signal time difference measurement.
8. A method according to any one of claims 1 to 5, further comprising monitoring
for a further position reference signal broadcast by a further network node;
measuring a time of arrival of a peak in a received signal indicative of receipt of said further position reference signal and measuring a time of arrival of at least one further peak in said received signal;
transmitting a time offset signal indicative of a time difference between said arrival of said at least one further peak and said peak as part of an enhanced reference time difference signal.
9. A method according to any preceding claim, further comprising an initial step of receiving a request signal indicating that an enhanced position reference signal time difference measurement should be performed.
10. A method according to any preceding claim, further comprising measuring an amplitude of said peak and said at least one further peak and transmitting a signal indicative of said amplitudes.
11. A user equipment comprising:
control circuitry for controlling said user equipment to monitor for a position reference signal broadcast by a network node;

measurement circuitry configured to detect and measure a time of arrival of a peak in a received signal and to detect and measure a time of arrival of at least one further peak in said received signal;
determining circuitry configured to determine a time difference between said arrival of said at least one further peak and said peak; and
transmitting circuitry configured to transmit a time offset signal indicative of said determined time difference as part of an enhanced reference time difference signal.
12. A method performed at a location server comprising:
receiving at least one enhanced reference time difference signal comprising:
a reference time difference signal indicating a difference in time of arrival between a peak in a position reference signal from one network node and a peak in a position reference signal from a reference network node; and
at least one time offset signal indicating a time difference between an arrival of a peak and a further peak in a position reference signal received at said user equipment from at least one of said network node and said reference network node; said method further comprising
analysing said time offset signal to estimate a time of arrival of said position reference signal at said user equipment travelling to said user equipment via a direct line of sight route; and
updating said reference time difference signal where said analysis indicates a direct, line of sight time of arrival of said position reference signal is different to said time of arrival of said peak.
13. A method according to claim 12, comprising an initial step of transmitting an enhanced reference signal time difference measurement to at least one user equipment.
14. A location server comprising:
a receiver operable to receive at least one enhanced reference time difference signal comprising:
a reference time difference signal indicating a difference in time of arrival between a peak in a position reference signal from one network node and a peak in a position reference signal from a reference network node; and
at least one time offset signal indicating a time difference between an arrival of a peak and a further peak in a position reference signal received at said user equipment

from at least one of said network node and said reference network node; said location server further comprising
an analyser operable to analyse said time offset signal to estimate a time of arrival of said position reference signal at said user equipment travelling to said user equipment via a direct route; and
correcting circuitry operable to update said reference time difference signal where said analysis indicates a direct route time of arrival of said position reference signal is different to said time of arrival of said peak.
15. A computer program which when executed by a processor is operable to control said processor to perform a method according to any one of claims 1 to 10 and 12,13.