Binary parameters to OData calls from within SAPUI5

I am implementing a Function Import call from within a SAPUI5 project and am trying to send a compressed and encoded string (i.e. a binary file) as part of the parameters to this function import:

oDataModel.callFunction("/myFunctionImport", {

method: "POST",

urlParameters: {

SubmissionID: 1,

JSONzip: sBase64Data

},

success: function (oData, oResponse) {

// ...

},

error: function (oError) {

// ... }

});

where "sBase64Data" is the compressed and encoded JSON string. The gateway is correctly set up so that the parameter types to the Function Import as set as an Int32 and a binary file, respectively.

I keep getting a "Malformed URI literal syntax" error when I run this code. Any ideas of how I can directly send a binary call through to a function import?