Channel estimation by phase multiplexed complementary sequences

A device for generating a composite signal e(n) having a form,

• e(n)=ejΦ·(s(n)+j·g(n)),
• where s(n) and g(n) represent first and second poly-phase complementary sequences transmitted with a phase shift separation of 90°, Φ represents an initial fixed and known phase shift, and j is the imaginary number,
• said device comprising:
• a first generator configured to generate the first sequence s(n), with n varying from 0 to N−1, where N represents a length of the first sequence s(n);
• an adder configured to produce said composite signal e(n);
• an output of the first generator connected to a first input of the adder;
• a second generator configured to generate the second sequence g(n), with n varying from 0 to N−1, where N represents a length of the second sequence g(n);
• a first circuit configured to phase shift 90° an output of the second generator;
• said output of the second generator connected to an input of the first circuit;
• an output of the first circuit connected to a second input of the adder;
• second circuit configured to phase shift by phase angle Φ an output of the adder;
• said output of the adder connected to deliver the composite signal e(n) into a transmission channel;
• and
• said composite signal e(n) delivered to the transmission channel providing an estimate of coefficients of the transmission channel by correlating respective received signals from the transmission channel associated with said complementary sequences s(n) and g(n) to estimate an attenuation and a phase shift of said composite signal.

An estimation device for receiving a received signal r(n) associated with a composite signal of complementary sequences s(n) and g(n), said complementary sequences s(n) and g(n) have the characteristics,

• Φs,s(n)+Φg,g(n)=k·δ(n),
• where one sequence Φs,s(n) represents an auto-correlation of s(n), one sequence Φg,g(n) represents an auto-correlation of g(n), δ(n) represents a dirac delta function, and k represents a scale factor,
• said device comprising:
• a processing circuit including a first correlator, a second correlator, and an estimation device;
• an input of the processing circuit receiving the signal r(n);
• said processing circuit configured to apply a real part of the signal r(n), rI(n), to the first correlator which proceeds simultaneously to a first correlation with the sequences s(n) and g(n);
• said processing circuit configured to apply an imaginary part of the signal r(n), rQ(n), to the second correlator which likewise proceeds to a second correlation with the two sequences s(n) and g(n);
• said first and second correlations providing an estimate for an attenuation and a phase shift of composite signal.