tokens: ['of', 'reference', 'signals', 'for', 'the', 'case', 'of', 'a', 'UE', 'with', 'multiple', 'antennas', 'or', 'multiple', 'UEs', 'in', 'MUMIMO', 'is', 'to', 'be', 'studied', 'further', 'When', 'referencesignal', 'for', 'uplink', 'channelquality', 'estimation', 'is', 'transmitted', 'with', 'data', 'symbols', 'within', 'the', 'same', 'subframe', 'a', 'part', 'of', 'this', 'referencesignal', 'can', 'also', 'be', 'used', 'for', 'channel', 'estimation', 'for', 'demodulationdetection', 'of', 'the', 'data', 'symbols', 'The', 'two', 'SBs', 'can', 'be', 'used', 'for', 'transmission', 'of', 'referencesignals', 'for', 'different', 'purposes', 'listed', 'above', 'When', 'the', 'reference', 'signals', 'occupying', 'the', 'different', 'size', 'of', 'the', 'spectrum', 'FFS', 'are', 'multiplexed', 'into', 'overlapped', 'frequency', 'band', 'different', 'subcarriers', 'should', 'be', 'assigned', 'for', 'the', 'reference', 'signals', 'within', 'the', 'overlapping', 'frequency', 'band', 'in', 'order', 'to', 'achieve', 'orthogonal', 'transmission', 'The', 'uplink', 'reference', 'signals', 'are', 'based', 'on', 'CAZAC', 'sequences', 'Which', 'exact', 'type', 'of', 'CAZAC', 'sequences', 'is', 'FFS']