A method for improving data transmission security at a first network node, comprising: sending, from the first network node to a user equipment, a preamble message after a user equipment is released by a second network node from a previous connection ; receiving, from the user equipment at the first network node, a connection request message including a token calculated based on a hash value and an integrity key , wherein the hash value represents data included in the connection request message; verifying, at the first network node, the token included in the connection request message by computing the hash value wherein verifying the token comprises: determining, at the first network node, that the hash value is computed before the data is ciphered; forwarding, to the second network node, the ciphered data for deciphering; receiving, from the second network node at the first network node, the deciphered data; and verifying, at the first network node, the token with the deciphered data; or verifying the token comprises: determining, at the first network node, that the hash value is computed after the data is ciphered; forwarding, to the second network node, the hash value for verifying the token; and receiving, from the second network node at the first network node, a verified token; and forwarding, from the first network node to a gateway, the data in response to verifying the token . sending, from the first network node to a user equipment, a preamble message after a user equipment is released by a second network node from a previous connection ; receiving, from the user equipment at the first network node, a connection request message including a token calculated based on a hash value and an integrity key , wherein the hash value represents data included in the connection request message; verifying, at the first network node, the token included in the connection request message by computing the hash value wherein verifying the token comprises: determining, at the first network node, that the hash value is computed before the data is ciphered; forwarding, to the second network node, the ciphered data for deciphering; receiving, from the second network node at the first network node, the deciphered data; and verifying, at the first network node, the token with the deciphered data; or verifying the token comprises: determining, at the first network node, that the hash value is computed after the data is ciphered; forwarding, to the second network node, the hash value for verifying the token; and receiving, from the second network node at the first network node, a verified token; and forwarding, from the first network node to a gateway, the data in response to verifying the token . determining, at the first network node, that the hash value is computed before the data is ciphered; forwarding, to the second network node, the ciphered data for deciphering; receiving, from the second network node at the first network node, the deciphered data; and verifying, at the first network node, the token with the deciphered data; or verifying the token comprises: determining, at the first network node, that the hash value is computed after the data is ciphered; forwarding, to the second network node, the hash value for verifying the token; and receiving, from the second network node at the first network node, a verified token; and forwarding, from the first network node to a gateway, the data in response to verifying the token . determining, at the first network node, that the hash value is computed after the data is ciphered; forwarding, to the second network node, the hash value for verifying the token; and receiving, from the second network node at the first network node, a verified token; and forwarding, from the first network node to a gateway, the data in response to verifying the token . <EOS>