date the authenticity and the integrity of binary data. To generate an l-bit CMAC tag u of message m using a B-bit block cipher E and secret key k, one first generates two B-bit sub-keys k1 and k2 using the following algorithm. This is equivalent to multiplication by X and x2 in a finite Galois field GF(2B). Let denote a logical left-shift operator, then [21]: 1. Calculate a temporary value ko = E k(0) 2. If MSB(ko) = 0 then k1 = ko << 1 else k1 = (ko << + a, where a is a constant that depends only on B. The constant a is the non-leading coefficients of the lexicographically first irreducible degree-B binary polynomial with the minimal number of ones. A polynomial is called irreducible, if it cannot be factored into nontrivial polynomials over the same field. For example, in the field of rational polynomials Q[x] (i.e., polynomials f(x) with rational coefficients), f(x) is called irreducible, if there do not exist two non-constant polynomials g(x) and h(x) in X with rational coefficients such that f(x) = g(x) h(x). 3. If MSB(k1) = 0 then 1 else k2=(k1 << 1) + a As an example, assume = 4, a = 0b0011, and ko = E k(0) 0b0101. Then k1 = 0b1010 and k2 0b0100 + 0b0011 = 0b0111. The CMAC tag generation procedure is as follows: 1. Divide message into B-bit blocks m = m1 Il Il Mn-1 mn where m1, are complete blocks 2. If mn' is a complete block then Mn = k1 + mn else + (mn'll 0b10...0) 3. Let = 0b00...0 4. For = n, calculate Ci = E k C - 1 mi) 5. Output u = MSB (cn) 6.4 Mobility management and handover Serving BS Target BS HO-REQ CID and TEK Pre-update HO-RSP Action Seamless HO Initiation Decline HO-IND (BS-ID) Unicast Encrypted DL Data, UL Grant BW-REQ, Unicast Encrypted UL Data RNG-REQ (CMAC) Target BS RNG-RSP (CMAC) Becomes Serving BS BW-REQ (0) Completion of Seamless HO FIGURE 6-13 Seamless handover call flow [1] base stations for the purpose of handover to a potential target BS. The cell reselection process does not need to occur in conjunction with any specific contemplated handover decision. 2. Handover Decision and