We obtain the almost sure approximation of the partial sums of random variables with values in a separable Hilbert space and satisfying a strong mixing condition by a suitable Brownian motion. This is achieved by a modification of the proof of a similar result by Kuelbs and Philipp (1980) on $\phi$-mixing Banach space valued random variables. As by-products we get almost sure invariance principles for sums of absolutely regular sequences of random variables with values in a Banach space and necessary and sufficient conditions for the almost sure invariance principle for sums of independent, identically distributed random variables.
"Almost Sure Invariance Principles for Weakly Dependent Vector-Valued Random Variables." Ann. Probab. 10 (3) 689 - 701, August, 1982. https://doi.org/10.1214/aop/1176993777